Source: painting and varnishing. Wooden Boat Series.
Doug Templin
Abridged translation by S.B.
What are polyurethanes
Although polyurethane compounds have been around us for quite some time, they are still Hi-tech, because in all this time little has moved towards the development of more advanced paint systems.
Immediately after the introduction of the first two-component polyurethane paints, they gained a reputation for durability, chemical and wear resistance, and good color retention. They were immediately adopted by aviation, where corrosion protection is of paramount importance, aesthetics are important, and the cost of painting work is extremely high. Having established itself in aviation, polyurethane paints quickly moved into the field of "marine" paintwork materials for the same reasons. The automotive and industrial coatings industries are next in line, where the high cost of polyurethane paintwork justifies itself with increased resistance and durability. Today, there are an infinite number of applications for polyurethanes.
The chemical process for curing polyurethanes is relatively simple. It is a reaction of two compounds: one of them is called an isocyanate, the other is called a polyol, or high molecular weight alcohol. Isocyanate consists of chemical groups containing nitrogen, carbon and oxygen atoms, connected to each other in a special way, which makes them highly reactive. The isocyanate production process was developed by the German company Bayer (the one that is famous for the invention of aspirin), the production license was sold to Monsanto in the USA. Later, they bought shares and created Mobay Chemical, which still produces the purest, most advanced isocyanates in existence today.
Over the years, much has been improved: reducing the volatility of isocyanates, making them safer and improving performance. While the word "isocyanate" carries an ominous connotation, it has nothing to do with cyanide, a known poison. Isocyanate is a respiratory irritant, and its solvents have a toxic effect.
The component called "polyol" is usually a high alcohol molecular weight with the addition of pigments, fillers, and other components, which are collectively referred to as "pigmented base". The polyol has reactive hydroxyl groups (OH), exactly the same as those found in the water molecule H 2 O (H-OH). In alcohols that are used to form polyurethane, they have a very high activity, and their a large number of leads to the formation of numerous reaction pairs with isocyanate, and when the components are mixed, a very dense three-dimensional network structure is formed.
The number of existing polyols is as large as the number of existing varnish and paint companies, each developed for a specific purpose or to fill a highly specialized market niche. The goals of their development can be cost-effectiveness, resistance to temperature and chemicals, formation of a thick coating film, protection against corrosion. The alcohols we use in marine paints are designed for high initial gloss and long lasting durability.
Marine polyurethane coatings
Let's take a closer look at what polyurethanes are designed for use in a "marine" environment. A definite difference between them lies in the two types of polyols used - those that contain acrylic resin and those that have a polyester base. It is the resin that determines the internal structure and allows you to predict in advance what the coating film will be capable of and what it will not. Acrylic systems are generally referred to as modified polyurethanes, while polyester systems are considered "pure" polyurethane.
Paint systems based on acrylic resin are usually designed for minimum cure time, sufficiently hard surface and polishability. They are more vulnerable to temperature and chemicals, however, this does not prevent them from dominating the automotive industry and other Vehicle where polishability matters. Acrylic systems generally do not have the elasticity and abrasion resistance of their polyester counterparts.
Dupont's Imron system dominates among the acrylic-modified systems used for painting vehicles, and it is clear that it is also the leader among this type of "marine" systems. However, in highly corrosive environments and in southern latitudes, Imron does not appear to be as glossy and lightfast as high quality polyester systems. Since the latter tend to be more elastic, I think Imron is more suitable for metal and fiberglass boats than wood boats. Its use is also hampered by the fact that when painting with a brush, the result cannot be considered satisfactory.
Polyester systems are more commonly found in the jet industry, where solvent resistance and flexibility are a must. This market is dominated by products from Sterling (Sterling System), US Paint (Awlgrip), International (Interthane) and Koppers (Z-Spar). All these systems have a polyester base and are quite different from each other, although they can be considered approximately equivalent in terms of their final consumer qualities. Each of these firms has its own brand of paint that can be applied with a brush, which attracts them to Lately fairly broad attention.
Conditions for coloring
There are a great many stories about how this or that paint behaves - we all heard about successes and complete fiascos, moreover, when it came to the same brand of paint. It is natural that any of us want to achieve a good result when painting a boat, so you should know in advance some of important conditions that will help achieve this.
Dry wood. Polyurethane paints can only be applied to wood that is evenly dried and in a state of equilibrium moisture content with environment. On its surface there should be no areas of manifestation of an increased moisture content, giving themselves out as swelling and bubbling. If the enamel paint stays on the case for only one season, the probable cause may be precisely high humidity wood. With damp wood, you will not succeed with polyurethane paints.
A suitable candidate for polyurethane paint application is healthy wood, well dried and dimensionally stable, although in practice it is more likely to get good result with hardwood. Problems can arise with wood such as resin pine, in which numerous knots are constantly "tearing".
Rigid base. If the hull or deckhouse of your boat experiences significant shear deformations between the plating belts, polyurethane paints cannot be used there. How older age boats, the more weakened its fasteners and the greater the shift relative to each other, the sheathing boards are likely to experience. This can be caused by dynamic loads that occur when the boat moves through the water, or simply when the boat moves from a very hot climate to a very cold one, from a very wet to a dry one, and vice versa.
Any body that has seamed this in the past is guaranteed to behave in the same way with any paint, be it polyurethane or oil, thus reducing the expected life of the paint. When cracks begin to appear in the coating, it loses its integrity, begins to let water pass under it and no longer fulfills its function.
If the goal is to achieve maximum life from polyurethane paint, it should only be applied to a wooden boat that is not subject to bending deformations - this can be a well-sheathed hull in perfect condition, a boat with slatted sheathing and resin-glued seams, a hull with plywood, with a diagonal sheathing or pasted over with fiberglass.
Wedge-shaped skin grooves, left open and filled with putty, are the most likely place for shear deformations to develop even on the strongest hulls. Not all owners of this kind of grooves provide aesthetic satisfaction, but if they are there, then this is only for good. Unfortunately, these V-grooves hide the incipient microcracks in the coating, which are much less noticeable with them than on the body, in which adjacent boards are joined flush.
Connection density. wooden case must be carefully examined to ensure that all end and shoulder joints, grooves and cracks are tightly sealed and that water is prevented from entering the load-bearing elements hull structure, where it can penetrate along the gaps and along the fibers of the wood. Nothing breaks down a paintwork faster than soaking water, and often this process goes unnoticed by naive wooden boat owners, who end up with unsightly blisters of paint where water has penetrated below the surface. The polymer film resists this no more than ordinary oil enamel, in fact - it is even more vulnerable, because the moisture from the inside, trying to get to the surface, is not able to pass through the impermeable polymer film, as is the case with a less dense film of enamel coating. Therefore, moisture tends to tear off the film from the surface, forming a bubble in this place.
About security
Polyurethane and epoxy coatings, as a rule, contain more toxic components in their composition than conventional enamels. The latter should also be treated with some caution, because manufacturers are constantly working on improving them and modern enamels may contain primers, solvents and thinners that are just as toxic by inhalation or contact with the skin as those that we find in polyurethane paints. materials. Epoxy formulations, as everyone knows, contain many components that can cause skin allergies and other reactions. Contact with the skin should be avoided and only work in respiratory protection - at least a tight-fitting respirator with fresh activated carbon filters.
When applying polyurethane paints from a spray gun, the isocyanate component of polyurethane turns into an aerosol and can easily enter the human lungs. When painting with a brush, this process is not so pronounced, since the large molecular weight of the isocyanate does not allow its molecules to actively evaporate. Regardless of the chosen method of application, a person when working with polyurethane paints is exposed to the strong and toxic solvents contained in them, which easily evaporate and end up in the lungs. Need personal protective equipment.
When working on outdoors A respirator with a charcoal filter can provide the necessary protection. If you are the owner of a beard, you should understand that it will be difficult to achieve a snug fit of the mask and this kind of respirator will not provide you with adequate protection. When working in close contact with polyurethane, if you have a beard or if more reliable protection- wear a respirator overpressure and air supply from outside. You must wear a respirator and gloves while mixing, applying paint and cleaning from its chemical components. If at any time you smell paint in your respirator, the concentration of toxic substances in the air is dangerous and action is required. Remember to read the MSDS for all chemicals you use, and don't limit yourself to reading only what the label says.
Application of polyurethane paints
Polyurethane coatings are thin, durable and high gloss coatings that only look their best when applied to perfectly smooth surface(it doesn't matter if it's paint or varnish). Even the smallest hair-thin scratches will show through the film. Therefore, the preparation of the surface for painting is no less important than the painting process itself, which, in turn, proceeds differently for paint and for varnish.
If the boat's old enamel finish is undamaged and in good condition, it is an excellent base for polyurethane paint and only needs to be sanded to 180 grit, sanded to a high gloss, and primed with polyurethane primer before painting. The condition of the existing pavement should be assessed very critically. If the enamel is not in very good condition, you can achieve much better results by removing all existing paint to bare wood and starting from scratch.
There are two well-known surface preparation methods, both involving the application of epoxy over bare wood. The first way is to use any decent water-resistant, filler-free epoxy such as ChemTech, ColdCure, Detco, System3, Travaco, or West System (named in alphabetical order) to protect the wood and fill its texture. Two or three layers of it can be applied with a roller, then treated with coarse sandpaper and washed according to the manufacturer's recommendations. This will be the basis for the soils applied subsequently.
As alternative way a clean wood surface can be covered with several layers of epoxy primer, using a brush, roller or spray gun (if you have one and you have experience in using it). Soil layers are applied and ground one after another until all depressions and dips are filled flush with the surface. Epoxy resins applied in thick layers are very durable and difficult to sand, but it is this feature that makes it possible to harden the surface of the wood and reduce its susceptibility to impacts and scratches. Think carefully before using epoxy primers, which are easy to sand and have very low impact resistance. Should be remembered simple thing: what is easily sanded will be just as easily susceptible to dents, and the hardest surface will have the greatest strength.
When applying epoxy primers with a roller, a surface covered with a noticeable pimply texture is obtained, which is quite difficult to sand smoothly. In this situation, the spray gun in several passes would significantly save time. The soil will level itself out and required thickness recruited in a shorter period of time.
After the surface of the wood is reliably protected (and epoxy resins perform this function best), the next step should be to putty the surface. Putty for this can be prepared by yourself from epoxy, microspheres and aerosil, applying it with a spatula. You can also use factory-made low-density putties.
When the puttied areas have been sanded, sanded and there are no noticeable depressions, the entire sanded surface should be recoated with epoxy primer to close the pores of the microspheres destroyed during sanding. After priming with a roller, brush or spray gun and subsequent drying, the surface should be treated with sandpaper with a grain of 100-150.
Epoxy primers to improve the pouring on the surface contain solvents in their composition, which, as the composition cures, evaporate from the drying film. When solvents evaporate from the surface, the coating film shrinks, and this process continues until they are completely evaporated. Therefore, do not rush to grind a thick layer of epoxy primer (especially in cold weather), and even more so if several layers were applied and without waiting for the complete volatilization of solvents from the previous layer.
Epoxy putties containing fine fillers (such as Interlux Red Hand) can also be used to seal remaining wood pores and minor scratches. The surface after them is treated with a sandpaper with a grain of 150-180.
I do not recommend using it for repairing surface defects. wooden boat automotive polyester putty. polyester resin is a water-absorbing material, and these putties are very porous and contain a significant amount of solvent in their composition; when the ambient humidity changes, they tend to shrink and swell.
Even now it is still too early to start applying paint. It's time for the finishing ground. I prefer to use Sterling U-1000 polyurethane primer for this purpose, diluted to the desired consistency depending on the method of application (brush, roller or spray gun). It is a quick-drying polyurethane, it is sufficiently elastic, has excellent adhesion to all types of surfaces and is perfectly sanded. It should be applied in a smooth layer suitable for finishing sanding with grit 220.
After finishing sanding, the quality of the prepared surface is checked by rubbing it with the fingertips - the touch should not reveal tangible defects. The perfect finish needs the perfect base.
And now, finally, everything is ready. The pigmented paint base is mixed with a catalyst, usually a small amount of accelerator is added to them to speed up the film curing. The accelerator also avoids gloss haze, which can occur when working outdoors when an incompletely cured surface comes into contact with high humidity.
After mixing, allow the paint 30-45 minutes for the reaction to start and the formation of the polymer structure to begin. This will help the coating film behave in a more predictable manner once applied to the surface.
After this time, a thinner is added to the paint, the amount and grade of which depends on the climatic conditions and the method of applying the paint (brush or spray gun). It is necessary to dilute the paint, otherwise its poor bottling is guaranteed. Adding too much thinner will prevent the desired film thickness from being achieved and shorten the gloss life of the paint in the future.
To work, use a good brush - not necessarily the most expensive, but a combination of hog bristle and ox hair such as Corona, Redtree, Linzer, or more expensive Hamilton, if you want. Always keep a few of them in stock, because most likely one case will not do.
Brushes should be thoroughly cleaned immediately after use, then rinsed and cleaned with a scraper or wire brush to remove all traces of cured paint. The brush should be rinsed several times in solvent with wringing out after each time. As a rule, after two days of use, the brush is no longer suitable for applying a top coat due to the accumulation of cured paint near its holder. Set it aside - it may still be useful for applying primers.
Working on the painting of large areas such as the walls of the cabins and the sides, we came to the conclusion that perfect tool for applying polyurethane paint are foam rollers with a phenol coating (for solvent protection). One person using a roller rolls an area from edge to edge vertically and 30-45 cm horizontally, moderately dipping the roller and distributing the paint in a thin layer. His partner with a brush immediately follows and flutes the surface with two or three movements in the vertical and horizontal direction. Some argue that the last movement of the flute should be vertical, as this results in fewer sags and streaks. Others follow a more traditional technique, swiping the flute one last time in the direction of the board line. It seems to me that with the final vertical movement of the flute, smudges are still better eliminated. In the course of work, if the paint begins to seem inert to you, it may need to be further diluted, as in the case of brushing with ordinary enamel.
After the first pass of the entire surface and spraying of the tie coat, the coating should have a good gloss without cloudiness. Paint should be applied so much that when poured it gives a beautiful mirror surface. Many materials, when applied in a layer of this thickness at one time, quickly form streaks.
It is necessary to wait until the first layer of paint rises to the state of "tack free" (from half an hour to an hour), and then apply the second layer. It should also be of such thickness that a few minutes after application, the paint surface stretches and acquires a beautiful gloss. Two passes of the spray gun will usually achieve sufficient coating thickness.
Various decorative stripes can be applied to the painted surface once the paint has hardened enough to not be damaged by masking tape. This is usually possible as early as the next day after painting, although in colder climates it may take longer.
Cleaning of tools is easy with MEK solvent, do not forget about gloves and a respirator.
Application of polyurethane varnish
We have vast experience in applying polyurethane varnishes in all situations, and my advice reflects some important fundamentals gained through years of experimentation and failure.
As with paint, our goal is to achieve a continuous film on a hard, dry surface. However, in the varnish situation, the effect of solar radiation on the wood must also be taken into account. It is best to cover with polyurethane an already existing varnish coating of sufficient thickness. The amber-colored particles and UV inhibitors contained in the varnish protect the wood surface from damage. By itself, the varnish does not have sufficient hardness, its surface is easily scratched and quickly becomes cloudy under the influence of the sun. In contrast, polyurethane is hard, has a high gloss and is very scratch resistant. It will protect the varnish and unite beneficial features both coverage. This combination, according to our observations, extends the life of conventional varnish by at least 4-5 times, and we are talking about regions such as Florida, Southern California or the tropics.
After a film of ordinary varnish of the required thickness has been obtained on the surface of the wood, which makes it possible to hide surface defects (usually about eight layers), let the last layer dry and harden. Sand the surface with 220 grit sandpaper and coat it with two to three coats of clear polyurethane varnish, preferably within two to three days, one coat per day. Before applying the next layer, the surface is polished only to remove adhering dust particles and eliminate minor defects. The lacquer film does not have chemical resistance for at least 48 hours after application, so if the next coat of lacquer is applied in this time interval, it is not necessary to sand the entire surface. If more than two days have passed since the application of the polyurethane varnish, the surface should be carefully sanded until the gloss is completely eliminated.
In a similar way we have successfully covered teak, oak, spruce, pine, cedar with polyurethane varnish, pink tree, padauk, eucalyptus, ash and many other types of wood. Inside the hull, where there is no UV radiation, polyurethane varnish can be applied directly to the surface of the wood, which allows you to create an almost indestructible "armor" on the surface of wooden decks, lockers, galleys and many other places subject to intense wear.
Due to the fact that there is nothing easier than to clean the glossy surface of polyurethane, we have tried to coat it (with indispensable success) holds, engine compartments and polished brass parts. Polyurethane lacquer works well as a protective epoxy coating on hulls with laminated diagonal skin. Polyurethane reduces oxidative processes caused by solar radiation in epoxy resin and its chalking.
Care and repair
The surface painted with linear polyurethane is easy to care for - wash it from time to time with soap and water. Stubborn grease, oil, paint from the sides of other boats, buoys and moorings can be easily removed from the polyurethane surface with strong solvents without harming the polyurethane film.
Watch closely for any cracks or dents in the coating where water can enter and repair them immediately. Remember - in no case should water penetrate under the film.
After the end of the whole heartbreaking story with painting, the inevitable is still destined to happen. A collision with a buoy, the actions of a careless helmsman or the formation of a bubble lead to the fact that the brilliant appearance of the boat gradually ceases to be the center of everyone's attention.
A small scratch or chip can be repaired by mixing a small amount of a pigmented paint base with a catalyst. Let it stand for about an hour after mixing so that it acquires a thicker consistency. Then take a small brush and use it to fill in the defect. If necessary, repeat this procedure several times until the scratch is filled flush with the surface.
More significant scratches can be repaired by professional painters who own a spray gun. In this case, the place of repair will hardly differ visually. Repair of the damaged area is carried out (preferably) using epoxy putty, the surface surrounding the area is sealed for protection. The surface is primed with a very thin layer of the spray gun, sanded and painted. If you do not paint the entire open area up to the sealed border, you can avoid an unsightly transition. After a couple of days to dry the surface, dry particles of aerosol along the perimeter of the area are lightly sanded with 1500 grit (dry or wet), then polished with the finest polishing compound, and finally with Plexiglas polish. After that, the surface becomes almost perfect.
The owner can repair the damaged area with a brush on his own. In terms of its level, it will look approximately like a repair using ordinary enamel paint and will not be as subtle as the professional method described above. Best results I have been able to achieve this by working the perimeter of the freshly applied area with a dry brush, trying to smooth it flush with the previous one, as far as possible. When done correctly, these sorts of patches are barely noticeable from a few feet away.
Is there any benefit to this?
If the boat was in good condition, and the preparation, painting itself and subsequent care were carried out correctly, the polyurethane coating can last you 3-5 years. During this time, the painted surface will be easier to clean and more resistant to scratches and abrasion than conventional enamel. Dirt, oil and fuel will stick to it much less, and the color will remain brighter and more vibrant. Losses in the form of twice the cost of painting are turned into gains in the third year, even if only the cost of materials is taken into account.
We all know how laborious the process of lifting and painting a boat can be, so after two years the polyurethane paint system begins to pay for itself. The difference in labor costs when priming and painting with polyurethane over a strong existing coating is quite small compared to conventional enamel. If you start everything from scratch, i.e. from bare wood - the cost of painting will undoubtedly be more expensive. However, given that over the next ten years the boat will only have to be repainted once or twice, it is easy to calculate the savings. Therefore, do not get depressed from calculating the cost of the materials needed for this, take into account the potential of polyurethane.
The union of wood with polyurethane may be the best combination. The result of the work is absolutely magnificent and far exceeds the traditional "yacht" enamels in terms of durability. This is my opinion about packing wood in "plastic".
Number of impressions: 6132
Parquet chemicals are a group of products used to protect and decorate wooden floor, wall and ceiling coverings. This includes varnishes and paints, primers and putties, stains and toning, adhesives, antiseptics, solvents and thinners. Most store-bought wood varnishes are usually a liquid, ready-to-apply mixture. The question arises: is it possible, and how to dilute the varnish if it is too viscous?
When diluting varnish, it is important to observe the correct proportions. To answer this question, several factors must be taken into account. First, we pay attention to the main composition of the mixture. Secondly, we select the right solvent. Thirdly, when mixing, we observe proportions so as not to lower the quality of the material. Let us consider in more detail how thickened varnish can be diluted and how to do it right? And also, what to use to remove the old protective coating from wood and what is the care of the tool?
Dilute, dilute or dissolve
At first glance, there is no difference. With the help of a special tool, we bring the lacquer substance into a “working state”. A solvent is a liquid that dissolves dried varnish, bringing it from a solid to a liquid state. We use a thinner if it is required to change (reduce) the viscosity of paints.
Some types of organic eluents perform both roles, but some may be effective in one task and completely useless in another. So, for example, compositions of polyurethane, alkyd and oil groups can be diluted with white spirit. But if the varnish has dried up, it will not work to dissolve it with white spirit.
White spirit can be used to thin some varnishes. But shellacs, on the contrary, equally dissolve and dilute with denatured alcohol. But let's not go into such subtle details.
If you need advice on how to thin varnish or what to use to thin paints, it is best to consult with experts in this field.
We propose to consider in detail which solvents are required to be used in specific cases.
Polyurethane blends
Polyurethane varnishes, paints, primers, adhesives, etc. contain polyurethane, a modern polymer. The combination of its properties surpasses such well-known materials as rubber, plastic, rubber, metal. For obtaining paint and varnish and adhesive solutions of high strength, in industrial production it (polyurethane) is mixed with special chemicals.
A lot of polyurethane varnishes are produced and water-based. This parquet chemistry is environmentally friendly and non-toxic.
If necessary, make the substance more liquid, as a diluent for polyurethane compounds, you can use:
- toluene;
- xylene;
- acetone;
- eluents like R-4, R-5.
Acetone - good remedy for thinning polyurethane varnishes Alkyd mixtures
Alkyd compounds have good adhesion, moisture resistance, insensitivity to ultraviolet radiation, strength. They can be used for outdoor and internal works. In alkyd mixtures there is a main component, organic solvents, driers (for faster drying), additives. The main component may be:
- pentaphthalic resin;
- glyphthalic resin with cottonseed oil;
- mixture of melamine-formaldehyde and alkyd resins.
To enhance the properties of materials, elements of alkyd resins are often included in the composition of multicomponent varnishes, paints, and enamels. The traditional thinner here is white spirit.
Bituminous mixtures
Bituminous varnish is a mixture of special grade bitumen, various resins and oils. After drying, a durable black film is formed on the surface, moisture resistant, immune to chemical attack. It is considered a fairly new material in domestic use. Belongs to the category of inexpensive. It is often used as an anti-corrosion protective layer.
For wooden surfaces, it is used when it is not necessary to emphasize the natural texture of the base (instead of paints). Bituminous material has found application as decorative coating for the effect of aging surfaces (patina). Another unique feature of bituminous mixtures is cold gluing. The bituminous solution is diluted with white spirit.
So that it does not thicken during storage, the container must be airtight. The storage place should be dark (without direct sunlight), with moderate temperature and humidity.
Bituminous varnish protects the surface very well from moisture and chemical influences, diluted with white spirit Yacht varnishes
It is one of the most effective means of protecting natural wood surfaces. Already from the name, the features of the sphere where it is used are clear. At the same time, the yacht composition is excellent for woodworking inside and outside of any objects (not only boats, boats, yachts). It is immune to moisture, temperatures, aggressive environments.
Yacht varnish. Basic properties:
- high degree of protection of wooden structures;
- physical and mechanical immunity to the influence of external environments;
- durability, extending the life of wood.
To achieve such results, toxic chemical elements (toluene, xylene) are used in the production of the material. There are several production technologies:
- alkyd yacht (based on organic solvent white spirit);
- urethane-alkyd yacht (eluent is the same, but in smaller quantities);
- alkyd-urethane yacht (solvent additives are highly volatile);
- acrylates (water-based compounds).
Dilutes yacht varnish with white spirit, no more than 5% of the total volume. The solvent acts on the substance only when it is fresh. After drying, the lacquered parquet coating will become resistant.
Varnish for yachts, boats, boats has high wear resistance and is also diluted with white spirit How to remove dry polish
The above are mainly ways to improve the consistency if the varnish has thickened. And what should be done to remove varnishes and paints from painting tools? Can the synthetic material be removed from the wood after application?
Old furniture or wood just won't work. Usually, where possible, scraping or grinding is used. For non-mechanical removal, the type of solvent is selected individually. The main composition is taken into account and Chemical properties varnishing.
The easiest way to remove an already unusable parquet protective coating is to use a special remover. The substance is a chemical mixture. You can use liquid, gel or powder. Acetone copes with the simplest types of paints and varnishes. To remove shellac, denatured alcohol is more suitable.
First, a liquid, gel or powder is applied to the varnish surface. Then you need to wait for the softening of the film. To speed up the process, it is recommended to cover the treated surface with polyethylene. After some time (from 40 minutes to 4 hours), the old varnish will begin to swell, darken. What to do next?
To remove softened varnish, it is more convenient to use a spatula. You need to work carefully so as not to damage wooden surface. What to do if the first time is old protective covering not removed completely? If necessary, processing can be repeated.
To remove residues of the substance from the painting tools are used:
- Water-based parquet varnish is washed off freshly with a warm water-soap solution;
- White spirit, kerosene, turpentine are suitable for most paints and varnishes based on organic solvents. The remains of the substances are well rinsed out, then the instrument is washed with some kind of agent. household chemicals and rinse well with water.
When choosing the type of eluent for diluting paint and varnish mixtures, it is important to carefully study the composition, as well as use the manufacturer's recommendations indicated on the package.
Do not forget about personal protective equipment, especially if you have to work with strong-smelling, quick-drying compounds. Ventilation of the room during and after work will protect against poisoning by toxic fumes. Keep these materials away from children.
The areas of application for solvents and thinners are extensive. By doing repair work we inevitably deal with solvents for varnish, enamel, paints. In construction, solvents for rust, concrete, liquid glass, liquid nails, polyurethane foam and other materials. Solvents are constantly used by artists, and in everyday life they help us remove difficult pollution. Our article will help you understand this big topic so that you can quickly answer the question: which solvent is better to use in each case.
Solvent vs Thinner: What's the Difference?
The terms "solvent" and "diluent" are often used interchangeably. However, there is an important difference between them. If to speak plain language, the solvent interacts directly with the film-forming (curing) component.
For example, gasoline is a popular solvent for oil paints. It dissolves the binder, so it can dilute the paint for application and at the same time can remove dried paint stains.
The thinner does not dissolve the substances that form the film, but can only reduce the viscosity of the composition. For example, water dilutes water-based paint well, but it will not be able to wash off the dried one.
Solvent types
For convenience, we divide all solvents into the following groups:
- Solvents for paints and varnishes(paints, enamels, varnishes), as well as adhesives and primers
- Solvents building materials (solvents for bitumen, concrete, foam, rubber, rust, etc.)
- Household solvents(stains from oil, grease, adhesive tape, etc.)
- Artistic solvents
Solvents for paints and varnishes
Almost all solvents for varnishes, paints and enamels are volatile organic substances with a low boiling point. These properties ensure rapid drying of the compositions after application.
Solvents are:
- homogeneous - based on one substance or a mixture of homogeneous substances (for example, toluene);
- combined - based on several homogeneous solvents in a certain proportion (for example, P-4 = toluene + acetone + butyl acetate).
As a rule, combined ones are distinguished by higher efficiency and targeted action.
With the help of our table, you can easily understand which solvents are used for which paints.
Purpose of solvents
|
Solvent |
Type of paintwork |
|
Homogeneous solvents |
|
|
Solvent (more precisely thinner) of acrylic paint, water-based paint and other water-dispersion paints and nibbles |
|
|
Solvent for oils and bituminous paints, varnishes, enamels |
|
|
Turpentine |
Thinner for oil and alkyd-styrene paints |
|
White Spirit |
Solvent for oils and alkyd paints and enamels (including PF-115, PF-133, PF-266), bituminous mastics, varnish GF-166, primer GF-021 |
|
Solvent (petroleum) |
Solvent for glyptal and bituminous varnishes and paints (including melamine alkyd). |
|
Xylene (petroleum) |
Solvent for glyptal and bituminous varnishes and paints, epoxy resin. |
|
Perchlorvinyl paint thinner |
|
|
Combined (numbered) solvents |
|
|
Solvent 645 |
Nitrocellulose solvent |
|
Solvent 646 |
Universal solvent for nitro paints, nitro enamels, nitro varnishes general purpose, also epoxy, acrylic, solvent |
|
Solvent 647 |
Solvent for nitro-enamels, nitro-varnishes for cars |
|
Solvent 649 |
Solvent NTs-132k; GF-570Rk |
|
Solvent 650 |
Auto enamel solvent NTs-11; GF-570Rk |
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Solvent 651 |
Oil solvent |
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Solvent P-4 |
Polyacrylate, perchlorovinyl, coatings with copolymers of vinyl chloride with vinylidene chloride or vinyl acetate |
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Solvent R-5 |
Perchlorovinyl, polyacrylate, epoxy |
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Solvent R-6 |
Melamine-formaldehyde, rubber, polyvinyl-butyral |
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Solvent R-7 |
Thinning varnish VL-51 |
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Solvent R-11 |
Perchlorovinyl, polyacrylate |
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Solvent R-14 |
Epoxy enamels cured with isocenate hardeners |
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Solvent R-24 |
Perchlorovinyl |
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Solvent P-40 |
Epoxy |
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Solvent R-60 |
Cresol-formaldehyde, polyvinyl butyral |
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Solvent R-83 |
Epoxyester |
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Solvent R-189 |
Solvent for polyurethane varnish |
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Solvent R-219 |
Polyester resin solvent |
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Solvent R-1176 |
Solvent for polyurethane paints and enamels |
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Solvent RL-176 |
polyacrylate, polyurethane |
|
Solvent RL-277 |
Polyurethane |
Other useful properties of these solvents:
— cleaning and degreasing the surface;
— removal of coatings from brushes, rollers, spatulas and other tools.
Video on how to rinse the spray gun with a solvent
Paint strippers: fresh and old
If, during the performance of work, paint stains turned out to be in the wrong place (furniture, floor, glass were stained), it can be removed with the solvents indicated in the table. True, for delicate surfaces (wood, laminate, plexiglass), you should not use combined compositions such as R-646. It is better to use homogeneous ones and be sure to first check their effect on an inconspicuous area.
Special solvents are available for removing old paints from large areas. They will help remove paint from the walls, with metal products and so on.
Building materials solvents
Removal of hardened mortars often causes serious difficulties. Manufacturers have done everything to make bitumen, concrete, mounting foam, etc. as resistant to chemical attack as possible. What solvents will help in this case.
Solvent for concrete, cement, grout- a mixture of concentrated acid, protective substances for metals and inhibitors.
Liquid glass solvent - washable from tools warm water immediately after application. Hardened can be removed with organic solvents
Solvent for polyurethane foam - fresh foam is easily removed with ethyl acetate or solvents based on it (for example, P-645, 647). The solvent of the hardened polyurethane foam can be considered folk remedy"Dimexide" (sold in pharmacies). Also "Dimexide" is excellent superglue solvent.
Liquid Nail Solvent- those that have not hardened are removed with mineral-based solvents or water. Hardened can be removed mechanically or by heating with a hair dryer to a temperature above 50 ° C
Rust remover- special formulations based on phosphoric acid, tannin, hydroxycarboxylic polybasic acids.
Silicone thinner ( silicone sealant, glue)- along with special formulations from manufacturers of sealant and glue, you can use acetic acid or white spirit.
Polymer solvents:
— PVC- tetrahydrofuran, cyclohexanone for several days;
— polyethylene- xylene, benzene when heated;
— polyurethane foam- it is removed only with fresh special solvents from producers.
Rubber and rubber solvent - toluene and other organic solvents are suitable to remove the substance (rubber dissolves, rubber swells and collapses)
Solvent bituminous mastic - toluene, solvent, gasoline, white spirit
Styrofoam solvent - acetone, solvent R-650
Solvent for paraffin and wax- kerosene, white spirit, gasoline, acetone.
In the next article, we will tell you about small-scale solvents and solvents used by artists.
Polyurethane paints and varnishes are widely used in the furniture industry, and in building supermarkets you can easily find these paints and varnishes for domestic use. Therefore, we believe that it makes sense to get acquainted in detail with the properties of polyurethane paints and varnishes.
Polyurethane paints and varnishes (paints, varnishes, primers) are a large group of polymers:
- The main component of polyurethane resins are polyols synthesized on the basis of substances traditionally used for alkyd coatings, so the price of polyurethane materials is relatively low. Polyols are oligomers consisting of fairly large molecules with about several tens of active sites.
- The second component of polyurethanes are hardeners based on diisocyanates, consisting of small molecules with two active sites. During film formation, the active sites of diisocyanates bind to the active sites of polyols, and a urethane bond is formed.
- One polyol molecule can be linked by diisocyanates to many other polyol molecules, and so on. Thus, films of polyurethane coatings are obtained, having a branched three-dimensional mesh structure. Such films are resistant to water, acids, mineral and organic oils, gasoline, oxidizing agents.
The vapor permeability of polyurethane paints, varnishes, primers is an order of magnitude lower than that of nitrocellulose.
Polyurethane paints, varnishes, primers are mainly used for finishing wooden products indoors.
The ratio of components in polyurethane paints and varnishes
The components of the working mixture of polyurethane paints and varnishes are usually mixed with two parts of resins plus one part of hardener immediately before use, since the life of polyurethane materials is short: 3-6 hours.
The ratio of the base and the hardener in the working mixture is obtained in such a way that the number of bonds between the molecules is equal to 60-90% of the maximum possible.
Deviations of the amount of hardener in the working mixture from the specified proportion within ± 10% do not lead to a significant change in the properties of the coating.
Solvents for polyurethane varnishes and paints
Solvents of polyurethane materials are mixtures of liquids with a low boiling point, alcohol and water impurities in them are unacceptable.
For polyurethane materials, a system of tinting pastes has been developed, which can be added to varnishes in a significant amount - up to 30% without deterioration operational properties materials.
Using a variety of polyurethane materials, almost any given type of finish can be obtained: from simple single-layer to exclusive.
In domestic technical literature decorative properties polyurethane coatings are usually distinguished by the term "silkyness".
Dried polyurethane coatings are devoid of any toxicity, allow food contact with them, polyurethane materials are produced certified according to the strict European standard related to the safety of toys.
