The situation when you open a jar of varnish, and there is a viscous mass resembling honey or even jelly, is familiar to many craftsmen and home craftsmen. Drying of the solvent due to a loosely closed cover or storage in a warm place leads to an increase in the amount of viscosity material, which makes it impossible to apply it normally. However, you should not throw away expensive coatings, since in most cases its properties can be restored.
The main difficulty lies in the right choice. solventwhich corresponds to the chemical basis of the lacquer. The use of an inappropriate liquid can lead to coagulation - the fall of resin into the precipitation, after which the material will be permanently spoiled. In this article, we will discuss in detail what substances to use for different types of varnishes, how to properly conduct the dilution process and what you can not categorically do to save the varnish. adherence and the brilliance of the cover.
The restoration of the varnish is a delicate process, requiring accuracy and respect for proportions. Incorrectly selected chemistry can destroy polymer bonds, turning the glossy surface into a cloudy film with bubbles. Therefore, before you pour the first liquid you find, you need to accurately determine the type of your paint material.
Definition of the type of varnish and its bases
The first and most important step is to identify the chemical composition of the material. Lacquer is a solution of resins in organic solvents, and "like dissolves in like." If you make a mistake with the base, an irreversible chemical reaction will occur. Most often, they are on sale. alkyd, acrylic, nitrocellulosic and polyurethane compounds.
You can find out the type of varnish by marking on the label or can. Domestic manufacturers often use letter designations, which are the key to choosing a diluent. For example, an acronym PPF indicates a pentaphthal base (alkyd), AKA - on acrylic, NRC - for nitrocellulose. Imported materials are usually labeled in English, such as: Polyurethane or Acrylic.
If the label is lost or erased, a small experiment can be done. Apply a drop of the supposed solvent to the glass and add a little varnish to it. If the mixture becomes uniform and transparent, you guessed it. If the clouding, stratification or loss of flakes begins, the liquid is aggressive for this resin. Security In this case, the speed of work is more important.
⚠️ Warning: Never try to dilute water-based varnishes (acrylic emulsions) with organic solvents such as white spirit or acetone. This will cause the emulsion to fold instantly, and the material will turn into a rubber-like mass that cannot be used.
Solvents for varnishes on an organic basis
Organic varnishes, which include alkyd, oil and nitrocellulose, require the use of aggressive chemical reagents. For alkyd and oil compounds that are dried due to oxidation, the ideal choice is white-spirit. It is a distillation product that gently thins the resin without disturbing its structure.
For more rapid-drying nitrocellulosic varnishes (NRC) and some ether cellulosic materials require more potent ketone solvents. They're often used here. acetone or complex mixtures such as solvent 646, 647 or 650. These liquids have high volatility and dissolving ability, which allows you to quickly return the varnish working viscosity.
This means that the thickness of the film after drying will be less, and the shine may become less saturated. Therefore, do not exceed the recommended norms of diluent input, otherwise the coating will lose its value. wear-resistant.
- 💧 White Spirit is the best choice for alkyd varnishes (PF), oil compounds and bitumen coatings, providing a soft dilution.
- 🧪 Solvent 646 - a versatile mixture for nitrocellulose varnishes, epoxy resins and some acrylic materials, requires caution.
- 🔥 Acetone is a powerful solvent for cleaning tools and diluting very thick nitrolacs, but quickly evaporates.
- 🛢️ Solvent - an oil solvent suitable for diluting coal and some bitumen varnishes, has a specific smell.
Features of working with water (acrylic) varnishes
Water-based acrylic varnishes have gained popularity due to the lack of a sharp smell and environmental friendliness. However, their recovery raises the most questions. The main misconception is that they can be diluted with water from the tap. Water from the tap contains salts and chlorine, which can disrupt the chemical balance of the emulsion.
To dilute acrylic varnishes, only use distilled Or specially prepared soft water. Water should be added in very small portions, not exceeding 5-10% of the total volume, otherwise you can upset the balance of emulsifiers. After adding water, the varnish should be thoroughly mixed until a uniform consistency is obtained.
There are also special acrylics. thinnerwhich are sold in construction stores. They contain additives that prevent foaming and improve spreading. Using such professional products is preferable if you work with expensive parquet or furniture varnish, where surface quality is critical.
⚠️ Note: If the acrylic varnish is frozen, you can try to restore it, but only if it has not turned into a solid lump. After defrosting at room temperature, it must be thoroughly mixed with a mixer. If after stirring there are grains or flakes left - the material is hopelessly spoiled.
Table of compatibility of varnishes and solvents
So that you do not have to guess what kind of solvent is suitable for your case, we have prepared a summary table. It will help you quickly navigate the labels and pick up the right chemistry. Remember that there are no universal remedies, and experiments with mixing different bases almost always lead to spoilage of the material.
The table shows the main types of varnishes, their common markings and their corresponding solvents. Using data not listed in the table can lead to unpredictable results, such as clouding or prolonged drying.
| Type of lacquer | Marking (GOST) | Suitable solvent | Features of application |
|---|---|---|---|
| Alkyd | PF, GF | White Spirit, Solvent | Soft action, long drying |
| Nitrocellulosic | NRC | Solvent 646, 647, Acetone | High volatility, fire hazard |
| Acrylic (water) | AK, VD | Distilled water, special. thinner | Non-toxic, requires clean packaging |
| Polyurethane | UR | Solvent 646, Xylene, R-4 | It requires dryness, is afraid of moisture. |
| Bituminous | BT | Kalosha petrol, White Spirit | Strong smell, long drying |
Technology of diluting thickened varnish
The process of varnish restoration requires consistency and accuracy. Do not pour all the solvent into the jar at once. First, open the jar and assess the degree of thickening. If the varnish just became thicker but leaks, it needs a minimum amount of additives. If it turns into a gel, the process will take longer.
Pour a small amount of varnish into a separate clean container. Add the solvent gradually, at 3-5% of the volume, each time thoroughly stirring. Use a wooden or plastic stick so as not to scratch the container and not cause sparkling. Metal tools can be oxidized by some reagents.
☑️ Checking the polish readiness
After mixing, allow the composition to stand for 10-15 minutes. During this time, air bubbles will have time to come out of the liquid, and the solvent will be evenly distributed in volume. If a film or "skin" appeared on the surface, it must be carefully removed without mixing with the main mass, otherwise it will turn into small crumbs that will spoil the finishing coating.
Safety measures and waste management
Working with organic solvents carries health risks. The vapors of most of them are toxic and can cause dizziness, nausea, or an allergic reaction. Therefore, all work on diluting the varnish should be carried out in a good manner. airy indoors or outdoors. The use of a respirator and protective gloves is a requirement.
The fire hazard of materials is particularly dangerous. Solvent vapors are heavier than air and can roam around the floor, reaching the source of fire at a considerable distance. Smoking, using an open fire or a sparkling power tool within a few meters of the workplace is strictly prohibited.
Solvent residues and washing liquids cannot be poured into the sewer or onto the ground. This will cause serious damage to the environment. Collect waste in sealed containers and hand them over to special hazardous waste reception points or dispose of it according to local regulations. Careful attitude to nature is a sign of professionalism of the master.
⚠️ Warning: Keep open cans with solvents and diluted varnishes only upright, away from heaters and direct sunlight. The cover should be tightly closed immediately after use to prevent evaporation and the formation of explosive vapor concentrations.
Frequent errors in the restoration of paint materials
One of the most common mistakes is to try to dilute the varnish that has already begun to polymerize inside the can. If you see that the varnish is not just thickened, and began to turn into a rubber-like mass, no solvents will not help. The chemical reaction is irreversible and the material will have to be disposed of.
Another mistake is the use of dirty containers. Residues of water in a jar of oil varnish or traces of old dried lacquer will lead to marriage. Always use clean, dry dishes. Even one drop of water in a can of polyurethane varnish can spoil the entire volume due to foaming.
Can I mix the different manufacturers?
It is not recommended to mix varnishes from different manufacturers, even if they are of the same type. Different formulations may contain incompatible additives, plasticizers and siccativas. This can cause color change, decreased strength, or uneven drying of the coating. If mixing is necessary, make a small sample and check the result on the sample.
Don't forget. temperature. Dilution of cold varnish with a cold solvent can lead to precipitation. Materials must have room temperature (about 20°C) before starting work. This will ensure the correct interaction of the components and uniform viscosity.
FAQ: Answers to popular questions
Can I dilute the varnish with gasoline?
Regular motor gasoline can not be used, as it contains many additives, oils and dyes that will remain in the varnish after drying, making the surface sticky and yellow. You can use only special purified gasoline "Kalosha" (Galosha), which is designed to dissolve rubber and bitumen varnishes, but for alkyd and acrylic compounds it is not suitable.
How long can you store the diluted varnish?
The shelf life of diluted varnish is significantly reduced. If the factory packaging varnish can stand for years, then after opening and adding the solvent it is desirable to use it for 1-3 months. Acrylic varnishes on a water basis after dilution is better to spend within 2-3 weeks, as they can begin to develop bacteria.
What to do if lumps appear in the diluted lacquer?
If the lumps are small and there are few of them, you can try straining the varnish through a capron stocking or a special filter funnel (gazing will not work, it will absorb a lot of material). If there are many lumps or they are large and viscous, then the polymerization reaction has gone, and it is better to throw the varnish away so as not to spoil the product.
How to wash the tools after working with the varnish?
Tools (hands, rollers) should be washed immediately after work, without waiting for drying. For alkyd varnishes, use white spirit, for nitro - acetone or 646th solvent. The brushes are washed until the draining liquid becomes transparent, then dried and stored in a fluffy form.