A sharp thickening of nitrocellulose or acrylic enamel in the midst of work often indicates the need to urgently find what to replace the finished diluent P-4, since the use of improper chemistry threatens irreversible defect of the coating and damage to the tool.
It is important to note right away that P-4 is a mixture of ketones, esters and aromatic hydrocarbons. It is this balance that ensures the correct evaporation and formation of the film. If you choose to use an inappropriate substitute, the paint may curl up, cloud or dry with defects like shaverine. Therefore, before pouring something into a jar of enamel, it is necessary to carefully study the properties of the available liquids.
In this article, we will discuss in detail what solvents can become a full-fledged replacement, in what proportions they can be mixed and what can not be done categorically. You will learn about the nuances of working with acetone, solvent popular solvent 646Get practical tips on the safe use of volatile substances in garage conditions.
Chemical composition and features of the diluent P-4
For the correct selection of analogues, you need to understand what the original product consists of. P-4 diluent It is a colorless or slightly yellowish liquid with a sharp characteristic odor. Its formulation is strictly regulated by GOST and includes three main components: acetone, butyl acetate and toluene (or other aromatic hydrocarbons). Each element performs its function: acetone provides a rapid start to dissolution, butyl acetate regulates the rate of drying, and toluene improves fluidity.
The main purpose of R-4 is dilution of nitrocellulose varnishes and enamels (NC), as well as perchlorovinyl materials. Technical specifications This solvent is selected so that the paint after application lies flat and does not form a whitish coating. Disruption of the balance of components leads to the fact that the solvent evaporates too quickly or, conversely, dries too long, which affects adhesion.
⚠️ Caution: Using pure acetone instead of P-4 in large quantities can cause the paint to boil on the surface and form craters. Acetone evaporates too quickly and cools the surface strongly, condensing moisture from the air.
When looking for a replacement, it is important to consider the volatility of the mixture. If you work in a hot room, you need a less volatile composition to paint has time to spread. In cold shop, on the contrary, more active components are required to prevent leakage. Understanding these processes will allow you to competently mix available fluids.
When mixing different solvents, always test for compatibility with a small amount of paint in a separate container before diluting the bulk.
Solvent 646 and 647: the main competitors
The most common and affordable replacement for P-4 is solvent 646. It is a versatile composition that also contains acetone, toluene, butyl acetate, ethylcellosolv and other alcohols. The 646 is even richer in composition than the R-4, making it more aggressive. It does a great job with nitro-enamels, but requires caution when working with some types of plastic and old coatings.
Solvent 647 It is also often seen as an alternative. Its formula is similar to 646, but the proportions of the components are changed, making it slightly less active against some resins. It is excellent for diluting nitrocellulosic materials, but it can act slower than P-4 or 646 when cleaning the tool.
The main advantage of these analogues is their availability. They are sold in any construction store and often cost less than specialized brands. However, if you work with expensive car enamels, it is better to pre-check the reaction of the material. Aggressive alcohols in 646 can change the shade of some pigments.
- ✅ Solvent 646: powerful dissolution force, ideal for nitro-emals, but can be aggressive to plastic.
- ✅ Solvent 647: slightly softer than 646, well suited for diluting varnishes and enamels on nitrobase.
- ✅ Availability: They are sold everywhere, making them the best replacement for an urgent need.
When using 646 instead of P-4, it is recommended to add it portioned, constantly monitoring the viscosity of the paint. Due to its high activity, it can make the material too liquid if overdosed with dosage.
Acetone and esters: when you can and when you can not
Clean. acetone It is one of the main components of P-4, which is a significant part of its volume. The question is, can it be used as a self-contained solvent? The answer is: it is possible, but with limitations. Acetone perfectly degreases and dissolves many resins, but its ultra-high volatility creates problems when painting large areas.
If you wash the spray or brushes, pure acetone will be perfect. It will quickly evaporate and leave no greasy marks. However, when diluting paint for application to the body, it can lead to matteness and “orange peel”. In this case, acetone is better used in a mixture with less volatile substances, for example, with butylacetate Or toluene, if possible.
⚠️ Note: Acetone is able to dissolve certain types of plastics and rubber. Be extremely careful washing the parts of the spray gun with rubber seals - they can swell and lose their tightness.
Esters such as butylacetate are a milder alternative. They evaporate more slowly, which allows the paint to spread better. A 1:1 mixture of acetone and butyl acetate will produce a result very close to the original P-4. This is an excellent option for those who want to prepare a solvent of the desired viscosity on their own.
It is important to remember the hygroscopicity of acetone. It actively absorbs moisture from the air, which when stored in an open container leads to the appearance of water in solution. Water in paint is a guaranteed marriage when painting. Therefore, use only fresh, tightly closed acetone.
Secrets of the professionals
Experienced painters often add a little “slow” solvent to acetone when working in hot weather to prevent paint from drying out too quickly on the metal.
Petroleum products: Solvent, White Spirit and gasoline
There are often oil products in garages, such as solvent, white-spirit Or Kalosha gasoline. Can they replace the P-4? Solvent (oil) is close in properties to toluene, which is part of R-4. It dissolves bitumen resins and some synthetic materials well. For nitro-emals, the solvent is worse, since it does not contain ketones, but as a component of the mixture is quite applicable.
White Spirit is a heavy solvent. It evaporates for a very long time and does not dissolve nitrocellulose well. Use it instead of P-4 to dilute nitroemals categorically not recommendedSince the paint simply will not dry normally or will lie in a cloudy spot. However, for washing the tool from oil paints, it is perfect.
Gasoline "Kalosha" (solvent for the rubber industry) in properties closer to the solvent. It is quite active, but has a specific smell and flammability. In emergency cases, when you need to urgently wash fresh nitro-enamel from your hands or tool, it will cope. But to prepare the paint for application, its use is a lottery with an unpredictable result.
Below is a table of compatibility of different solvents with materials types to make it easier for you to navigate:
| Solvent | Nitroemali (NC) | Acrylic enamel | Oil paints | Cleaning the tool |
|---|---|---|---|---|
| P-4 (Original) | Great. | Good. | Bad. | Great. |
| Solvent 646 | Great. | Great. | Bad. | Great. |
| acetone | Okay (with risk) | Good. | Middle-Average | Great. |
| White Spirit | Bad. | Bad. | Great. | Good. |
| Solvent | Middle-Average | Middle-Average | Good. | Good. |
As you can see from the table, there is no universal soldier. Petroleum products are good for oil compounds, but for nitrocellulose, for which P-4 is created, they are weak without adding ketones.
White spirit and kerosene are not suitable for diluting nitro-emals, as they cannot completely dissolve nitrocellulose, which will lead to a defective coating.
Mixing and proportions rules
If you decide to prepare the analogue of P-4 yourself or use a mixture of available solvents, it is important to observe the proportions. The classic formula P-4 implies acetone content of about 12%, butyl acetate 26% and toluene 62%. It is clear that in the garage scales and measuring cylinders are rarely used, so you can focus on bulk parts.
To obtain a working composition close to P-4, you can mix solvent 646 with a small amount of pure toluene or solvent if the 646th seems too aggressive for your paint. The ratio can be 4:1. If only acetone and white spirit are available, this mixture will work poorly due to the lack of esters, but it will be useful for primary washing.
When adding a diluent to the paint, follow the rule: it is better to underdo than transfuse. Viscosity should be checked by viscometer or by experiment (on the test plate). Too liquid paint will flow, too thick will leave a shaver.
☑️ Quality check of mixture
It is important to mix the components in clean, dry containers. Getting water or dirt will nullify all efforts. Stirring should be thorough, but without intense stirring, so as not to saturate the mixture with air bubbles.
Safety and storage
All of the substitutes considered are highly toxic flammable liquids. Couples acetoneToluene and Solvent are heavier than air and can accumulate in lowlands, creating an explosive mixture. Working with them requires mandatory ventilation of the room. In a closed garage without an hood, working with large volumes of solvent is deadly.
Use personal protective equipment: a respirator with a carbon filter, rubber gloves and protective glasses. The skin of the hands quickly dries up and cracks from contact with these chemicals, and getting splashes into the eyes can cause serious burns to the cornea.
⚠️ Warning: Do not smoke or use an open fire in a room where solvent containers are open. Sparks from static electricity when transfusing liquid can also cause ignition of vapors.
Store replacements P-4 need to be tightly closed metal containers, away from heating devices and direct sunlight. Plastic canisters from under water for these purposes are not suitable - the solvent can eat the plastic or react with it.
For safe disposal of rags soaked in solvent, fold it in a metal jar of water and close tightly with a lid to prevent spontaneous combustion.
Compliance with these simple rules will allow you not only to perform the job qualitatively, but also to maintain health. Remember that chemistry does not forgive mistakes, especially when it comes to volatile and combustible substances.
FAQ: Frequently Asked Questions
Can P-4 be completely replaced with regular acetone from a pharmacy?
Technical acetone can be used, but a pharmacy often contains water and additives that will spoil the paint. Pure acetone dries too quickly, which will lead to defects in the coating. It is better to mix it with butyl acetate or use a 646th solvent.
Will gasoline be suitable for diluting nitroemali?
Conventional motor gasoline contains oils and additives that will leave a greasy film. Gasoline "Kalosha" (solvent) can be used for washing, but for diluting the paint under painting it is not recommended because of the risk of changing the properties of the film.
What is the difference between R-4 and R-12?
P-12 is intended for epoxy and perchlorovinyl materials, it is less volatile and has a different composition. Replace P-4 with P-12 can only be in extreme cases and only for perchlorovinyl paints, for nitro-enamels it is not suitable.
How to remove the smell of solvent after work?
It is necessary to arrange through ventilation. You can arrange containers with water, adding salt or activated carbon to them, they partially adsorb vapors. Ozone air purifiers are also effective, but they take time.
Can I store a diluted solvent?
Yeah, if you close the lid tightly. However, a mixture of different solvents may be unstable during long-term storage. It is better to prepare the mixture immediately before use or in volume for one shift.