Acrylic paints have long been a standard in auto repair due to their durability, brightness and ease of application. But even professional compositions from PPG, Sikkens or Mobihel require proper dilution before use. Not only the convenience of work, but also the final result depends on the choice of solvent and compliance with the proportions: whether the paint will lay down evenly and whether it will not form smudges or shagreens.
Many beginners mistakenly believe that acrylic paints can be diluted with anything - from plain water to gasoline. In practice, this approach leads to delamination of the composition, loss of gloss, or even damage to the paintwork. In this article we will analyze what solvents are suitable for acrylic paints, how to mix them correctly depending on the task (base coat, metallic, varnish), and what mistakes are most often made when diluting.
We will pay special attention to the nuances of working with two-component acrylic systems, where in addition to the solvent a hardener is required. We will also consider alternative options for budget repairs and cases when the thinner can be made independently from available components.
1. Main types of solvents for acrylic paints
Acrylic paints for cars are divided into one-component (1K) and two-component (2K). The former are diluted only with a solvent, the latter also require a hardener. The choice of solvent depends on the type of paint, ambient temperature and application method (spray gun, brush, roller).
All solvents for acrylic can be divided into three groups:
- 💧 Specialized acrylic thinners - paint manufacturers (PPG, DuPont, R-M) produce branded solvents for their products. They guarantee compatibility and predictable results.
- 🧪 Universal solvents - suitable for most acrylic paints (for example, Solvent 646, R-12). Cheaper than branded ones, but require testing for compatibility.
- 💦 Water — used only for water-dispersed acrylic paints (rarely used in car repairs due to low durability).
Recommended for professional car painting specialized thinners — they take into account the characteristics of pigments and resins in a particular paint. For example, for PPG Deltacron suitable thinner DX330, and for Sikkens Autocryl — Sikkens Thinner 2020.
⚠️ Attention: Solvent 646 aggressive and can “burn” acrylic if the proportion is incorrect. It is used only for cleaning instruments or in extreme cases, diluted with water in a 1:1 ratio.
2. Dilution proportions: how not to spoil the paint
The standard proportion for diluting acrylic paint for a spray gun is: 2 parts paint: 1 part solvent: 10% hardener (for 2K systems). However, this value may vary depending on:
- 🌡️ Air temperatures — in hot weather (>25°C), add 5–10% more solvent to prevent the paint from drying too quickly.
- 🎨 Pigment type — metallics and pearls are diluted thinner (up to 1:1.5) so that the pigment is evenly distributed.
- 🔫 Pressure in the spray gun - at low pressure (1–1.5 atm) the paint is made thinner, at high pressure (2–2.5 atm) it is thicker.
For accurate calculation use viscometer (measures the viscosity of the paint). The optimal value for most acrylic paints is 18–22 seconds (according to DIN4 at 20°C). If there is no viscometer, check “by eye”: the paint should flow from the stick in an even stream, without interruption or dripping.
| Paint type | Proportion (paint: thinner: hardener) | Air temperature | Recommended pressure (atm) |
|---|---|---|---|
| Basic acrylic (1K) | 2:1:— | 15–25°C | 1.5–2.0 |
| Acrylic 2K (with hardener) | 2:1:0.5 | 20–30°C | 2.0–2.5 |
| Metallic/pearl | 1:1.5:0.5 | 18–25°C | 1.2–1.8 |
| Acrylic varnish | 2:1:0.3 | 15–25°C | 1.8–2.2 |
Critical error: adding hardener to one-component paint (1K). This will lead to instant hardening of the composition and damage to the spray gun.
3. How not to dilute acrylic paints
Some “folk” methods of diluting acrylic may seem to work, but in fact lead to coating defects. That's what strictly prohibited use:
- ⛽ Gasoline, kerosene, white spirit - destroy the binding resins, the paint will peel off.
- 🧴 Acetone - too aggressive, causes clouding and cracking of the layer.
- 🍺 Alcohol (ethyl, isopropyl) — evaporates too quickly, leading to porosity of the coating.
- 🚰 Tap water - contains salts and impurities, which appear as white spots after drying.
Exception - distilled water, but it is used only for water-dispersion acrylic paints (not for cars!). Water is not suitable for standard acrylic enamels, since it does not dissolve acrylic resins, but only dilutes them temporarily.
⚠️ Attention: If you accidentally thin acrylic with the wrong solvent, do not try to “fix” it by adding the correct one. It's better to recycle the damaged paint and start over.
4. How to dilute acrylic for different application methods
The method of applying the paint dictates its viscosity. Let's look at the three most common options:
Spray gun (HVLP, LVLP) - the most popular method in auto repair. The paint is diluted to viscosity 18–22 sec (according to DIN4). For metallics and pearlescents, the viscosity is reduced to 15–18 secso that the pigment does not settle in the tank. Inlet pressure - 2.0–2.5 atm, at the outlet (at the nozzle) - 0.7–1.2 atm.
Brush or roller - used for local repairs or painting of small parts. The paint is diluted thicker: proportion 3:1 (paint: solvent). It is important to apply in thin layers to avoid smudges. For better spreading add 1–2% silicone additive (for example, PPG DCX61).
Airbrush - requires the most liquid consistency. Dilution proportion - 1:1 or even 1:1.5. Pressure - 0.5–1.5 atm. For an airbrush it is critical to use filtered solventso that the nozzle does not become clogged.
☑️ Preparing paint for application
5. Homemade solvents: when justified
If you have a limited budget or urgent repairs, you can make your own acrylic thinner. Main component - butyl alcohol (sold in hardware stores as varnish thinner). It is mixed with ethyl cellosolve (1:1) and add 5% distilled water.
Homemade thinner recipe:
- Mix 50% butyl alcohol and 40% ethyl cellosolve.
- Add 10% distilled water.
- Stir and let sit for 24 hours (to remove air bubbles).
This composition is suitable for one-component acrylic paints and varnishes, but not recommended for two-component systems. Its main disadvantage is the instability of its properties: drying time and gloss of the coating may vary from batch to batch.
⚠️ Attention: Homemade solvents are not suitable for painting visible parts of the body (hood, fenders, doors). They are used only for internal parts or temporary repairs.
What happens if you use a low-quality solvent?
Poor quality or unsuitable solvent can cause the following defects:
- Shagreen (uneven texture due to evaporation too quickly).
- Smudges (the paint does not have time to spread due to its high viscosity).
- Cloudiness (the solvent reacts with the pigment or resin).
- Peeling (poor adhesion due to residual oils or impurities in the solvent).
- Yellowness (when using solvents with a high content of aromatic hydrocarbons).
6. Common mistakes when diluting acrylic paints
Even experienced painters sometimes make mistakes that spoil the result. Here are the most common:
- 🔄 Mixing paint at high speed — leads to the formation of air bubbles, which after application remain as craters.
- ⏳ Failure to comply with holding time — after adding the hardener, the paint needs 15–30 minutes to “ripen” (induction period).
- 🌡️ Ignoring temperature — at +10°C the paint dries 2–3 times longer, and at +30°C it can dry right in the spray gun tank.
- 🧴 Using expired hardener — loses activity, the coating remains soft and sticky.
Another typical problem is wrong mixing order. Hardener is always added to the paint last, after the solvent. If you do the opposite, the composition may curdle.
Before painting completely, apply a test coat to a small area (for example, the inside of a door). This will help evaluate viscosity, drying speed and component compatibility.
7. How to store diluted acrylic paint
Diluted acrylic paint (especially with hardener) cannot be stored longer 24 hours - after this it begins to polymerize and becomes unsuitable for use. However, there are ways to extend its life:
- 🧊 Refrigerator — if you seal the container hermetically and put it in the refrigerator at +5°C, the paint will retain its properties up to 3–5 days.
- 🔒 Vacuum packaging - for this, they use special pumps or simply pour the paint into a smaller container, minimizing contact with air.
- 🧪 Component Separation — if painting is delayed, it is better to store the paint, solvent and hardener separately, mixing them immediately before work.
For long-term storage (months), the paint cannot be diluted. Optimal conditions for undiluted acrylic:
- Temperature: 10–25°C (no drops!).
- Humidity: no higher 60%.
- Container: original jar with a tightly closed lid.
If the diluted paint begins to thicken or form lumps, it cannot be “reanimated” by adding a solvent. This paint is disposed of because it has already begun to polymerize.
FAQ: Answers to frequently asked questions
Is it possible to thin acrylic car paint with water?
No, standard acrylic car enamels are not diluted with water. Water-dispersed acrylics (for interior work) - yes, but they are not suitable for body repairs due to their low resistance to moisture and UV radiation. For cars, use only specialized solvents.
How to dilute dried acrylic paint?
If the paint has dried in the can, you can try to restore it resuscitator for acrylic (for example, Liquitex Professional Acrylic Flow Release). An alternative is a mixture of butyl alcohol and ethylcellosolve (1:1), but the result is not guaranteed. In most cases, dried paint is easier to recycle.
Which solvent is best for metallics?
For metallics use slow solvents (for example, PPG DX330 Slow or Sikkens Thinner 2026). They give the pigment time to distribute evenly, preventing "mottling". The dilution ratio is 1:1.5 (paint:solvent).
Is it possible to mix acrylic paints from different manufacturers?
Theoretically, it is possible, but only if they are on the same base (for example, both are on acrylic-urethane resin). Test compatibility on a small area before mixing. Different brands of paint may have different drying speeds or reactions to the hardener, which will lead to delamination.
How to clean a spray gun after acrylic paint?
To clean, use the same solvent that was used to thin the paint. After rinsing with solvent, pass through the spray gun. pure white spirit (to remove residual resins), then water and soap. To simplify the process, you can use special cleaners, for example, PPG DX335 Gun Wash.