If alkyd paint thickens, does not adhere well to the surface or leaves brush marks, the problem in 90% of cases lies in the wrong choice of solvent. Alkyd enamels (for example, PF-115, GF-230 or Tikkurila Miranol) require specific solvents - universal white spirit is not always suitable, and aggressive compounds like acetone may destroy the structure of the coating. In this article, we will look at what solvent is needed for specific types of alkyd paints, how to mix them correctly, and what mistakes lead to damage to the material.
Key point: alkyd paints are divided into oil (based on alkyd resins with added oils) and glypthal (with phthalic anhydride). The first ones are better to dilute solvent or S-50, second - xylene or specialized compounds such as R-4. Using an unsuitable solvent can lead to paint delamination, loss of gloss, or even corrosion of the metal under the coating (relevant for cars). Next is a detailed analysis with compatibility tables and practical tests.
1. Types of solvents for alkyd paints: how they differ
All solvents for alkyd enamels are divided into three groups by chemical composition and evaporation rate. This determines how the paint will behave when applied and dried:
- 🔹 Hydrocarbons (white spirit, solvent, kerosene) - universal, but evaporate slowly. Suitable for thick paints and work in hot weather.
- 🔹 Aromatic (xylene, toluene) - aggressive, evaporate quickly. Used to dilute glypthal enamels (for example, GF-230).
- 🔹 Mixed (R-4, R-646, S-50) - combined formulations with the addition of alcohols or ethers. Optimal for car repairs as they do not leave streaks.
Important: white spirit - the most popular, but not always the best choice. For example, for paints with a high content of alkyd resins (such as Hammerite) it may cause clouding of the coating. In such cases, manufacturers recommend specialized solvents the same brand.
2. Compatibility table: which solvent for which alkyd paint
In order not to make a mistake with your choice, focus on the type of alkyd paint and its purpose. Below is a verified compatibility table for popular brands:
| Paint type/brand | Recommended solvent | Dilution ratio | Features |
|---|---|---|---|
| PF-115, PF-266 (for metal/wood) | White spirit, solvent, R-4 | 5–10% of paint volume | When diluted >15% it loses gloss |
| GF-230 (primer-enamel) | Xylene, toluene, R-646 | 10–20% | Dries quickly, requires 2 coats |
| Hammerite, Dulux Trade (imported) | Hammerite Brush Cleaner, Dulux Solvent | According to the manufacturer's instructions | Incompatible with white spirit! |
| Car enamels (alkyd) | R-12, S-50, xylene | 15–25% | Thin immediately before painting |
Critical Warning: Paint based pentaphthalic resins (for example, PF-115) when diluted acetone or 646th solvent may curl up. This irreversibly damages the material.
3. How to properly dilute alkyd paint: step-by-step instructions
Even the right solvent can ruin the paint if the mixing technology is not correct. Follow this algorithm:
- Check thickness. If the paint does not flow off the brush or roller, it needs to be diluted. Optimal consistency: like liquid sour cream.
- Add solvent in small portions (5–10% of the paint volume), mixing thoroughly after each. Use
mixer at low speed(400-600 rpm) to avoid bubbles. - Test on an unnecessary surface. Apply some thinned paint and check:
- 🔸 Is there any separation or clouding?
- 🔸 Does the layer lay evenly?
- 🔸 Does the drying time correspond to the stated one (for alkyd paints - 6–24 hours).
nylon stocking or a special paint filter to remove lumps.Added solvent according to the compatibility table |
Mixed the paint without creating bubbles|
Tested on a rough surface|
Filtered the mixture from lumps|
Prepared the surface (degreased, primed)
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Optimal temperature for dilution - 18–25°C. At a lower temperature, the paint thickens; at a high temperature, the solvent evaporates too quickly, which leads to uneven coverage.
4. Errors when choosing a solvent and their consequences
The wrong solvent can not only deteriorate the quality of the painting, but also completely ruin the material. Let's look at typical mistakes and their consequences:
- 🚫 Using acetone for PF paints → the paint curls and flakes form. Reason: acetone dissolves alkyd resins too aggressively.
- 🚫 Diluting imported enamels with white spirit (for example, Hammerite) → loss of adhesion, peeling after 1–2 months.
- 🚫 Exceeding the permissible solvent proportion (more than 25%) → the paint loses its strength, cracks appear after drying.
- 🚫 Storing thinned paint more than 24 hours → the solvent evaporates, the paint thickens, and films form.
What to do if the paint has already curled?
If alkyd paint has curdled after adding solvent, you can try to restore it:
1. Pour the mixture into a clean container and add 10% original solvent (what is indicated on the can).
2. Mix with a mixer at medium speed for 5-7 minutes.
3. If lumps remain, strain through gauze folded in 4 layers.
4. Test on an unnecessary part. If the structure is not restored, the paint will have to be disposed of.
⚠️ Attention: If after painting there are signs on the surface white stains - This is a sign that the solvent has evaporated too quickly (for example, when using xylene in hot weather). The only way to fix it is by sanding and repainting.
5. Solvents for alkyd paints in car repair: nuances
When painting a car with alkyd enamels, the solvent requirements are stricter than in everyday life. The important things here are:
- 🔧 Evaporation rate. Suitable for use in a paint booth R-12 or S-50 (average speed). It is better to use in a garage without ventilation white spirit, but with an increase in drying time to 48 hours.
- 🔧 Primer compatibility. If the primer is acrylic and the paint is alkyd, the solvent should not contain xylene (it corrodes acrylic).
- 🔧 Ambient temperature. At +10°C and below, alkyd paints thicken - a dilution of 10–15% more than standard is required.
For two-component alkyd enamels (with hardener) solvent is added only after mixing the components. Proportions:
paint: hardener: solvent = 2: 1: 0.5–1.
When painting a car with alkyd enamel in hot weather (+30°C and above), add to the solvent 5% evaporation retarder (for example, Retarder from PPG). This will prevent orange peel and bubbles from forming.
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6. How to replace solvent in emergency cases
If you don’t have a specialized solvent at hand, you can use temporary analogues - but with reservations:
| No solvent | Temporary replacement | Limitations |
|---|---|---|
| White spirit | Kerosene (refined) | Dries slower and may leave greasy stains |
| Solvent | Gasoline "Galosha" | Only for oil-based alkyd paints, not for cars! |
| Xylene | Solvent 647 | Not suitable for light colors (may turn yellow) |
⚠️ Attention: Replacing solvent is always a risk! For example, gasoline in metal paint may cause corrosion after 6–12 months. Use analogs only for temporary work (for example, painting a fence), but not for cars or furniture.
7. How to store thinned alkyd paint
Thinned alkyd paint can be stored no more than 24 hours in a tightly closed container. Longer - only if:
- 📌 Storage temperature: 5–15°C (for example, in a cellar).
- 📌 The container is filled to the neck (minimum air).
- 📌 Added preservative (for example, Sikkens Retarder).
If the paint has been stored for longer than 24 hours, before use:
- Remove the formed film.
- Add 3-5% fresh solvent and mix.
- Filter via
nylon filter 100 microns.
Alkyd paints are sensitive to the type of solvent. Universal rule: use the solvent indicated on the can. If there is no marking, focus on the type of resin (pentaphthalic → white spirit, glyphthalic → xylene). For car enamels, choose only specialized compounds (R-12, S-50).
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FAQ: Frequently asked questions about solvents for alkyd paints
Can alkyd paint be diluted with water?
No. Alkyd paints are made from organic resins that do not dissolve in water. Adding water will lead to delamination and deterioration of the material. Exception - waterborne alkyd enamels (for example, Tikkurila Temadur), but they require special diluents rather than plain water.
Why did the paint become dull after thinning?
This happens due to:
- Exceeding the permissible proportion of solvent (more than 20%).
- Using a solvent that is too aggressive (for example, acetone for PF-115).
- Applying paint to an unsuitable primer (for example, alkyd enamel on acrylic primer without an intermediate layer).
It can only be corrected by sanding and repainting with the correct solvent.
Which solvent is best for alkyd paint for rust?
For anti-rust paints (e.g. Hammerite or Nerzhalux) manufacturers recommend own solvents:
- For Hammerite — Hammerite Brush Cleaner & Thinner.
- For domestic paints - R-4 or white spirit (but not more than 10%).
These paints contain corrosion inhibitors that are destroyed upon contact with aggressive solvents (xylene, 646).
How much solvent should I add for the spray gun?
For spraying alkyd paints through a spray gun, the proportions depend on the type of equipment:
- HVLP spray gun: 20–30% solvent (e.g. S-50 for car enamels).
- Conventional spray gun: 15–20%.
- Airless spray: 10-15%.
Important: before refueling the spray gun be sure to filter paint through filter 100–200 µmto avoid blockages.
Is it possible to mix alkyd paint with nitro paint?
No, this is strictly prohibited. Alkyd and nitrocellulose paints have different chemical bases:
- Alkyd - based on resins and oils.
- Nitro paints are based on cellulose nitrate.
When mixed, a chemical reaction will occur and the paint will curdle or lose adhesion. Exception - specialized transitional soils, but they do not guarantee the durability of the coating.