To spray DiamondFinish Clear, thin it 5 to 30 percent with KBS #1 Thinner or Xylene. The key is using a thinner with a slower evaporation rate than standard paint thinner. Fast evaporants cause the coating to dry too quickly during spray, leading to orange peel, dry spray, and poor flow-out. This guide covers thinner selection, thinning ratios, and spray best practices.
Why Slower Evaporants Matter
DiamondFinish Clear is a moisture-cured urethane that relies on solvents to maintain proper viscosity and flow during application. When you spray, the coating is broken into tiny droplets that must travel through the air, land on the surface, and level out before curing begins.
If you use a fast-evaporating solvent (like lacquer thinner or cheap generic paint thinner), the solvents evaporate during flight and after landing. This causes the coating to:
- Dry too fast and fail to level properly, creating an orange peel texture
- Lose viscosity mid-spray, resulting in dry spray and spitting
- Cure unevenly across the surface, leaving a dull or mottled finish
- Lose adhesion and durability because it did not have time to flow and cure correctly
A slower evaporant keeps the solvents in the coating long enough for it to level, flow, and cure properly, resulting in a smooth, glossy, durable finish.
Thinner Selection: KBS #1 or Xylene
You have two options:
| Thinner | Notes |
|---|---|
| KBS #1 Thinner | Specifically formulated for KBS topcoats, with the ideal evaporation rate and solvency. This is the recommended choice. |
| Xylene | A pure solvent with a similar evaporation rate to KBS #1 Thinner. Available at most hardware stores and automotive suppliers. A reliable substitute if KBS #1 Thinner is not on hand. |
Do not use lacquer thinner, acetone, MEK, or other fast-evaporating solvents. They will cause application problems.
Thinning Ratios and Spray Preparation
Start at the lower end of the range and add more if needed:
- Measure your DiamondFinish Clear. Pour the amount you need into a spray pot or container. Let's say you measure 1 quart (32 ounces) as an example.
- Start with 5 percent thinner. Add 1.6 ounces (5% of 32 oz) of KBS #1 Thinner or Xylene. Stir thoroughly.
- Test spray on scrap material. Spray a small area and observe:
- Does it atomize into a fine mist?
- Does it flow and level smoothly after landing?
- Is the pattern consistent and even?
- Adjust incrementally. If the spray pattern is still too thick, add another 2-3 percent thinner and test again. Repeat until you achieve smooth atomization and flow.
- Do not over-thin. If you exceed 30 percent thinning, you risk losing film build and gloss. Thinner coatings may require more passes to achieve coverage.
Spray Application Tips
Once your DiamondFinish Clear is thinned and ready:
- Strain the coating. Pour through a fine paint strainer into your spray pot to remove any debris or sediment that could clog the spray gun.
- Use proper spray equipment. Follow the application directions for spray gun type, air pressure, and technique.
- Apply thin, even coats. Multiple thin coats are better than one heavy coat. Heavy coats may drip, sag, or cure poorly.
- Allow proper flash-off time between coats. DiamondFinish Clear is moisture-cured. The exact time between coats depends on temperature and humidity (see directions).
- Do not spray in extreme conditions. Avoid application in direct sunlight, high heat, or very low humidity. Ideal conditions are 55-82 degrees F and 30-85% relative humidity.
Frequently Asked Questions About Thinning DiamondFinish Clear for Spray
How much should I thin DiamondFinish Clear for spraying?
You can thin DiamondFinish Clear between 5 and 30 percent when spraying. Start at the lower end and add more if needed for proper spray atomization and flow-out.
What thinner should I use for spraying DiamondFinish Clear?
Use KBS #1 Thinner, which is specifically formulated for KBS topcoats and has the proper, slower evaporation rate. Xylene can be used as a substitute when KBS #1 Thinner is not available.
Why do I need a slower evaporating thinner?
Fast-evaporating solvents cause DiamondFinish Clear to dry too quickly during spray application, leading to orange peel, dry spray, poor flow-out, and other finish defects. A slower evaporant allows the coating to level and cure properly.
Can I use standard paint thinner for DiamondFinish Clear?
No. Standard paint thinners typically evaporate too fast and will cause application problems such as orange peel and dry spray. Use KBS #1 Thinner or Xylene specifically.
Conclusion
Spraying DiamondFinish Clear successfully comes down to proper thinner selection and thinning ratio. Use KBS #1 Thinner or Xylene, thin 5-30 percent, test on scrap, and apply thin, even coats in moderate conditions. The result will be a smooth, glossy, durable finish. For complete spray setup and technique details, see the application directions.
