To thin water-based varnish, you typically use water.
Thinning water-based varnish is a common practice to improve its application and finish, especially in certain conditions.
Why Thin Water-Based Varnish?
Thinning helps to reduce the viscosity of the varnish, allowing it to flow out more smoothly. This can lead to a more even finish with fewer brush strokes visible. It is particularly beneficial:
- In higher temperatures
- When seeking better flow for a smoother finish
How Much Water to Add
Based on common practice and the provided reference, many water-based varnishes can be thinned with water up to 20%.
- Start slowly: Begin with a small amount of water, like 5-10%, and mix thoroughly.
- Test: Apply a small amount to a scrap piece of material to see if the consistency is right.
- Add gradually: Continue adding water incrementally until you achieve the desired consistency, not exceeding the recommended maximum (e.g., 20%).
Important Note: Always check the manufacturer's instructions on the varnish can first, as recommended thinning ratios can vary.
Mixing Process
When thinning:
- Measure the amount of varnish you plan to use.
- Calculate the amount of water needed based on the desired percentage (e.g., 10% of the varnish volume).
- Add the water slowly to the varnish.
- Stir gently but thoroughly until the water is completely incorporated. Avoid vigorous shaking, which can introduce bubbles.
Application Considerations
Thinning can affect how the varnish is applied and how it behaves.
- Multiple Coats: You may need to apply more thin coats to achieve the same film thickness as fewer un-thinned coats.
- Brush Choice: Using the right brush can also significantly impact the finish. As mentioned in the reference, a very fine synthetic bristle brush, like Golden Taklon, is often recommended for applying thinned water-based varnish for a better result.
Here's a simple breakdown:
| Action | Thinner | Amount | Purpose |
|---|---|---|---|
| Thin Varnish | Water | Up to 20% (typically) | Improve flow, smoother finish |
Remember, thinning should be done carefully and in accordance with the product's guidelines to maintain the varnish's protective qualities and appearance.
