You can generate a smoother finish free from ugly brush and roller marks by diluting your gloss paint before application. Select the appropriate thinning agent based on the paint that you're using. If the paint has a gloss sheen, you'll need to use the right tool to encourage even distribution, or you'll end up with an ugly, uneven finish that appears shinier in some spots than in others. To thin gloss paint and preserve a uniform sheen, use a power drill equipped with a mixing paddle.
Pour 9 litres of gloss paint into the clean plastic bucket. Make sure the bucket is completely free of old paint chips or dirt.
Add 120 ml of white spirits to the paint, or 10g per litre.
Fix the mixing paddle to your power drill.
Insert the paddle into the paint. Turn on the power. Mix the gloss paint and white spirit together; raise and lower the paddle approximately 5 cm as you stir to promote uniform mixing. Continue to stir for five minutes.
If you are working with a water-based paint, use water instead of white spirits.
Don't try to dilute gloss paint using a wooden stir stick; this may not do an adequate job of thoroughly mixing the paint sheen and could lead to a flawed finish.
Stop the power drill and wait until it comes to a stop before removing the paddle from the paint, or splattering will occur.