What is the best way to make a water-based semi-transparent stain or clear sealer for wood?
Semi-transparent stains and clear coatings that exhibit long term durability over wood are difficult to make. Even the most UV resistant polymers have problems. UV impervious polymers allow UV radiation to pass through the polymer with little hindrance. The UV subsequently degrades the wood underneath the coating film. The result is flaking of the coating film from the wood because of the degradation of the coating-substrate interface. (It’s important to note that this is not because the coating degraded but because of the degradation of the wood). When formulating clears and semi-transparent stains for wood, it is very important to include ingredients that absorb or reflect UV radiation from attacking the wood substrate. For stains, utilizing transparent iron oxide pigments work very well in absorbing UV radiation. These pigments can be utilized in fairly high levels without imparting too much opacity. Absorbing UV radiation in a clear coating is much more difficult. You must use mate
