Is Alumi-UV going to yellow or change color over time? Will Alumi-UV block UV light from the wood of my speargun? I am looking for a good protective coating to apply to the teak and purple heart speargun I am building. I need the coating to remain clear and protect my speargun wood from UV light. Uv light will cause the purple color of the purpleheart wood to change to brown over time. I also need it to do a good job of protecting the wood from damage. It will be used in salt water for spearfishing and be exposed to sunlight often.