Hello, I have just recently created an account… although I have been reading here religiously for the past 3 years. Thanks to all who contribute to the discussions here so that folks like me have been able to take part in this fascinating craft. I have learned so much and am currently working on my 5th board.
I don’t wish to start any sort of “this brand” is more UV stable than “that brand” …but I know that some brands of epoxy have “UV stabilizers” added, and I have some specific questions about what it is for.
Is this to prevent UV light from making the epoxy weaker over time, or is to just prevent yellowing?
Is it to protect the epoxy itelf, or the foam underneath?
Is EPS foam effected by UV light like PU? again does it become weaker or just turn yellow?
Does adding pigment to the lamination coat act like as a UV protectant by either blocking, absorbing, or reflecting light?
Does painting over the lamination protect against the effects of UV?.. is that why alot of mass produced epoxy boards are painted???
EPS holds up pretty good to UV. Polyurethane turns yellow.
‘Epoxy’ boards tend to have bondo and primer under the paint. Sand the paint off a TufLite and gain a new appreciation for what’s at stake on clear and tinted laminations.
UV stable means the mechanical properties don’t change from exposure. Yellowing is a separate issue.
The UV stability refers to protection the epoxy may need, not the foam. Most epoxies do not block UV from the foam.
Polyurethane breaks down badly from UV exposure. EPS does not break down, but will yellow a little.
Yes. But you may want to run some tests to see if the protection is adequate. A UV blocking additive for epoxy is cheap and easy. So is adding a blocker to the sealing layer. You can also use a two-part clearcoat to block UV and make hotcoating faster and easier.
Yes. Yes. But non-yellowing UV stable epoxies are widely available today.
Blakestah - My mother told me that it is low self esteem that causes a man to make fun of another’s cerebellum For the record, the photographer caught me at a funny angle - I told him I wanted mid-sagittal. I believe my cerebellum to be of quite envialble size I do occasionally have trouble following driving directions however…
johnmellor, you are entirely wrong. Polyurethanes have good light stability, provided they are alaphatic polyurethanes. Epoxies have TERRIBLE yellowing and are very photoreactive. That’s why they are only used on indoor high performance applications such as floor coatings where they will not be exposed to UV or as primers for a topcoat such as a urethane.
…but I know that some brands of epoxy have “UV stabilizers” added, and I have some specific questions about what it is for.
For the record, the photographer caught me at a funny angle - I told him I wanted mid-sagittal. I believe my cerebellum to be of quite envialble size 
I do occasionally have trouble following driving directions however…