FishyFish Tolman Alaskan Skiff and Boat Building Forums

epoxy is epoxy, there should be no difference in adhesion, but if unsure do a test. As for the scarf, you can go either way. Sometimes depending on the timber, you can glass first then fill, or fill then glass over. I am a fan of filling first, but if you aren't careful, you can sand into the timber creating high spots (epoxy filler), because the timber sands easier, so it becomes a chasing game. best to coat with epoxy and leave it to harden up before filling. Make sure that you have a wide fill over the scarf so that it will blend in. You can also do a fill, rough sand up, glass over, then finish off fairing. There is a danger that you may end up sanding off your glass this way! As for untreated ply - all marine grade ply is untreated, and you strictly should not use treated, as the chemicals used are not user friendly to epoxy. I am not saying it won't stick, it just wont be as good, also any screws, nails, bolts etc that are left in treated timber, might react and corrode.

use a long board to sand off!

les

I've used two different brands in the past on the same boat with one caveat:

Make sure it is fully cured, cleaned, and sanded before using the second brand.

You can't get a chemical bond between different brands and I wouldn't want to try to due to different formulations. Other than the above precaution, you should be good to go. Oh, one more thing, when I say fully cured, I mean more than 72 hours total time above 65* F (~18* C for the sensible world). That doesn't mean that you have to have 72 straight hours above the above temperature, but instead that much time above broken up into several days if need be.