Resin- coating top of desk how-to?

[Steve Phillips]

Thanks for providing a great forum! I'm in the process of building a good size desk using a large chunk of cedar driftwood. I have the top cut and sanded flat, but running down the middle is a drepressed area that I plan to sandblast. I intend to fill the depression and the natural voids and cover the entire top with clear resin. I'm assuming polyester resin, but I actually have a lot more experience with epoxy resin. Probably epoxy would be overkill for this? In any case, I'm not sure if I should brush on one or more coats to seal the wood before I start pouring resin. There are some fairly deep and ragged voids in the piece, and I'm concerned about air being trapped, and possibly bits of debris floating up... I'll blast it all with air before I do any of this, but some junk may remain trapped. This desk has an extremely irregular perimeter, so cutting a piece of glass to cover the top is out of the question. Any suggestions? Oh- does it need to be one pour? Also, for the parts of the desk that are vertical driftwood,in a natural but sandblasted condition, what would be a good-looking finish? (NOT glossy resin!) Thanks for any ideas! Steve

[AlexS]

I've used epoxy casting resin (Araldite M) for filling voids. It sets clear with very little shrinkage, but you do have to be careful as it tends to bleed through any small holes under the effect of gravity. Perhaps you coulsd put a thin coat in first and let it set, then do the main pour.

It's fairly thin, so seems to fill voids quite well, and you can bring any air bubbles to the surface using a hot air gun. This doesn't seem to set it off any quicker. I usually build up a dam around the void with string and masking tape, and fill above the surface to allow for shrinkage. Shrinkage isn't great, but for large voids, you're probably better off doing two pours.

[derekcohen]

Steve

My experience comes from building and repairing windsurfers.

Epoxy resin would make a very durable finish. Frankly, I prefer epoxy resin to polyester resin as is is not only stronger but has a slower setting time on the whole (although this does depend on the catalyst you use), which provides for more work (read "error correction") time.

Always use thin coats, NEVER a thick coat. The heat build up will otherwise destroy your work.

Make sure that you use a clear, ultraviolet-safe resin. The colours of epoxy resins run from deep amber to yellow to clear. I like the West System (which has the benefit from offering an accurate pump system for measuring out the resin/catalyst ratio).

Regards from Perth

Derek

[Steve Phillips]

Thanks for the info, guys! This is the sort of advice I needed- I've done a lot with wood, but never anything like this. Variety is great, but... Steve