Firstly, any advice is greatly appreciated. This forum is an excellent example of how people can and should share expertise and knowledge.
I have built a hollow wood longboard, based on Jack Young´s technique. The board is complete and ready to glass. I have decided to use epoxy and painted on a thin coat straight onto the wood in order to seal it and prevent the resin soaking in when glassing. Is this correct?? Now I am ready for the laminate coat, I assume I need to use expoxy resin again as it will be on top of the expoxy seal. Could anyone give me any tips/ advice for doing a laminate coat onto wood with epoxy. I am sure there are threads on this but any quick guidance would be appreciated especialy in terms of what not to do.
I live in southern Spain and it is summer, night time temperatures are around 28 degrees at the moment. Does temperature affect epoxy resin as much as poliester?
Epoxy is rather temperature sensitive. Best bet is to use when temps are above at least 60 degrees F. I forget the chart but the cure rate speeds up as the temps rise. Some epoxies need a high temp for proper cure… check the label or contact manufacturer.
On the board - check for any part of the surface that appears dry. If this is the case, consider a second sealer coat. How long has it been since first coat? You should lightly sand the surface it’s been awhile - different brands may require some sort of surface preperation between coats anyway. Some epoxy brands have been formulated for easy fiberglassing. Some brands have a tendency to blush and that will require some surface prepping between coats.
Once you are satisfied that the surfaces are well sealed, go ahead and apply fiberglass as usual using a squeegee to spread the epoxy and scrape off any excess. Don’t get too carried away on this step. It’s a wood board and saving weight won’t be a big issue - just get the cloth smoothed out, bubbles removed, and try to eliminate any pooling of the epoxy on the surface. Once cured, prep if necessary, apply a tape ‘apron’ around the edge (to eliminate unsightly drips) and brush on a fill coat. This should be sanded after complete cure and some sort of clear coat applied as a finish. Epoxy can be used as a final coat but may not provide very good UV protection. There are some urethane-based clear coats available that are better at that.
As always, avoid touching any surfaces with bare hands between coats - a likely cause of fisheyes. Avoid surface contamination period.
Depending on how you want the color to end up, I have had good luck applying epifanes marine high gloss varnish as the final coat over epoxy, i.e., after lamination and an epoxy fill coat. I use a roll and tip method to get it smooth. Also I have only done a couple of balsa skin boards, so take my advice, with that in mind, but I found a falling temp is best.
BB30, has perfected applying a spray on two part urethane.
If your board is already strong why bother with glass? There are a million and one ways to seal wood. For instance PVA wood glue is an excellant sealant dispite popular opinion. If your board is faired out and strong you don’t need to go through endless hours of work to make it look good. After many years of bashing my head up agaist this particular wall I now fair my wood surface to perfection and use some off the shelf PU spray can. I’m currently using Cabots exterior clear marine grade Satin finish… Don’t know if you can get that in Spain but once again if your surface is faired out well and good it makes an excellant finish and saves hours upon hours of unnessecary labour. Oh and don’t get too hung up on UV protection. Who leaves their board out in the burning sun all day long every day of the year.
Hope this helps. Good luck and fair weather;) PS and BTW what sort of wood are you using?