Glassed the EPS bottom with two layers of 6oz, that added slightly less then 2 lb to the board so approximately 1lb for each 6oz layer, right. I glassed the dcell deck with one layer of 6oz plus a 4oz tail patch…this added two more pounds!!! AARRRGGGGHHH!!
I could feel the resin being sucked in when trying to spread it…in a flash I used 12 oz of RR and only about 70% saturated. I violated my own rules…test…never again…cant always trust what you read…oh well, back to the drawing board
I was just going to purchase some divinycell. This has me a little concerned (expecially since I’ve heard the glass slides all around. I wonder if it would have worked better using a wetout table.
Sealing the foam with a slurry is not highlighted enough on this subject.
The process is highly recommended in aeronautical applications, as it helps fabric to adhere to the surface, and stops resin soaking into foam like a sponge.
Your resin/fabric ratios will also be much easier to achieve, saving all that excess weight, and the laminate to foam bond is enhanced.
Divinycel should be sealed before laminating or it’s sponge like character really comes into play. I usually seal with the same spackling compound as I use with EPS. When sealed it comes out fine.
I’ve never had divinycel take on water, it’s cell structure is just kinda large and this takes more resin to fill unless you seal it… Cobra has been using D-cel for years but there’s talk of them swiching to something else. Mostly because of supply issues though.
PVC foams are plastic. Plastic does not absorb water. They are closed cell. So the resin, water etc will only go as far as the first layer of open cells. It does help to seal the cells before laminating. Over the years I have worked for a number of Hi Tech yacht builders. We always sealed the foam. Usually with a mix of Q-cell and aerosil mixed with what ever resin system we were using. The dryer the mix the lighter. Squegeed on. platty.
Actually plastics do absorb water, but thats not really an issue with surfboards, some nylons can take up to 20% their own volume.
Where you plane or sand the surface of a foam, even closed cell, you open up the bubbles in the material. Adding microfibres or ballons to screed the surface blocks the “pores” in the foam, meaning it won’t soak up so much resin. Degassing and annealing is also a good idea.
New Divinycell coming out right now (I think H45 will be 1st) has a much smaller sell structure. Night and day. The resin is only going into the exposed cells. The new cell structure will help a lot.
Lead time for Divinycell if not bought off the shelf somewhere is currently 12 weeks.
This may be off topic, but… does anyone or has anyone tried prepregs? Obvious advantages are that with decent debulking and probably a gluefilm you could avoid to much uptake of matrix into the core, you could also do top and bottom in one hit.
