We’ve all heard that resin/glass ratio is a significant factor in getting things done economically from both a materials usage and strength standpoint. Also, that poly resin and glass are maybe strongest at a 1:1 ratio, but no one seems to achieve that with hand lamination. I know I’ve tried to get the lam not too wet, not too dry… And I’ve seen laminations get too dry, with little air bubbles that the hot coat can’t or won’t fill.
So I wonder, not wanting to get into a full vacuum bag setup, has anyone tried laying a plastic sheet or similar over a dry lam so that you can press it down with, say, a roller, and get a real thin, low-resin-ratio lamination without the pinholes and tiny bubbles?
something I’ve done (with Epoxy) is to do the fold the glass up in a container thing and pour in the resin to soak up. Take it out, unfold it over the blank and using a squeege and brush spread it out. You will really have to work it. Your hand will get tired. It won’t be 1:1 but pretty darn close and really pushed in and spread thin. Add just what you need to get out the dry spots.
the topic recently came up over at the compsand form
this was just posted this morning:
Quote:
I have come across a trick to get smooth finishes on snowbaords, basically rolling a thin sheet of PVC foil over the wet deck prior to bagging. The pvc is such that you can easily manipulate bubbles out and it will then simply stick to the board and hold the surface of the resin smooth whilst you vac. The pvc foil is elastic and flex enough I am sure it could be used as a vac bag in itself and the stretchyness would make the rounding of the contours nicer… we will see soon as I got my roll of pvc yesterday…
never didi it with glass but did something similar making those sand petroglyphed resin tables back in 1970-1971 in shop class… I think I did my first swirl pattern over plywood this way back then too…
You can do it, but the hassle probably isn’t worth the effort. You can get a venturi fitting for your compressor and all the supplies for less than you think from http://www.acp-composites.com/onlineorder.html. I’ve done a few kiteboards bagged using their products and it goes pretty well.
I’ve bagged a few surfboards but really haven’t dialed the lay-up schedules. It comes out stronger but the problem is that the core foam is so weak it didn’t seem to make a huge difference. A light bagged glass job is still a light glass job. I even tried a composite with 1/8 corecell deck. It was pretty damm strong but the mistake I made was to use Xynole under the corecell and it came out heavy as a tank. I even tried to grind off the rail lap and pull it off just for the sake trying to salvage my experiment but bagging the cloth to the foam made it impossible to remove the corecell and glass without tearing out a large amount of the deck foam. So once again the board skin was stronger but the core wasn’t.
I’m sure Silly will chime in about compressive strength of wood and all and in one big circle you end up with a compsand.
Hey, laying a sheet of clear vinyl is how I’ve been rolling (standard wood seam roller) fiberglass on wood fins to saturate the epoxy and avoid the dreaded milkyness that comes with overworking epoxy and introducing too much air. It works pretty well.