So after a few months of delays getting my vacuum pump up and running, gettting all the materials and finding the time to shape my first balsa composite board, I have just finished my outer lam coats, and something doesn’t look quite right. The finish is a little splotchy. There are spots where the balsa clearly sucked up a lot of resin and other spots where it didn’t seem to suck up any at all. (Will try to get some pictures up in the next day or so.) Would like to get some guesses on what I did wrong.
First off, I have only shaped one other board and this is my first glass job ever so I wasn’t expecting perfection. If the board delams in a couple of months - no big deal as long as I learn something from the experience. And hopefully the advice on Sways will guide me to what I am doing wrong and I can correct it on the next one.
FYI. I didn’t seal the balsa. I weighed out my resin 1:1. On the bottom lam, I used a wet out table. But after seeing the splotchy results on the bottom, I decided not to use the wet out table for the deck lam. But I still got a splotchy result on the deck as well. I also noticed that nearly all of the paper towels I used in the vacuum bag came out bone dry, barely any spots of resin.
My guess is that because I did this by myself, I wasn’t very effecient at moving the wet cloth from the table to the board. I had to lift thecloth up off the board several times to get it to lay in the right spot. I think by doing this I transferred a lot of resin from the cloth to the balsa, creating spots with a lot of resin and spots with very little.
Maybe, I should have then used a brush and just lightly brushed the whole cloth with resin before I threw it in the bag?
More info - I am using Resin Research Epoxy with Additive F.
1/8th inch balsa on the bottom with 3 oz plain weave e-glass inside and outside.
3/16th inch balsa on the deck with one full layer of 3 oz inside and a 3 oz patch under my front foot and finally a single 3oz layer on the outside of the deck.
I’d wait until hotcoating before passing too much judgement. Once its a little shiny, the differences fade away a lot.
If you have obvious true dry spots, or bubbles that you can press a thumbnail in & they give, you’ll have to fix them. But if its just color & clarity for now, hotcoat & see what happens.
Warm your resin for the hotcoat & use your F.
BTW - I learned a nice trick for fixing air bubbles & sand throughs with epoxy after hotcoating - you may need it here Mix up a little epoxy & paint it on the spot with a brush. Put your cloth on, cut with round edges, no corners. Push it into the resin with the brush at 90* - don’t actually brush it, just tap it in. Re-wet the brush & tap on some more resin, it should seem just a little bit wetter than you’d really want, like if you were laminating you’d be worried that your glass will float up.
Then lay a piece of wax paper over the cloth & resin. Use masking tape, starting across the middle & working to both sides, bigger than the wax paper, to hold it on. Use it tight, so you’re squeezing the repair into the board & flattening out the resin.
When you peel up the tape & paper the next day, you’ll be absolutely amazed. On my latest board, I had to do about 6 spots like this, because I only had one layer of glass on the rails. 3 of them didn’t need any sanding at all before glossing, and the other 3 took about 30 seconds each to sand…
Did you bag on the glass? The reason I’m asking is that I find it very hard to do 1:1 then hand lay it up and get good results. My second guess would be that you moved a little too slow and it might have started to set up.
I just reread your post and it looked like you bagged on your glass. If this is the case I bet that you moved too slow.
I used the slow hardener which gives me 50 minutes before it starts to gel (doesn’t really kick). I am pretty sure I had the board in the bag by then, but you may be right.
Bart & Dan - how do you guys put wet glass on one side, flip it, put wet glass on the other side, and get it in a bag? Doesn’t the first side sag off or stick to the racks?
I mean, just physically, please describe how you did this.
Thats exactly the way that I use to do it. I would set up 2 different cups of resin (one cup for each side). I would wet out the bottom glass (I would fold it into a 2’x1’ package but it would work the same unfolded) carry it over to the board and unfold it and roughly smooth it out. Next I would mix up the second cup of resin to wet out the deck glass (I would save a little extra to wet out places on the bottom that still needed it). After the bottom was nice I would put the peel ply (cut short of the rails) on and flip the board (I have pvc stands so that it doesn’t stick, but I still put a little wax paper in between). Now I transfer the deck glass to the board, smooth it out (using the remaining resin from the wetout table), put the peel ply on so that it overlays the bottom peel ply, put some paper towels, and pop it in the bag. It there are little wrinkles at the laps the vac would take care of them.
I cover my racks with pvc tape and have also used a small offcut of polythene on each stand, when you flip, the bottom sticks to the polythene and not the stands so when you flip again to put on consumables, you can take the polythene pieces off and roll down the glass if it lifts.
I have had no problem with glass sagging off at all, I roll my resin on and use a minimum, if it was too wet I think it may sag?
Mix up a little epoxy & paint it on the spot with a brush. Put your cloth on, cut with round edges, no corners. Push it into the resin with the brush at 90* - don’t actually