. What caused my glass to crack instead of dent? the location is the deck rail where I place my foot or knee when duck diving. I usaully get dents there but not cracks. Ray (Stingray) glassed this puppy for me and we where just wondering what was causing pressure cracks instead of pressure dents. I was told that glass will crack like this if the resin has been over catalized…the cracks seem to only be in the hot coat but not into the lam coat. There is minimal denting if any???..
Was the board glosscoated? Too much catalyst or a high ambient temp (or glassing in the sun) will sometimes cause shatters. Be glad there wasn’t any deep dents to go with shatters. To fix these, sand the board barely down to the weave in the shattered areas. Catalyze some hotcoat resin and have some straight styrene and an artist brush ready. Brush the shattered areas with a very light coat of styrene and hotcoat immediately before it evaporates. Sand and recoat if you need to level any dents. If this area is localized to your foot/knee when you duck, you might want to add a layer of 6 oz. over the hotcoat.
PeteC thanks ,no gloss coat on this one. I was planning on fixing it with 4 or 6oz patch.
Thanks for posting the picture Ben. This was only my third complete glass job and I do not have a Master glasser overseeing what I’m doing.
The board was laminated using UV cure catalyst and Hot Coated with standard poly resin and catalyst. No gloss resin just some Swaylock tricks to get the killer gloss coat look. Any input is welcome !
Thanks
Ray
Howzit stingray, I’ve seen that happen because of basting to thick over the bottom lam lap before laying up the deck. Aloha,Kokua
To Pete C…
“Too much catalyst or a high ambient temp (or glassing in the sun) will sometimes cause shatters.”
Ben and I discussed that maybe I used too much catalyst. San Diego county has not been warm this winter. Temps were between 60-70 degrees when hot coat glassing this board. I don’t remember for sure. I have been measuring my catalyst by counting how many drops not by percentage or CC’s.
10 drops per ounce seems to work on my repair jobs and that’s what I used on this board. Is that too much?
To Kokua…
I’m not quite sure what you mean by "Basting’.
Thanks
Ray
I use a 1% catalyst mix, which is 5cc per 16 oz for hotcoats. I use 1/2 % for lams. I think that 2% is too much in normal weather, but that’s just my opinion. I do use 2% on glosscoats though. 1 teaspoon per 16 oz will give you about a 1 to 1-1/2% ratio. You really need to use a syringe to measure with, especially with small batches. I’m in south OC and I’ll give you some if you can get up here; leave me a PM. I think what Kokua means on the basted lap is that if you get too much lam resin on the lap line, it makes a high edge. This becomes a stress line for the hotcoat and cracking can occur along it. I always grind this line down (cut or freelap) before the next lam or hotcoat.
Quote:
I think what Kokua means on the basted lap is that if you get too much lam resin on the lap line, it makes a high edge. This becomes a stress line for the hotcoat and cracking can occur along it. I always grind this line down (cut or freelap) before the next lam or hotcoat.
BING !!
The light just came on !
…thanks for the illumination on that , Pete ! [I too have had this problem on several of the last few boards I’ve made .]
ben
…this happend , like Kokua said, when youve got more resin than fiber ratio…
…also if you dont did a basting…
…when you free lap and not clean up well youll have this problem
Howzit chip, The trick is as you squeegee the rails just squeegee the excess rail resin past the lap so it will protect the foam when you take down the lap before lamming the deck. This way the resin is not thick but still protects the foam.Aloha,Kokua
It’s all starting to make more sense…
Now I need to PM Pete C and start shaping that short board blank that’s in my garage.
Laminations too wet. The more resin there is in a lamination the more brittle it is. Tle less resin there is the more flexible the lamination comes out. Try to make it drier next time… without making it too dry. It’s a balance and just takes some experience to get just right. From the look of the picture it looks like you’ve made one small error. Otherwise evertthing looks very good.