Fiberglass over epoxy putty - Fiberglass becoming dry

I was building the keel of my trimaran with epoxy mixed with colloidal silica up to peanut butter consistency. Everything looks to go fine. After 40 kg of epoxy putty and while still wet, I placed two layers of 540g/m2 glass fiber and fill them with epoxy until they become transparent. On the top of it one layer of peel ply and allow it to dry. When I removed the peel ply everything looked fine.

However the putty in one area was not as I wanted and I took the decision to remove the glass in that small (50cm) area. When I tried to remove the fiber I was able to remove it by hand (pulling from the corner where I broke it) and also notice that the underside of the fiber was somewhat dry.

My two questions are:
It is normal that fiber would come out by hand? Was not easy to pull it but also was not extremely difficult.

It is possible in some way while drying that the epoxy putty "suck" some of the "clean" epoxy from the fiber on the top making it dry (it was not too dry, only some dry fibers on the under layer)?


Thanks in advance, Filipe

 

Did you put more another layer of epoxy on top of the epoxy putty before you put the first layer of 540g down?

That is important, as the putty doesn't really get up into the weave of the layer of glass.

 

Thanks for the answer. No, I just placed the fiber on top of the putty and wet it after. Each layer of 540g is biaxial making a total of four layers. I was looking today morning with more detail and In fact the most inner layer (in contact with the putty) it seams ok as the top layer. However the two middle layers looked like explained before.

Regards,
Filipe

 

Hi.

Laminates are weak in shear strength. It is not unusual if you can pull it off.
You say that you used Biax material - so your 4-layers are somewhat like 8 layers unidirectional with changing orientation of fibres. When you pulled only one day after application (no post curing I assume) the resin was not yet fully cured.

From your other description I read that the inner layers only look 'strange'. This does not match with a sucking theory. Did you consolidate the laminate, or just saturated it?

Low temperatures, humidity and amine bleach also could have contributed to a problem. But it is still a question if there is a problem at all.

 

Hello,
Thank you for the answer. Yes, it was just over a day. It was 2 layers making a total of 4 layers but the weather as been cold and wet over here. Over some time it seams better the laminate. I only saturate it and no post curing.
Regards,
Filipe

 

Not too late yet though: You can try to tape a plastic foil along the repair area and place a heating blower at one open end. It is a little like a wind tunnel with hot air. This is close to a post curing procedure. Before you continue later: wash the surface to remove the amine blush.
You can also spot-check at a few uncritival places to see if there is an improvement.