Technical, Techniques, Hints, and Tips > GRP & Epoxy

Tips for newbie to glassfiber/epoxy issues

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ahdguy:
I've started a build and come across a few issues some self inflicted, some not. 
Firstly I made the mistake of sanding a coat of epoxy then not removing all the dust out of small cracks. I assumed the resin would seep into the cracks - it doesn't so there are a couple of white lines. 
- Suggestions on fixing this? Can I dremel out the line and fill with epoxy? Or do I have to sand away to bottom of the crack?

Second issue is that I've been really careful with the stern planking - no gaps etc, but the fiber glass has faint white patches here and there - yet it was soaked in resin (and if anything I left excess resin on it).   Any ideas on what would cause this? Greasy on fingers handling the glass fiber?  Debating if I need to sand the whole sheet off and start again : (

(So much sanding)


Also can I ask how you get around keeping glass fiber flat around sharp edges? I find it tends to 'bubble up' around the edges.

Subculture:
Wood is very absorbent, and will absorb resin from the laminate before it cures. What you should have done is give the wood a light coat of epoxy resin (some people thin the resin with isopropyl alchohol, but I don't bother), and allow that to dry for 12 hours or so. This seals the wood and you can then apply your resin and glass over that.

Sadly I do think you will have to sand it back and start over if this is going to be cosmetic.

For the areas with white lines, you should be able Dremel in and backfill with resin.

grease or other contaminates tend to cause fish-eying rather than white patches. Also if you laminate on a day with a lot of humidity that can leave a milky finish in the resin. I tend to put epoxy work in a hot cupboard, or a hot box. It cures really nicely that way.

ahdguy:

--- Quote from: Subculture on February 07, 2017, 10:29:02 am ---Wood is very absorbent, and will absorb resin from the laminate before it cures. What you should have done is give the wood a light coat of epoxy resin (some people thin the resin with isopropyl alchohol, but I don't bother), and allow that to dry for 12 hours or so. This seals the wood and you can then apply your resin and glass over that.

Sadly I do think you will have to sand it back and start over if this is going to be cosmetic.

For the areas with white lines, you should be able Dremel in and backfill with resin.

grease or other contaminates tend to cause fish-eying rather than white patches. Also if you laminate on a day with a lot of humidity that can leave a milky finish in the resin. I tend to put epoxy work in a hot cupboard, or a hot box. It cures really nicely that way.

--- End quote ---


Strangely enough I had previously done a coat of epoxy to see how it would look without the glass.  Not great as it turns out, so I sanded smooth and then did a layer of glass on top so can't be resin-starved as the patch was sort of there on first applying resin.  (I think in hindsight I must have got something on the glass fiber as it had been laying about for a few days).   
Thanks for the tips (hot cupboard) will give that a bash tonight and see how that goes with the second coat.


Best

FrozenRabbit471:
I purchased the Smit Rodderdam for my first build. The chap at the hobby store said not to bother using anytime of wood filler, simply clean the planked hull, apply the glass cloth and epoxy, let dry, sand and paint. That doesn't sound right.


What say you

Tug-Kenny RIP:

It is easier to sand the wood containing filler than sand the epoxy coated cloth which makes breathing more difficult.   :}

Your choice

ken

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