soft epoxy

I am glassing and restoring and old ash canoe paddle and have gotten to the stage where I thought I could do my finish sanding before the varnish. After 3 days I am still able to dent the epoxy with my fingernail and even scratch off a high spot that was sticking up. I had started sanding after 2 days with 220 grit before I noticed that it was still soft. No dust was produced and the epoxy piled up in soft patches that later hardened. The only thing that I can think of is that my mix ratio was not right. I have the west system and pump set with the correct pumps attached. My first epoxy and fiberglass application used one pump on each with very little left over. I repeated with 2 more coats and then I sanded and had good results. The surface was gray and very smooth. I then started building up the layers with epoxy and plastic applicator to get my 5 or 6 coats. After the next coat I had about half the epoxy left in the cup and going to waste. I decided to make half a mix the next and subsequent times. I measured the pump travel distance and divided it by 2 and made a mark. The next 4 coats I pushed each pump down to this mark and mixed the epoxy. I wouldn't think this would pose a problem but as this is my first epoxy and fiberglass project I'm not sure. Can anyone help me with this situation? Should I let it cure longer or is it never going to harden? What should my next step be? Thanks for any help.

8 replies:

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RE: soft epoxy

Have you tried applying some heat? What are the ambient temperatures like where you are? If some heat doesn't help, you may find some ideas from these prior posts.

http://www.clcboats.com/forum/clcforum/thread/8408.html

http://www.clcboats.com/forum/clcforum/thread/8301.html

http://www.clcboats.com/forum/clcforum/thread/5054.html

RE: soft epoxy

Thanks for the reply. I'm working on this in my garage in Tennessee. Right now our days are 95 degrees and nights are 78 degrees. The garage probably doesn't go above 85 degrees. By heat do you mean from a hair dryer or something else? Thanks for the prior posts. There are some good ideas there too. Anyone else have any other ideas? Thanks.

RE: soft epoxy

Why do you think you need 5 or 6 coats of epoxy?  Typically you would need one or two thin coats beyond a well applied first coat with the glass cloth.  You are adding so much additional weight that your paddle will become unbalanced and a chore to use.  Sand off everything until you get to a smooth finish just at the level of the glass cloth.  Use varnish from there.  Epoxy resin adds very little strength to the paddle beyond the first layer that actually contains the cloth.  Any more is just to create a smooth surface.  

A canoe paddle should be as light and balanced as possible.  The less epoxy the better! 

RE: soft epoxy

Thanks, Oxford Pete for your reply. Maybe I misunderstood the information I was finding on technique. Or maybe it should be different for a paddle. On CLC's tips for boatbuilders page I went to "Working With Epoxy and Fiberglass" and then "Filling the Weave". It says in the text "It may take two thick or five thin coats to finish filling the weave". I was applying very thin coats by using the plastic spreader as shown in the picture. After five coats I thought I could smooth it slightly by putting one more coat on. Right now I'm having trouble sanding anything off. With 220 and then 150 grit there was no dust, only "scabs" of epoxy that piled up in some places and then hardened. Should I just continue to try to sand? One previous post suggested using white vinegar to remove soft epoxy. Will this help in my situation? Thanks for any help.

RE: soft epoxy

If you're using west system I'd walk away for a week and see if it hardens. I wouldn't use vinegar because it will only make a bigger mess. Even with a poor retio mix it should harden eventualy. With five coats it's hard to think you don't have enough epoxy on. The idea of filling the weave is to fill enough to sand off the tops of the epoxy over each strand of glass down to the surface of the low spots between the weave. It's hard to explain but easy to do. Hope this helps. SEEYA Jack

RE: soft epoxy

My experience with the West pumps is that they draw a small air bubble at the beginning of their travel, so cutting the travel in half might give you a touch too little hardener - suggest measuring by weight for small batches. 

RE: soft epoxy

Thanks to everyone for your help. I applied heat with a hair dryer and then left it for a week. That's hard to do when you're wanting to finish. When I came back to sand I had dust flying everywhere. I got it sanded smooth and am now ready to varnish. Thanks again. You are helping build my experience base so that one day maybe I can be of help to someone else. See ya on the water!

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