Author Topic: Epoxy filler  (Read 2195 times)

Offline narvik

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Epoxy filler
« on: July 07, 2013, 12:08:50 PM »
Hi, two short questions.
A friend can help me with lots of epoxy filler, marine quality. Will be cheaper then using the same amount of resin and micro balloons or similar. Surplus from one of his professional projects.
1) Is every epoxy bonding with any other epoxy product or should I be careful? Is mixing brands OK?
2) I will need some filling/fairing due to a somewhat bad scarf. Is there any difference if I fill first and laminate afterwards? On the one hand I want to take care of the problem as soon as possible (then continue with a clean sheet :)), on the other hand I was asking myself if there is a stronger bond between untreated ply, epoxy and the glass, better to fill/fair later?

Thank you
Peter

Offline kiwi les

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Re: Epoxy filler
« Reply #1 on: July 08, 2013, 01:14:40 AM »
epoxy is epoxy, there should be no difference in adhesion, but if unsure do a test. As for the scarf, you can go either way. Sometimes depending on the timber, you can glass first then fill, or fill then glass over. I am a fan of filling first, but if you aren't careful, you can sand into the timber creating high spots (epoxy filler), because the timber sands easier, so it becomes a chasing game. best to coat with epoxy and leave it to harden up before filling. Make sure that you have a wide fill over the scarf so that it will blend in. You can also do a fill, rough sand up, glass over, then finish off fairing. There is a danger that you may end up sanding off your glass this way! As for untreated ply - all marine grade ply is untreated, and you strictly should not use treated, as the chemicals used are not user friendly to epoxy. I am not saying it won't stick, it just wont be as good, also any screws, nails, bolts etc that are left in treated timber, might react and corrode.

use a long board to sand off!

les

Offline narvik

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Re: Epoxy filler
« Reply #2 on: July 08, 2013, 04:34:46 AM »
Thank you Les,
good advice.
Peter

Offline LittleGoat

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Re: Epoxy filler
« Reply #3 on: July 08, 2013, 09:14:50 AM »
I've used two different brands in the past on the same boat with one caveat:

Make sure it is fully cured, cleaned, and sanded before using the second brand.

You can't get a chemical bond between different brands and I wouldn't want to try to due to different formulations. Other than the above precaution, you should be good to go. Oh, one more thing, when I say fully cured, I mean more than 72 hours total time above 65* F (~18* C for the sensible world). That doesn't mean that you have to have 72 straight hours above the above temperature, but instead that much time above broken up into several days if need be.