Clear thickener and/or filler?

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joatmon
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Clear thickener and/or filler?

Post by joatmon »

:embarassed Well, I went and installed my rope stem bands and mixed up a batch of milled fiber to fill in around the edge and to my surprise it turned grey. Does anyone have any ideas for a thickener or filler that would mix with epoxy and remain sort of clearish? I love the look of the rope at the stems and it seems a shame to spoil the neat look with a bunch of grey filler.
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Glen Smith
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Post by Glen Smith »

Fumed Silica or "Cabosil" is clearish. Not perfectly clear but rather a bit "cloudy" but definitely not grey. It produces a very hard epoxy and should be applied as smoothly as possible so it doesn't have to be worked too much once hard.
AlanWS
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Post by AlanWS »

If you want it truly clear, one way to do that is to use just epoxy. The way to do that is to carefully measure out resin and hardener, but not to mix them yet. Add half the measured resin to the hardener and stir well. Let it react for about as long as your epoxy usually takes to set -- it will get warm and thick, but won't harden. Now you can thoroughly mix the rest of the measured resin in, and you will have a thickened epoxy that will be clear, and will set up in the usual amount of time to make epoxy of the usual strength, but won't need filler to keep from dribbling out.

If you want it a little thicker, add a bit more resin in the first step, or for thinner stuff, add less resin in the first step. But make sure the measured ratio is as accurate as possible, and you mix very well.

Other options are the milled fibers sold by system 3 that make it a little whitish, rather than grey. They are a little clearer than the silica I've used. If you really want it clear, your filler needs to have little color itself, and you want the index of refraction to match your resin. That means fibers that behave one way in my epoxy may behave differently in yours. But the all epoxy solution of the first paragraph should work for anyone.
Alan
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joatmon
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good ideas

Post by joatmon »

I'm leaning towards the half resin mix method. I'm going to try some file shavings added to it to make it a little stiffer. thanks again, time to eat then back at it.
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Rod Tait

I'm with Alan

Post by Rod Tait »

For seams on bulkheads, I mix up a slow hardener and keep stirring it every so often until it becomes gooey and then run a bead with a gloved finger. It comes out perfectly clear. You need to keep an eye on the mix and stir it occassionally to know when it is just right to use. In volume, once it starts to kick off, there is only a small window of opportunity to get it on.
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joatmon
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Okay Rod, I'll try that next..

Post by joatmon »

The 1/2 resin and hardener method didn't work. Once it started to get warm, I added the rest of the resin and It really kicked off then. Luckily I mixed in a metal can and had a 5 gallon bucket of water ready. I ended up using filings from a batch that had dried from a few days ago mixed with a regular small batch. It didn't come out very nice. I think I'll give it a few days and then sand it and try Rod's procedure. I'm only mixing tablespoon size batches, 1 hardener and 3 resin. I would try the silica but I'm running out of $$$. By the way, she's coming off the forms and getting sanded (inside) Tues. Thanks again.
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Rick
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Post by Rick »

Noah's has milled and chopped fiberglass filler material which might make for a clearer paste. I didn't bother buying and just cut up some fiberglass cloth to about 1/16 strands and mixed that with epoxy. The fiberglass/epoxy is clear, but turns translucent with greater thickness. Small air bubbles are also there so some heating might help to get rid of those.

The glass/epoxy paste was used to build up an abrasion-resistant skid plate over and under the stems instead of the brass stem band, and it took on an amber tone from the wood underneath. Not a bad look, and easy to repair when the need arises.
AlanWS
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Post by AlanWS »

I'm very sorry I wasn't clearer. After the first mixing step, I should have said to let it cool (complete the hardening it can do) before adding the second part of the resin. This method is very much like that mentioned by Rod Tait, except that you slow down the completion of the cure by making sure the heat from the first part of the cure is not there to speed up the later part. If you mix it all at the same time, you will have even less time to work after it gets thick.

After the first mix, you can store the thickened hardener, and mix it later with the proper amount of resin. This is essentially the same thing as epoxy sold as glue.
Alan
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hoz
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what about regular2 part epoxy glue?

Post by hoz »

Sold in twin plunger packs. It's thick and clear.
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joatmon
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No problem AlanWS..

Post by joatmon »

Alan, no sweat. It was worth a try and I hadn't had any epoxy "kick" on me, so the experience was sort of helpful, as I know what to expect now if it does. The reaction can be pretty unsettling if you aren't ready for it. I may try it again later but I decided to flip the hull and get to shaping the inside, the woodworking is the fun part for me, all this epoxy stuff is really slowing me down. :laughing Thanks and again it's no problem.
An Irishman has an abiding sense of tragedy which sustains him through temporary periods of joy.
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