Epoxy choices

[Howard]

Is there a consensus on which brand of epoxy is best to use for these stitch and glue projects? I've always used West System on my stuff.....and while nothing has blown up yet....everything I've done has had air hole pockets in it when I'm finished. They show up when you are sanding, and to get them out you have to sand off almost all of the covering. You can lay another filler coat over the clean sanded area....but then you have the air pockets again.

Graham's info suggests Raka makes an excellent product. Any others?

Perhaps this has more to do with my mixing and application techniques than brand of epoxy?[/i]

[Frank Hagan]

I like RAKA epoxy also. Its a medium thickness, and easier to mix at a 2:1 ratio (at least I find it easier!) I have also never had a problem with blush with it ... it just doesn't seem to have that waxy build up that I've heard about with West Systems.

I have not had the bubble problem you speak of, but I'm not sure if that's due to using RAKA or not. Maybe some others will chime in here with their experiences.

[Tom Lathrop]

Bubbles is not a result of the brand of epoxy.

To attempt an answer to your problem we need to know what the application is (coating or filet) and whether the epoxy is thick or thin, fast or slow hardener, whether any filler is involved and how you mix it.

Large bubbles should not exist in cured thin epoxy but are difficult to keep out of thickened epoxy like that used in filets.

[Howard]

The air pockets seem to be on just about anything.....from thin coatings brushed onto wood, to single layers of glass cloth...to multiple layers of cloth in a layup. You don't notice them much, if at all, when it kicks....but once you scrub the amine blush off and go to sanding, all these little pinholes show up.....and a high gloss paint like Brightside will show each and every one of them!

They really show up when doing something like backfilling an oversized hole to make an epoxy bushing. The bottom will be clear....the top almost frothy from all the bubbles. I normally leave it very "proud" and then sand it back down flush...hoping the bubbles will float far enough to the top to be in the surface that gets sanded away.

I'm using the West System resin with both 205 and 206 hardeners, depending on temperature. I prefer the 206 for anything above 60 degrees. It gives me more time to work and a nice clear finish. I normally don't mix more than a couple pumps at a time....usually in a butter tub or sour cream container...something wider than it is deep.....and stir/mix it for about 1 minute or so....fairly slowly. Then...if I'm using any kind of additive, I'll mix that until it all looks consistent....again...about a minute of slow stirring. BUT...it seems to me that it doesn't matter how slow I stir...I always get some bubbles in the mix.

At that point.....if I don't get it on my work piece....it won't be long before it starts to heat up....so I try to get it out of the mix cup before that happens. Either pouring it onto my piece....or brushing as fast as I can work.

I have not tried pouring it onto a plastic plate to really thin it out so it doesn't heat up and kick too fast. That might let some of the bubbles move on out. I've also not tried to "pop" the bubbles with a heat torch...fearing it would heat the mix too much and kick it off too fast....killing the mix.

Love the things can do with this stuff....but hate the pinholes.

[Charlie Jones]

That's very curious. I've used WEST since 1976 and have never had that kind of problem. I do get the occasional bubbling from either outgassing if the material heats up while it's curing, or from over working , such as rolling to much with a dry roller.

Otherwise, it just doesn't happen. There fore, I really can't give you an answer- I would suggest you call the Gougeon's, ask for Tech Support, and ask your question there. The have some extremely knowledgeable and helpful people there.

[Guest]

First question from me, by some chance are you iwping your surface areas down with a chemical before coating the area with resin? If so what are you using and what type of rag are you using for that purpose? Next, be very patient with resin coating, and that includes a slow hardener for most cases in hull glassing and recoating. This actually gives you more time to recoat without any additional prep work of the surface. The time that you think you maybe saving, maybe costing you in the rework process.

Next, after reading your comments on the shiny Brightsides, there are some issues with putting straight topcoat on resin without any primer, one being the real longivity of the gloss you are applying to the surface. Priming will help show any imperfections and will give you some buildup to protect your actuall glassed areas, or sealed areas by resin, that you have when using epoxy to seal the woods. There are methods to check the level or unfairness of the surface, that will show up with the high gloss paints. Next the Brightsides has some issues with holding up, if you only think you may get by with just a couple of coats on any surface area that you will be painting anyway.

[Howard]

In most cases....no wipedown. One project was a couple layers of glass light 2oz glass cloth over a bare foam core.....and with that I simply washed the amine blush off, then sanded and wet sanded the epoxy coat. When it was dry...I used the Brightside Primer (one coat), then two coats of Brightside White. Still....lots of little pin holes!

The most recent effort was a repair on the inside of a glass boat, where I put down about 6 mixed layers of cloth, mat and roving...using un-thickened epoxy....using a brush and spreader to move it around. Same kind of problem when it was done.

I do know I tend to put down too much epoxy on the cloth...at least that is something I watch out for. I then try to brush on one or two coats to fill the weave in the glass cloth. But those little bubbles are usually present when it's time to finish sanding the thing down.

Based on what you folks are telling me...it's not a problem inherent in epoxy....so it's probably something I'm doing different that is causing it. Time to experiment with some different techniques.

Howard

[Guest]

Sounds like it is outgassing to me. In the hull project, were you doing this in direct sunlight? Also this latest problem, depending on the time of day that you did the jobs, did you have a drastic change of ambient temperture> Have you been placing any heaters on the project before glassing and coating of the resin?

[Howard]

I've only experienced what I thought was true outgassing one time, and remarkably, that was the only time I can think of when the little pinholes in the finished project were not evident. In that case, it was laying a couple layers of glass cloth over the bottom half of a wooden rudder. The outgassing kept pinhead sized bubbles popping open like little bubbles from chewing gum. They kept opening and closing until the epoxy kicked.

Since then, I've been aware of time of day and temps and don't work when outgassing should be an issue. Also, on many of these projects, I'm not working with wood, so outgassing should not be an issue.

The instructions tend to be confusing (with nothing more confusing than trying to follow the instructions from Interlux on how to use their products). Anyway, West's instructions say you can coat the work with epoxy and then lay down the glass, or staple the glass cloth on and then coat with epoxy. One way you may have the wood suck up too much epoxy and leave the glass cloth starved....the other way...you may have too much epoxy and the glass cloth "floats" off. I've finally decided on using a thin coat of epoxy...of which most is sucked into the wood, then while it's still tacky...lay the glass down....then wet it out until the "color" or whiteness in the glass cloth goes away. Then use a plastic spreader to scrape the excess off. I like to leave it with a clear look to the glass cloth, but the weave in the fabric evident. I'll then add a coat or two to fill in the weave...often with 407 low density filler added in to make sanding easier.

I'm beginning to suspect that my pin hole problems must be in my mixing technique. I'll try a test batch with slow hardener poured out onto a plastic plate....so the bubbles have time to float off and pop.....and maybe use a torch to try to pop them....with a control on the same surface before all that to see if any of it makes a difference.

I think I'm also going to order a sample of the RAKA products to do a few tests with it to see how that works.

I appreciate all the help and advice!

Howard

[Guest]

Okay, I see that you are saying that you are using form of microballons. Pin holes are a common problem with both 407 and 410 in the West System products. We have switched to another produst that works well for faring the glass, with absolutely no pin holes left , and with little work in the fairing stage.

Without going into a long conversation, here is a link that discusses a product that many of us have switched to for fairing compounds. I know somewhere on this board, the produst has been discussed, but I cannot find it right now in short order. So take a read that you are not alone in your problem with pinholes.

http://www.classicmako.com/forum/topic.asp?TOPIC_ID=2204

Try this page for the product, Quick Fair, page 254, top right of the page.

http://www.hamiltonmarine.com/CatIndex3.html

[Ken_Potts]

Howard,

I think I'm seeing the same pinholes that you do. I've always assumed that it was either common to all epoxy (although I've only used West) or due to my self-taught mixing/application techniques.

I don't have any worthwhile input I just wanted to chime in as someone who's had similar results. I'll have to take more notice in the future of when the bubbles are better or worse. Unfortunately I'm pretty much shut down for the winter on the boat project so it'll be a while.

[Howard]

I'm beginning to understand what is going on to cause my pinholes.

First....I went through the RAKA site. Good information.

Then, I recalled that I had once bookmarked this site:

http://www.oneoceankayaks.com/Epoxresl.htm

More good information.

Yesterday I did a small test piece on a hard surface with WS and 106 hardener. I had small bubbles in the resin just from pumping it into the cup...and they never went away. Stirring it made more. BUT...I now know that I was doing this with "cold" resin....maybe 60 degree temps. It was thick and never got better...despite me working in a 65 degree work area.

On one test strip....I ran a blow torch over the top of the mix and watched the bubbles pop. BUT...that strip now has funny little lines in it from the heat or contamination from the torch....and whats even more bizarre, craters where the bubbles were. It took at least two hours at those low temps to kick. I'm plumb amazed the craters didn't level themselves.

So I suspect my problem is one of the low viscosity of the WS resins. I'm guessing that if I start off with it heated to 80 or 90 degrees to "thin" it up a bit, the bubbles may go away. The RAKA appears to be much more viscous (thin) and so bubbles with it are not as much of a problem. I'm going to order their test kit to give it a try.

You folks that are not having troubles with bubbles in the WS products may be working in warmer temps?

Thanks for all the help!!

Howard

[Howard]

Thanks for correcting me on the terminology. I'm doing that a lot these days. Saying what I mean in reverse. Deslexia perhaps?

I think I've got some ideas to work with to solve my bubbles problem. I've got a vacuum jar at home that is used with one of those food sealers and could use a 50 CC syringe to pull a mild vacuum with that, but that sounds kinda extreme. Better to go with a thinner epoxy to start with.

Now it's time to go to work. One of my kids asked what they could get me for Christmas. I suspect they were thinking of a shirt or tie or something. I told them 4 sheets of 1/4" Okume. It sounded like a reasonable request to me, but for some reason they all think I'm weird.

Howard

[Charlie Jones]

you mean Lysdexia???

Often when I'm working in a cold shop I will put the resin/hardener in my mixing container , then as I'm stirring I blow down into the container with an old hair dryer I keep in the shop. I keep heating and stirring till the epoxy thins before I try using it. Of course, I make my living in the woodshop so sometimes I HAVE to use epoxy when I'd rather not.

The ideas on keeping the epoxy /resin in a "warm box" is a very good one. The Gougeons recommend that in their boat bulding book. I have an old defunct chest style freezer that I store my epoxy (and wood glues) in during cold weather. A 60 watt light bulb in there keeps every thing toasty. Remember- you have to warm your wood up too or you've defeated your purpose. Very cool or cold wood will just cool the resin right back down to where you were.

[Scott Dufour]

For what it's worth, I use System Three epoxy with a bunch of thier fillers, and in my short 1 1/2 boat experience, I've not had a problem with pin holes, out gassing, or amine blush. (I keep looking for the blush, but I've never seen it show up.) Price is comparative to West.