epoxy ??????

[SENSEI]

ok, here is the question
I am getting ready to change out my fishfinder and will be removing the old transducer.I just purchased a new Lowrance Elite-5X DSI. I need to fill the screw holes and hopefully there won't be any water intrusion. if so I will have to ream out the wet balsa and dry the holes out. then fill with epoxy. Everyone talks about the epoxy but I cannot find any reference to type of epoxy and the filler/thickener to use. I am ready to go to the marine store to buy what I need . someone like to guide me in my purchase?

[Sunbeam]

There are four or five "nationally known" good brands of epoxy. Probably the most likely to be found at the corner marine store is WEST System. Others are System Three, Raka, and MAS (plus some other lesser-known brands).

I've used all of the above except Raka and found them all to be fine. WEST has excellent customer support and it's easy to find at West Marine and other locations.

I tend to use System Three as it's what I started with, and the 1:2 mixture is easy to measure by volume (that said, I just got a digital scale and plan to start measuring by weight). System Three is sold by Fisheries Supply (probably along with others). But I have also used WEST quite a bit.

They do all work similarly. Basically, you mix resin and hardener (in careful proportions), then either use it "neat" or add fillers to give it the consistency and physical properties you want. For filling holes, I would most likely use neat epoxy to wet them out, and then add colloidal silica to thicken it. You could also use other thickeners, but this is one that works well. You'll want to wear a respirator while you are mixing in the CS, as it is very "flyaway" and not good to breathe.

So, a short list:

--Resin (WEST 105 or System Three General Purpose, for example)
--Hardener of the same brand (medium or fast in your neck of the woods now)
--Filler (e.g. colloidal silica/Cab-O-Sil (same thing)
--Mixing cups (you can make your own) OR
--mixing pumps that fit onto the epoxy containers, OR
--digital scale
--Mixing sticks (I use tongue depressors, cut one end off straight for cup scraping)
--Squeegee (I make them out of cut up water jugs for small jobs)
--Nitrile disposable gloves (put two or three on each hand, peel off as necessary; good to keep epoxy off your skin).
--Respirator (for mixing silica; may not be necessary if you use another filler)
--Blue tape or similar for masking off
--Clear packing tape can be useful
--Pipe cleaners or similar for wetting out holes
--Syringe(s) for filling blind holes (non-adhesive shrink tubing makes a handy extension).

There are a couple of other options on the epoxy:

1) If you are only ever doing a few small repairs, WEST make small "repair kits." I don't buy the kits, because they have silly things in them like one pipe cleaner, and two gloves (ha ha), but what I do buy are the "ketchup packet" refills that go in the kits. Basically, you open two packets, combine and mix them, and Voila, you have a small amount of neat epoxy. It is a small amount though, so for me they are something I carry traveling or on the boat, not something I stock for my base arsenal.

2) WEST also make a product called "610," that is basically epoxy mixed with silica in a caulking tube, with some fancy properties. It's expensive ($20 for a tube that is only half full), but.... after years of having an "I don't need these silly pre-made things; I know how to mix my own!" attitude I did try some just the other day. I have to say it's pretty slick, and a tube will probably join the "ketchup packets" in my kit. Somehow it is capable of wetting things out (they claim, but then they aren't given to wild claims), and also of being a thickened epoxy. I've just started using it, and I'm initially pleased but that's all I know so far. It's very easy to be tidy with it, and you can squeeze out just as much as you need, quite simply.

Hmmm, this may be more than you ever wanted to know, but a couple of other thoughts on filling holes, especially those beneath the waterline. I like to first overdrill them slightly, then reach in (with Dremel/115 bit/tiny sanding drum, or dental pick) and remove more core (back-cutting), so the hole behind the fiberglass is a bit larger than the hole in the fiberglass.

Then I put a piece of blue tape right over the hole, then cut the hole back out with an exacto knife. That saves either putting a dozen teeny pieces of tape around the hole and/or cleaning epoxy off later. Then paint the inside of the hole with neat epoxy and after that fill with thickened (you can thicken the same batch and fill right away)

Getting the epoxy to fully fill a blind hole (i.e. there is no other hole for air to escape from) can be a trick. If there are two or more holes close together (I just filled an adjacent group of four from a transducer, for example), I will sometimes try to connect them "behind the scenes." Then you can fill from the bottom with a syringe or Zip-Loc with the corner cut off (like filling an outboard lower unit), let the air come out the top hole and then when epoxy starts coming out, slap a piece of tape over that top hole and slowly withdraw the syringe from the lower hole.

If you are stuck with a blind hole though (especially if it's not very large in diameter), the best way is to use a syringe and try to get it in far enough that you are filling from the bottom of the hole outward - so that the air can escape. On the holes in my transom that I made for the trim tab plane fasteners, not only were they blind, but they were horizontal, and they had "caves" up above the entrance hole (where I had back cut). Talk about air wanting to be trapped! What I did was first of all put an ~1" long piece of tubing on the end of the syringe, so that it would reach the back of the hole. One problem solved. But I was still getting air trapped in the "upper cave." So what I did that worked was take another piece of tubing and put it in the hole alongside the syringe, with the inside end up at the top of the "cave." Then I started pushing epoxy into the hole with the syringe. Air came out the other tube for awhile and then finally just epoxy. It worked! When I re-drilled the holes for the fasteners (into the epoxy), there were no air pockets.

Sometimes if you get something filled just right, you can slap a piece of clear packing tape over it, then peel it off later and all is perfect. But more often the plug will be standing slightly proud or a bit sunken. Both of these are easy to deal with if you catch it in the "green" stage. This is when it is not sticky or "easily moldable" anymore, but when it is still slightly rubbery and you can dent it with a fingernail. At this stage if your fill is proud of the surface, you can slice it off neatly with a sharp chisel and you're done. If it's sunken, you can add more epoxy without having to prep and it will chemically bond (later you would have to wash off blush, sand for tooth, remove sanding dust, then add for a mechanical bond), then slice that off in the green stage and be done.

You can clean "wet" epoxy droozles off the boat with denatured alcohol or acetone, but once it hardens it's a bear to remove.

Okay, I'll stop now. At least I put the direct epoxy-shopping info right at the top

Sunbeam

[Bill K]

Sunbeam,
I sure hope you didn't copy right those instructions as I just copied them them and emailed them to myself for later reference.

Thank You

[mgarr682]

If you've never used epoxy go to the West System website:

http://www.westsystem.com/ss/

and check out the "How to Use/Use Guides" and "How to Use/Videos" sections. Also, the "Products/How To Publications" section as many downloadable PDF files explaining the use of their products. For information about the various thickeners/additives browse the "Products/105 System/Fillers" section.

The West System Repair Kits ("Products/Repair Kits") can be handy to have around for small jobs. They come with resin, hardener, a filler or two, small mixing cups an applicators. For larger jobs it is available in quarts, gallons and larger sizes and the fillers can be bought separately. The appropriate sized pumps which screw right in to the quart and larger containers (one for the epoxy and one for the hardener) make mixing much simpler and they can be reused.

For a few screw holes I might just use one of the Repair Kits if that was all I needed and had to go buy some. Years ago when I was building a few boats and repairing my boats and friends boats I bought it by the gallon. I found I used it for quite a lot of things unrelated to boats as well. The Repair Kits come with small mixing containers, brushes, gloves, etc., but I've used paper cups and disposable cups or bowls too. The kits are handy because they come with about everything you need to just fill a few holes. Keep some rags handy to wipe up drips.

The other brands work in the same ways and probably just as well as the West System stuff. West System and West Marine are two different companies. While West Marine sells West System Epoxy it is also available from a lot of different sources and often cheaper elsewhere. The last I bought actually came from Amazon.

[NORO LIM]

Sunbeam, thanks from me, too. And also thanks to Roger for asking the question. Just for my own peace of mind, I need a little more guidance. (I'm about to pull an old transducer off myself.)

I'm still not absolutely certain about the "wetting" of the surface with neat epoxy before the filling of the cavity. (I understand the claim about the West 610 premixed tube, but I'm using West's separate resin and hardener.)

Do I merely coat the inside of the cavity with epoxy as soon as I have mixed the resin and hardener, and then immediately fill with the same mixture? (Or, if I'm adding a thickener, as soon as I've done that.) Is there no wait between wetting and filling? I assume it's important that there not be too much wait!

[mgarr682]

[NORO LIM]

OK, maybe an even more basic question occurs to me as a result of this exchange. With a very small hole to fill, is thickener necessary or advisable?

Put another way, if I didn't use a thickener, would the "wetting" step be necessary?

[mgarr682]

[Will-C]

I don't do a lot of epoxy work. I have used both types and I don't think you need a lot for your job. When you price up all the items required for the U mix it set up you might think that the West SIX 10 two part tubes are a real deal at twenty dollars. The two parts are in the tube,you add a screw on mixing tube and place the tube in a caulking gun. The epoxy comes out that for me was the perfect consistency. I was redoing a threaded in type drain plug flange on our transom. Once your done unscrew the mixing tube replace the cap back on the two part tube and the reminder stays go to go and all you have to do is buy a replacement mixing tube. For me this stuff is the hot setup. I'm no epoxy cowboy so to each there own. It worked for me as after it hardened I drilled and put screws into it that hold my drain flange in place. I have a thread in bronze pipe plug so I would know if it was not holding up everytime I tighten the drain plug. I'm pretty sure it will seal up screw holes. I used painters tape to hold it in place while it cured.
D.D.

[mgarr682]

[NORO LIM]

[Sunbeam]

This is turning into a nice epoxy thread. It sounds like you have a lot of epoxy experience, Mike, and I'm glad you thought to mention the use guides, as I meant to but forgot. In addition to the one on WEST's site, System Three also has one called "The Epoxy Book" on their site. I like them both as I find it helps to get two perspectives on things. Whomever illustrated WEST's guide should get a medal, because..... I don't know what it is, but there is something about those clear, simple illustrations that makes it look so easy 'Course then you start doing it and discover it doesn't stay tidy like the illustrations

What was I going to say.... oh yeah, on the neat/filled. As Mike said, you want to go in with neat epoxy first, because it will soak in a bit and make everything bond better. If you just start with thickened it will harden into a dandy plug, but not really "become one" with the substrate as effectively - and you want that.

You can actually wait quite a while between the neat and the thickened. Normally there is no reason to, and no need to, but it can actually be a purposeful thing in certain situations - mostly when using cloth though. For example, when I glassed the underside of the lazarette openings, I let the neat epoxy tack up slightly before applying the cloth, and that way the cloth wanted to stick vs. drooping. Of course in a hole, even if it's "upside down," you can just pump the epoxy in and slap tape over it. But if you did need to delay, or got called away, or etc. then know you can still get a chemical bond as long as it's in the green stage (i.e. past wet/sticky, but still easily dentable with a fingernail). There's no set amount of time for this because it depends on temperature, humidity, hardener type, and how thick the epoxy is (thicker, like in a cup, heats up and cures faster). But again, there is normally no need to wait either, so you can do both operations back to back.

Another reason for using the thickened epoxy - besides the fact that it's less able to run back out of the hole - is that it's much stronger. Unreinforced epoxy is relatively brittle, but once you reinforce it with a structural filler, or with "cloth," then it's many times stronger.

On the 610: Yep, I think it's probably a good choice for many people and jobs (including me). You'd have to be a millionaire to build a boat with it, but for small jobs you may even save money. And it is really convenient and tidy. I did ask their tech department (twice!), "Really, it can wet out holes (say in balsa) as well as neat epoxy?" They said yes, and I tend to trust them, but I'm not 100% sure yet whether I would do that on critical holes or whether I would still want to wet it out with neat epoxy. Maybe I'll have to do some experiments (I'm actually going to use it today or tomorrow and will see how it works at wetting out.)

I sometimes actually fill a hole with neat epoxy, let it sit a while, and then suck it back out with a syringe, thicken it, and refill the hole. I'm sure that's overkill, but then I've re-cored a few boats, and it's a horrible job, so I may tend to overkill on cored things.

I still think that it's a good idea to have at least a small basic arsenal of neat/fillers, cloth, etc. if you have a fiberglass boat and plan to do any work on it, but that's just me. There are things that 610 won't do, and the basic arsenal will. Maybe I was a bit too harsh on the repair kits (although I do like the refill ketchup packets of epoxy and hardener), but if I have a fixed-location shop, I like to have slightly more on hand (I tend to go through the gloves at a rate of knots). If you ever do any glassing then some cloth and a couple of other fillers such as microballons can be handy (for fairing). No need for them just for simple holes though.

On the Dremeling: The three bits I've found most handy are the skinny sanding drum (for digging out holes; skinny because it will fit in through a small hole), the 115 bit (great for digging out holes), the bit that is just a straight/thin metal shank with a scored pattern on the end sort of like a small drill bit (that will carve through fiberglass like butter), and one of the tapered "eraser" type bits for tidying up the edges of slightly bigger things like when I did the bilge sump. I also keep one old cordless drill on hand that just has a chamfering bit in it (it had a super annoying hard to use chuck, so I just gave up and it's now the permanent chamfering-bit drill). It's almost always good to chamfer holes in fiberglass.

Sunbeam

[Sunbeam]

[Rob & Karen]

Sunbeam,

What sort of respirator would you recommend? I am assuming that you are talking about more than a mask. Thanks.

Rob

[Sunbeam]