Epoxy question.

Ed L.

Ed L.

Well-known member
Supporter
Life has gotten in the way of working on my boat floor but I finally got the floor glued and nailed in over the weekend. I'm going to lay a 4" tape around the perimeter gluing the new to the old and then cover the whole floor with fiberglass. My question is do you guys mix epoxy and start brushing on the tape our do you use anything to thicken such as cabasol? What are the pros and cons of using cabasol if any?
 
Ed,

You do NOT want thickened epoxy when you are wetting out your glass cloth or tape. Use unthickened only and in this heat you better work fast or mix in small batches. If you need to gap file around your floor use epoxy thickened with wood flour before you put your tape down. Cabosil gives a nice finish if you need to fare the surface of imperfections or gap file in a visible place. The one difficulty is that it sands down harder than wood flour filler - more effort. Cabosil does mix well with epoxy and forms a nice homogeneous material.
 
The thin epoxy will run out, if you attempt to put too much on in one coat. I know from experience. That is where multiple coats come in, if more is needed.
 
I just raised my transom on my boat to accommodate a long shaft. As mentioned do not used thickened epoxy to wet out the glass. I did 2 layers of glass and then thickened some epoxy to fill in the weave and make it smooth. I needed to thicken the epoxy so it wouldn't run becasue it was on a vertical surface. I just used a chip brush to wet it out and then a rubber squeegee to get out the excess resin. I plan on posting up pics when I get it complete but I have no action shots. Once the epoxy is mixed its go go go.
 
I put 6in tape around the feather edge on my sneakbox. The problem I had was the tape sliding around while trying wet out the tape with a chip brush. I ended up using a old sheet of plywood and laying out the tape on the ply and prewetting it out. Then with the help of a friend picking up the wetted out tape and placing it on the boat. Then going over with more epoxy as needed. Good luck.
 
Never thicken your resin you will be wetting glass out with. Be careful where you use cabosil,(cabosil is great, it is super tough, used for structural bonds, not fairing), because the cabosil will be harder than the wood surrounding it. When you sand the cabosil you will end up removing more wood from around the cabosil than you do the cabosil, creating a pimple looking area. As suggested earlier use wood flour or a product called micro-balloons aka microlight. Also be aware that the wood will soak up a bunch of your resin. If you don't use enough resin the wood will suck it right out of your cloth and the cloth will not be wet out properly. You should roll resin onto the bare wood before you lay your glass on it to ensure the wood is properly saturated. You should also paint some resin onto areas you intend to use resin mixed with any filler, especially exposed ends of plywood. The wood will soak the resin right out of the filler and leave you with a poor bond. Exposed edges of plywood really soak up a bunch of resin. Use slow hardener. Or if it is really hot you may want to try some super slow hardener.

Also, if you plan on painting the whole boat with epoxy you may want to consider cutting your epoxy with zylen. I may have misspelled that. I had never heard of this before until last week. A fellow I know is building a boat out of cedar planks. He showed it to me and told me he had painted the entire boat inside and out with West Systems epoxy thinned with Zylen. I have been messing with fiberglass for a long time and have never heard of this. The guy that told him to do it was also there. He was an old scraggley dude that new how to build boats. We talked boats awhile and he told me he and a bunch of other people had been thinning epoxy for years with great success. What he said made sense. The zylen thins the epoxy which allows it to penetrate deeper into the wood grain. It also makes your epoxy go a whole lot further. I examined his boat and it damn sure seemed to be epoxied up pretty well. I'm going to give this a try next time I build a boat. I would love to here what anyone else has to say about this.

Good luck with your new floor.
 
Thanks for all the input. Here is the boat I'm working on.

Pete, it is hot but the garage is air conditioned and the US Composites epoxy I bought is the 635 slow hardener mix. The stuff is great with good pot life.

DSCN2609.jpg


I probably did it all wrong when I used wood puddy to fill the gaps and build up some areas where the old floor level and the new didn't quit match up. Oh well, I'll know better when I have to fix it.

Chris your way of wetting out the tape first makes sense if I only had some help. I had decided how I was going to handle the possibilty of the shifting tape was to brush epoxy out on the floor first then apply the tape and more epoxy over the tape once it's in place.
 
Ed,

I have found that a small foam roller works the best for wetting out cloth or tape. Here it is:
007-1.jpg
I bought mine at Menards I think but most paint departments have them. They don't lift or move the tape around when putting on epoxy. Get the extra pack of roller covers and you can do multiple coats.
 
I read this in some West System hand out some years ago. Do not use zylene to "cut" epoxy. Research it out. Zylene evaporates while epoxy cures through a chemical reaction. What happens is that the zylene will create channels or veins in the cured epoxy after it evaporates. This will compromise the waterproof properties.
 
Thank you for responding with this info. I appreciate it. I was skeptical when he told me about the Zylene but it sure did seem to have worked on his boat. Also, the guy that told my friend to do it said he had built a bunch of boats using this method. He said he had a couple that were 20 plus years old that were still going strong. Granted they were kayaks he was talking about. I'm still skeptical, but I wonder if the West Systems folks might be distorting or overstating the effects of the Zylene because they don't want people using less of their product? Just a thought.

I'll do a little more research into this.
 
Hey Ed another way you could prewet the tape by yourself is wet the tape on the plywood then roll it up get in the boat get it lined up and unroll down the seem. If you are using slow cure you have plenty of time to do this. I used med cure last summer and felt like I was waiting for it to tackup so I could do more coats of epoxy. I think this is your best bet.
 
Ed, I would also use some sand paper and rough up the fiberglass part of the floor where the epoxy will stick. The epoxy will adhear better that way. Also paint epoxy around the edge of the plywood floor where the tape will go. As others said the wood can suck the epoxy out of your cloth tape.
 
John:
Well, if that's good enough for you then I say go for it. Personally, if I was going to spend that much time on a boat, I would follow the directions. It the great scheme of things, how much are you really going to save?

As a further explanation, epoxy is 100% solids, it combines and starts the chemical process and solidifies, you lose nothing to evaporation. Now introduce Zylene or any number of "thinners", this is suspended within the epoxy and when it evaporates it will create voids within the cured epoxy.

Good luck!
 
This discussion re: the use of sovents to thin epoxy is interesting. I have done this on several occasions to facilitate penetration of the wood, using denature alcohol. This was suggested by a professional boat builder. I believe this is the premise of CPES? I have always done this on base coats, again to soak in. I am confident the solvent was long gone before the epoxy crosslinked in my case. Any overcoats have been non-thinned. Can someone point us to a link showing us this void occurrence? I would be interested to learn more about it.
 
Pete....your right, Menards is the place close to work. I spent my thirty bucks on more goodies at lunch time.

Chris...that's how I wetted out the tape I put over the boo boos in the hull I made. Rolling it up and then rolling it out works great for putting glass on over head.....

AND whoever mentioned putting packing tape over your wetted glass to get a smooth surface while it cures. Now that's the cats meoww!! After a couple of days curing you just pull the tape off. Easy peasy as one old timer would tell you! Of course I'm not very good at it yet and have a couple of folds in the tape but you can't see it unless you know where to look. I'll know what I'm doing next time.
 
I've never tried thinning epoxy, but I do know we use exylene (zylene) here at work and it is considered one seriously dangerous chemical due to its extremely low flash point. The amount of air handler equipment we had to install to carry away the fumes was quite expensive. Kind of broke me of the desire to be around it....

John
 
Terry,

I can see what you mean about why voids would occur. However, in my mind I see the xylene(or however its spelled) mixing with the epoxy on a molecular level. Spacing the epoxy molecules further apart from each other in a consistent manner, then evaporating away. If the two substances were mixed properly I would think this would be the case as opposed to large areas being saturated with epoxy, and having large gaps between them. So yes, indeed there would be gaps between the molecules but they would be consistent and occur on such a small scale that the finished product would be well saturated in a practical sense.

I would like to point out that I'm not convinced by the above argument that I just made. I'm playing the devils advocate in pursuit of figuring this situation out. I'm still skeptical of this thinning business.

As far as saving money by thinning epoxy. Well that's what really got my attention. The boat my friend has built is 19' long, about 6 or 7' wide, with lots of freeboard. It's a displacement hull with a cute little cabin on it. He claims he used 4 gallons of epoxy to paint this whole boat. That is crazy. Maybe he was drunk when he told me this and really didn't feel like letting the facts out, but that is some real savings. The wood really does look totally saturated with epoxy. I feel like that means something. If it was dry wood I could see it right?

I built a modified duckhunter II (by gator boats). I glassed it inside and out, totally covered. The boat is a little over 15' and 4' wide. I used 10 gallons of epoxy. Now I really laid a serious glassing on this boat. I wasn't messing around. I over built the thing. And think it was a great idea still--4 years ago. But my friends' boat dwarfs my duckboat. The idea of using such a small amount of epoxy intrigues me a great deal. If I could get away with this it would open up a whole new world of inexpensive boat building projects. The only reason I don't build boats constantly is that I can't afford it. If I could build a boat with only a couple gallons of epoxy I would adjust my techniques accordingly, (use heavy wood/no glass ect..) and build them all the time. I love it. I also dumped 4 gallons of epoxy onto a layout boat a couple years ago as well. My layout boat had twice the epoxy my friends "real" boat did. So you can see this is a serious matter.
 
Here is an article concerning all of the ins and outs of thinning West System epoxy.

http://www.epoxyworks.com/14/index14.html
 
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