Boat Builder Central - Builder Forums

Get more mileage from your epoxy!

Most builders, especially first timers, use much more epoxy than necessary. When calculating the quantity of epoxy in a Bill of Material (BOM) we include the amount needed to coat the wood, wet out the glass, make glue, fillets, and fairing paste. We then we add 15% waste factor.

The leading culprits for epoxy waste are:

1) Excessive fillet size. Follow your plans when its comes to fillet size. In almost every case first time builders make their fillets twice as large as needed.
2) Coating wood using brushes. Using a tight foam roller, you can get multiple thin and even coats of epoxy on your plywood. This method uses less epoxy overall verses sloping on one or two heavy coats with a chip brush. Brushing on heavy coats will result in excess build up in some area, and not enough in others.
3) Mixing too much at a time. Try to use all the epoxy you mix. Keep a mental note of any small areas which need epoxy so you do not leave excess in your cup. For example; if you mix up a batch of epoxy to coat your wood, and there is some left over, mix in some wood flour and make glue for butt blocks.
4) Wetting out fiberglass. A good laminator can achieve a glass/resin of 50/50 by weight. We do not assume everyone will be able to get this ratio the first time, however we do assume you will get close. Once the glass is wet and air is removed (using rollers and/or squeegees) any additional epoxy does not add to strength, quite the opposite. Use a slurry of epoxy and fillers to fill the weave of the glass as opposed to using straight (expensive epoxy)

Sounds like good advice coming from a man who's wasted a fair amount of epoxy in his time!

So, excuse me if I sound dumb but, here's the scenario. You've got say hmmm? 10' of fillet to make & tape. Ideally you want to work wet on wet right? So step 1 would be to coat the ply with a thin layer of epoxy, step 2 make the fillet from the epoxy filler you just mixed up, step 3 lay in the biax tape and wet it out. Is that how it would go? Is 10' of fillet & tape manageable in the normal working time for a single batch of epoxy & filler, or would you prepare the coating epoxy, filler and taping epoxy in separate batches? Can you mix up the filler in advance and keep it in the fridge? Could you do say 20' or 30' of fillet in one session or would that be too much?

I suppose as you get some experience with the materials you'll be able to do more and more in a single session. I'm thinking the early filleting sessions will prove a little more expensive with a few more wasted materials but sometimes that's the price you pay for experience.

Rick

Pot life is the limit here. The larger the batch of epoxy the more likely it will pop off. I would not try to store mixed epoxy. Your mix it you use it. Outside temp and the temp of your epoxy and the speed of your hardener are all important variables in the amount of time you have to work. Just mixing a large quantity of wood flour takes a significant amount of time. I don't think that you will be getting into the 10 ` plus range without help.

Wet on wet is of course somewhat subjective. Everything should be tacky and pliable but not wet. You need to let things setup a bit. Thus you tend to pre-coat around 10' of seam with one batch, fillet with the next batch, layout tape with the next batch.

A second to what's written above. A high humidity and temp. area like I live in is a big factor in mixing up epoxy batches. My epoxy has an average pot life of 10-15 minutes in the summer - with a SLOW hardner. But I quickly learned a long time ago, if the surface area of the pot is larger, you can significantly extend the pot life. I sometimes use (especially in summer times) a cheap 99 cent plastic paint tray liner. Large surface area, and after left over epoxy cures, if snaps right out and I use the tray again. As for the wet on wet, i've tried it and screw up way too many times for whatever reason - glass gets crooked, gets tacky too son. wet epoxy on dry glass is best. Just my two cents.

Thanks for the tips fella's. I'll try all the things you've suggested. I'm still a little concerned about doing very large areas such as the hull of the TW28. Even doing 1 large panel at a time it can be as much as 10 square yards. That's a heck of a lot of epoxy to mix and wet out 1708 at one time. Anywho, I gotta get a few smaller projects under my belt before I start worrying about that I guess.

Rick

If you are going to be doing a TW project. you may as well realize that in many spots its going to be a multi-person project.

When you work on a big panel one person mixes while the other works the panel.

Hey Chrisobee

Yer right. I figure if I offer 'nuff beer & pizza (w/back bacon) on here a whole bunch o' you guys will show up for those major milestones! *lol*

Mini-workshop is almost done. Should start a small project next summer. Thinking of the V10 will make a nice tender for the TW28!

Rick

Knottybuoyz wrote:Thanks for the tips fella's. I'll try all the things you've suggested. I'm still a little concerned about doing very large areas such as the hull of the TW28. Even doing 1 large panel at a time it can be as much as 10 square yards. That's a heck of a lot of epoxy to mix and wet out 1708 at one time. Anywho, I gotta get a few smaller projects under my belt before I start worrying about that I guess.

Rick

Don't forget also that epoxy goes off much, much faster in the pot than when spread out over a large area.

Several people working together has worked best for me. If you have help that understands the method and wants to work as a team it becomes a very efficient process. Start with the glass tape cut to manageable lengths and make a plastic covered tray out of plywood with 3/4" sides. It should be about a foot or more wide and at least 4' long. This is where the FG tape will be wet out with a squeegee. While one does this another puts a "primer" coat on the wood. The third mixes some of the epoxy up with wood flour/fumed silica and starts the fillets using the same tray and broad knife a drywall finisher uses. The wet out tapes are placed and squeegeed down with the excess spread out on the floor and sides. Other tasks are the same . One does a task and the others work with him to get the job done. There is little time for epoxy to set up prematurely. My D 15 was built this way in a few hours one weekend.

Robertk

It was a few hours i.e. about 5 on Saturday and 5 on Sunday. That was for the bare hull only.

Robertk

Another thing possibility is to get up real early (well before dawn the summer) and do your layups then. The coolmorning is good for longer pot life and the hot day will cure things enough so that you might even be able to sand before going to bed.

Then there's the usual tips about refrigerating your hardener, etc.

Laszlo

Do you want to lay fillets on wet precoat? I thought I wanted the precoat to set at least to the tacky stage, since its purpose in life is to prevent the resin from your putty from running into the wood and leaving too dry a fillet... I guess then fiberglassing the fillet you'd want to do before the fillet sets to tack stage, so you can shape it while glassing. Or do you want to shape the fillet with a popscicle stick/ tongue depressor/ plastic spoon, then let it cure partially so you can squeeze resin out of the fiberglass without denting the fillet? I guess I had understood wet-on-wet to mean not letting each part fully cure overnight, so the new layer bonds to the previous one, but letting each layer cure to tacky (about a half-hour?) before continuing...

Also, by 10' are we talking about 10 feet, or do we mean 10 yards? The plans for the Cheap Canoe suggest you should be able to lay all the fillets in about 5 minutes, and that'll be 14 feet for each side and another one at the bow and stern, so about 30 feet or 10 yards... So it sounds like that should be do-able in one swoop?

Good suggestions all. Now I have a question.
Has anyone noticed whether the mixture sets up any faster when applied from a caulking tube? This of course puts the material under a lot more compression than just the pastry bag method. I found these at West Marine and they work great but I still do not have a lot of experience with them.
Mark

I'm a big fan of the caulking tube. When doing the taping I mix a batch of epoxy for the precoat (medium hardener in my climate) and apply. Then a 10 oz batch of fillet (1/2 medium, 1/2 slow) to fill the tube. I can apply the fillet very fast and accurate with the tube. Then I smooth the fillet with a curved plastic scraper. Let this set for a bit while I take a break. When the fillet has just started to firm (kick) I lay the glass and wet it out.

Paul

I did a 10'2 surfboard with 12oz glass on the bottom. Now here's the kicker Mix it up and QUICKLY pour it over the surface and start working. I tried to leave enough to laminate the 10' board in the pot and slowly work it in....BAD idea...I damn near had 3rd degree burns on my hands. However a week later I saw a guy mix up as much or more epoxy and pour it on the board the sqeegie it out and wrap the rails.

When I was building surfboards this stuff was about as good as you could get. Greg Loher or something owned the company and had really good tech support. Has anyone used his resin for any of the boats. I know my epoxy surfboard I can ride over just about anything, or anyone with no worries.

Boy, I am learning something new each day. This is good as I am about to do stringers for the first time.

Questions:

1. Based on the previous posts, the filleting is done after rolling out a coating of epoxy to the stringer. Is this always the case? I saw a cutaway stringer template and was amazed that the filleting was basically a 1/4" cove. A popsicle stick should work well. How do I get caulking tubes to do this with?

2. When I bed the stringers,

a. What do I use to space it 1/4" off hull? How big/long? Do these spacers come out after the glue is set, and then filled in?

b. When I put glue (or whatever it's called...I'm a newb) in the stringer/hull gap if anything seeps out the sides do I scrape it off?

Also, I have a can of fiberglass "bondo." Can this be used for filleting? I've used it to patch a small hole on my upper hull (more of a large chip) and will probably have no use for the rest of the can.


Thanks a lot.

Pake

Pake,

I will post these questions in a new thread in the repair section - its sort of a derail of this topic

Joel

Joel, the guys at the Sherwin Williams store said that marine epoxy will "melt" or shred foam rollers. Is this true, or do I need a special foam roller? I am using SilverTip epoxy (from you).

Thanks.

Use the west system rollers from this site or buy them from a local west marine store. They are less than 1/2 price bought in 12's from here. The main tip is don't keep rolling after the epoxy starts to kick. If you get bubbles tip with a brush, once again before it kicks. Tipping after it kicks works, you just won't get as smooth a finish. In higher temperature work areas refrigerating the epoxy jugs before mixing will give you a little more working time.

I'm new to the site, as well as new to using epoxy vs traditional polyester resin and I'm a little confused by the differences in the epoxy brands. It appears that the marinepoxy brand is the cheapest, is there any real difference between that and the west system brand epoxy ? I'm planning to build a canoe, then work my way up, but I want to make sure I buy the right epoxy and not purchase a more expensive brand for no real reason. I appreciate the information.

Go with the marinepoxy. There are some slight differences with Silvertip being top of the line, but not enough difference to matter on a simple boat project. If you're building a carbon fiber mast or something exotic like that then you'll find the slight benefit to silvertip worth the cost, otherwise there have been many many boats built on here with plain old marinepoxy

Thanks for the quick reply, I figured since its being sold on here, then it must be good to use. I'm looking forward to getting started on some projects and seeing what kind of aqua art I can create.

I wasted some making glue for scarf joint on D S 15, but I used small batches for
Tape and got a feel for how far it goes. Wasted about quarter inch bottom of a cup before I learned about extensions on pumps. duhhh rookie. but that's about it. Tried to use left over at bottom of cups for various parts and sole . Did not end up with much. Wasted some of that as I used a brush. Now I know about that. Saw some cheap rollersnatnHarbor Freight.
Paint? What's best?

A few things I always do to save resin is either weigh the cloth and mix an equal amount of resin.

Or if I’m using cloth with easy math. Like a 1/2 Yard or 1 Yard then just look at the OZ rating of the cloth. An example would be 1 Yard of 8.8 oz E glass. That means for one Yard you’ll need 8.8 ounces of resin to wet that yard out. This doesn’t work for chopped stand mat.

As far as increasing pot life you can use those cheap cookie tins to spread the epoxy out over a larger surface. The deeper your pot the faster the kick.

jlangleyrn wrote: ↑Fri Jun 08, 2012 3:14 pm I'm new to the site, as well as new to using epoxy vs traditional polyester resin and I'm a little confused by the differences in the epoxy brands. It appears that the marinepoxy brand is the cheapest, is there any real difference between that and the west system brand epoxy ? I'm planning to build a canoe, then work my way up, but I want to make sure I buy the right epoxy and not purchase a more expensive brand for no real reason. I appreciate the information.

When I look at epoxy it’s like this:

Good (compared to poly)
Epon Brand: this is every composite stores generic decades old formula rebadged brand. Great example is US Composites generic brand.

Best (compared to anything)
Low VOC, high solids, epoxy: Safer, expensive, awesome performance for resin infusion and vacuum bagging. Save your money otherwise.

Welcome to our Builders Forum!! You will find good help and support from some really experienced Boat Builders!! Regarding our brand, MarinEpoxy, it is a good marine use epoxy and actually made locally. It is the most reasonable priced epoxy that we offer. Our top of the line epoxy is SystemThree (S3) Silver Tip. It is great and we strongly recommend S3 when working with Corecell, Divinycell Cell or other foams or composite material. And yes, we do sell West as this is another premium brand. I think for your start of a canoe, try our MarinEpoxy. I am confident you will enjoy using it with your first build!! Jeff

Almost done with my FS18 build. Used the Marinepoxy sold by the company. It works great! I started with pumps but just decided to use the epoxy mixing cups they sell on the supply site. They have all the graduated numbers you would need to measure the epoxy to hardener. pumps can be unreliable.

Now that I nearly finished my boat I stumbled across this thread and as I started reading I wondered what Rick is talking about having shown me a perfect video of applying epoxy I realized I am reading in the Year 2006. It is nevertheless excellent reading for all of us and definitely will help future builders. I gained again a few good tips.

I was using the epoxy to seal my carport cement floor as it dripped off of the hull.. No waste there!

I know this is an old thread, but noone mentioned resin first. Resin first saves me some as well.

If I pour hardener first and run an extra ounce; then I need to double the resin.

If I run the resin heavy, I dump it into a catch. The resin doesn't dry up like the hardener, so when I pour resin, I can adjust an overpour easier than an overpour of hardener.

Then if I run 8oz resin (and adjust), I add 4 oz hardener.

Much easier than running 4 or 4.5 oz hardener and adding 9 oz resin.

The other thing is as a system, doing it the same seems good.

Guys, good thread for our newer builders!! I had not seen it prior to this morning!! Very good reading!! Jeff

Really good tip Fallguy has put out there a few times is, after mixing pour into bigger containers to spread it out more. If you have 10 minute pot life then to get those 10 minutes it can't stay in a little mixing cup. Epoxy gets warm when it starts to cure. In a little cup it's own heat will cause it to turn even faster. This really helps when using fillers. Once you mix everything you pour it into something else you can see if it was mixed good or not. spreading it out on a large flat surface extends the pot life and you can make sure it is mixed well because it is very easy to keep mixing it as you use it. If you mix with one tool but spread with another, keep the mixing tool on the spreading tray so you can use it to scrap your spreading tool.

Keep cut pieces of cardboard in little stacks to clean off the spreader tray when done. You can get 8" trays (for neat epoxy) in the dollar stores 3 for a dollar. After use just let the epoxy cure that is left in it and it will pop right out by flexing it and compressed air, another tip from Fallguy.

At the beginning of the thread it mentioned using left over epoxy mix to fill holes and places that need just a little. If you are old like me and forget a lot of stuff put painter's tape on those spots. When you see you have extra just look for the tape and pull the tape off as you go.

If you cover a scrap of cardboard with packing tape you can use it as a tray for thickened epoxy. Cheap and home made, that idea was featured in one of Boat Builder Central's videos.

I just use a cutting board, easy to clean.

Dang that is a great idea Topwater. You been holding out on us