Epoxy on canvas experiment

[Mihun09]

Normally, we use the more modern type of traditional filler for filling the canvas on our project boats, but it takes about 6 weeks to cure in moderate temperatures, more in our colder climate. Many others have been experimenting with other sealers to improve the fill time to as little as a weekend. Some have used drywall compound, others basement sealer amongst other odd combinations. Epoxy would seem easier, but there is the brittleness that goes with it.

We are trying anyway. I made up a slurry of West System and the West #410 fairing filler and squeegeed it on a piece of raw 10 oz canvas stapled to a piece of bare plywood.

The right side is one coat with clear hardener, the left side is a second coat with the fast hardener, which is a darker colour.

After 5 days of cure on the one layer side, I smacked it hard with a pointy piece of brick to simulate a pointy rock hit. I hit it about as hard as I could and did pierce the canvas in two places, but if you hit a rock that hard when canoeing, chances are you would hole traditional filler too.

Next was to fold it and yes, if you fold it tight the epoxy cracks, but once canvas is stretched on a canoe, it shouldn't have that issue. The one coat also sanded down really nice.

Next was the wet test. It did Not stick to the plywood at all, and we could see it did not penetrate the canvas all the way, so we let a piece sit in a bucket of water all day and it did indeed suck up water to the point of curling up. When it dries we will see if the epoxy delaminated at all, but I doubt it.

Tomorrow I will try the two coat side after it has had equal curing time. So far it looks like we will try this on the Bastien after we finish the present boat project.

 

[Robin]

I have used Gluvit epoxy over at Schuyler Thomson's shop. He moves so many canoes through there, 3 coats on a canoe are done and dry in 7 days. He couldn't meet the demand if he had to wait 40 days for traditional filler to dry. He has used Gluvit exclusively for as long as I have known him.

Good luck with your experiment.

 

[Mihun09]

Robin, we can get Gluvit here but it is exceedingly expensive. We also figure this is similiar except perhaps in the high gloss we get from the West epoxy. We shall see what the two coat part works like, although we know it will be brittle, we do need to wait the month until full cure to see how that goes.

 

[Mihun09]

No Title

The two coat part was better in some ways but not in flexibility. It didn't take much bending to snap it clean to the canvas, although on the hull it shouldn't ever bend like that, but it could fracture more easily with hull flexing. Abrasion resistance is better, only one very hard pointy hit cut through the canvas and it sands out really smooth. Maybe two coats with less thickness would be the better idea, but we will find out.

Gluvit is $201 a gallon cdn plus shipping from Ontario.

 

[Canotrouge]

Have you contacted West System to ask them some questions? They are super helpful, and I'm sure they could help you find the best combination of product for what you need!

 

[Mihun09]

Have you contacted West System to ask them some questions? They are super helpful, and I'm sure they could help you find the best combination of product for what you need!

Good idea. I sent an e-mail and included this thread addy, will let you all know what transpires.

 

[Iskweo]

Regardless of what we choose to go with, my Huron is going to be the test bed for it. I am not particularly careful with my boats so if it survives a couple of seasons in my hands it has to be a winner. I could simply go with waterproof canvas and just paint over it, somewhat like veralite.

 

[Mihun09]

West got back to me and suggested using G-Flex on the canvas. They said it Would bond with the wood if it penetrated the canvas but should give the desired results. However, our best price from Noah's would be $135 for a two quart kit plus taxes and shipping, not knowing how much we would need. So, I'ma gonna try a resin and silica flour sample and if that doesn't work either, we will stick with traditional filler.

 

[Canotrouge]

I've heard of people using many coats of latex paint in place of the filler and enamel paint finish! I guess you would need lots of coats!!

 

[wysedav]

I don't know anything about canvas filler but two possibilities are Corey's Goop from the skin boat school. He makes a flexible epoxy for skin on frame kayaks. Another option is to add excess solvent to standard epoxy. When it hardens it ends up rubbery. I think around 10% or so will work.

 

[Canotrouge]

I don't know anything about canvas filler but two possibilities are Corey's Goop from the skin boat school. He makes a flexible epoxy for skin on frame kayaks. Another option is to add excess solvent to standard epoxy. When it hardens it ends up rubbery. I think around 10% or so will work.

Interesting!!

 

[Alan Gage]

I don't know anything about canvas filler but two possibilities are Corey's Goop from the skin boat school. He makes a flexible epoxy for skin on frame kayaks.

I've got some of that. Bought it quite a few years ago and have never used it. Don't know if it's still any good or not. If you're interested I could send it up to you.

Alan

 

[Muskrat]

I have some of Corey's goop too. Haven't used it yet. It is a two part polyurethane. There's also Gaco Western UA-7090. I don't think those would be the best bet though as they are made to stretch ~300% before breaking. That is great for nylon but too much for canvas. Harder polyurethanes and epoxies are available with less flexibility. You might check out Smooth-On. They have a big variety and list all their shore hardness specs. I've looked into this a lot, probably way too much. G-flex is by far the best coating for this application. It has just the right amount of stretch and more shore hardness than any other option. Unfortunately it's expensive unless you buy two gallons or more.

Here's a rabbit hole to go down. Potassium titanate whiskers. I've found a lot of white papers on using it as an epoxy filler to increase abrasion resistance and it also makes the epoxy more flexible. Unfortunately, the only supplier I've found that will sell me less than a ton wants $135 per lb. Also, I need to brush up on my Cantonese before ordering.

 

[Iskweo]

It is hard to beat traditional filler. We are always pondering ways to subsitute but it always comes back to flexability, durability vs cure time. The cure time is really what we are trying to get around here. Traditional filler is actually quite cost effective and very durable.

Since the boat restoring hobby is being wound down, this is mostly academic. We will continue to use traditional in the restorations currently ongoing and can experiment with epoxies on my test boat. Of course the issue with epoxy is maintenance of the UV protection. We have all seen examples of poorly done or neglected epoxy boats. I like the tinted epoxy on karins last build. That may be an idea as well. Canoes for the masses...made solid and with ribs/varnish interior. Looks and durability. Longevity may suffer but in today's disposable world nobody really cares about that. As long as it outlasts us, the warranty is good....lol.

And really I love tradition....its so traditional.

Christy

 

[Mihun09]

Presently we have about 3-4 years of project boats for ourselves, I figure the Morris may take me a year to restore. After the Langford we have in the shop now there is the Peterborough to finish and an old 14 foot Huron, then the Penobscot before the Morris again. I still need to get my solo in for repaint and striping this year as well.

I see a going out of business sale in the near future for us.

Karin

 

[Fitz]

As I mentioned before, we used talc for a filler for sand-ability. We applied the thickened epoxy with a squeegee, trying to avoid leaving ridges. The talc allows you to sand the cured epoxy smooth. Silica will be much more difficult to sand. For UV protection, you will need to paint it, like other filled/canvas canoes.

The canoe we used this technique on was a 20 foot Old Town Guide. A few years after we did this, the owner passed away and the canoe sat outside, possibly under a tarp (I can't recall). I recently gave it a new coat of paint and varnish and I remember being impressed with how well the canvas held up despite temperature and humidity extremes etc. and poor storage. I am thinking that this canvas job is at least 12 years old now and still going strong despite the poor storage. I have heard that some builders of grand lakers in Maine use this filler.

 

[Mihun09]

So I picked up some talc (baby powder) on Thursday but thankfully I read the container first since some baby powder is now corn starch. I'll try a batch this weekend as it is finally warming up towards canvas time.

 

[Mihun09]

It is going to take a lot of baby powder to do a hull, difficult to mix in as well, must go slow and be careful with it being so light and fluffy, but at least is smells better than epoxy, ha ha.

 

[Fitz]

Talc warrants a dust mask too. It is a mineral that is not good for your lungs. Let us know how you make out.

 

[Mihun09]

You know Fitz, you have a class action lawsuit in the works there... baby powder, talc and perfume, has been used by billions of mothers for decades without any type of warnings on the bottles about inhalation risks.

Having smoked for 40 years and all the different thinners I used to work with, I doubt talc is going to do much damage at this point to me.