Hello, I have been lurking around for about a year and appreciate all of the great information and experience that has been shared. I am building a Freedom 15 and have just finished stripping. I am now fairing and sanding the outside of the hull. Everything is going along well and I am very pleased with the results so far.
Here's my question: I have talked with another builder and he said that he wished he had precoated his boat with a coat of epoxy before he put the fiberglass on. His thoughts were that by sealing the wood prior to fiberglass application it would stop any over saturation, bubbling or dry areas. He felt that he would have gotten a better job of fiberglassing if he had used a sealer coat first. I know this will add cost and weight of an extra coat of epoxy, but wonder what this group thinks about precoating/sealing. I have read "Canoecraft", Susan van Leuven, Gil Gilpatrick and Randy Folsom and none of these books mention precoating or presealing. Is this really a problem?
Thanks for any ideas or suggestions.
Vann Evans
Chapel Hill, NC
precoat with epoxy?
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vann evans
- Posts: 45
- Joined: Fri Oct 17, 2008 8:52 pm
- Location: Chapel Hill, NC
Hi Vann,
I think if done correctly, a precoat will only add marginal weight. The precoat is supposed to just saturate the wood, not sit on top. This happens whether you precoat or not. If you don't precoat, you just have to be a bit more vigalent when wetting out the fiberglass. The concern is that you may wet out the cloth and move on, you may have places where the wood soaks up the epoxy from fiberglass and the fibercloth no longer has enough epoxy.
For some generalizations it seems to me that pre-coating is discussed a lot more when talking about kayak building. It also seems to me that the more experienced the boat builder, the less likely they are to pre-coat.
I built a s&g kayak and pre-coated before glassing. When I did the outside of the hull on the Freedom I'm working on now I also pre-coated. However, this evening I will be glassing the inside and don't plan to pre-coat.
Either way works!
I think if done correctly, a precoat will only add marginal weight. The precoat is supposed to just saturate the wood, not sit on top. This happens whether you precoat or not. If you don't precoat, you just have to be a bit more vigalent when wetting out the fiberglass. The concern is that you may wet out the cloth and move on, you may have places where the wood soaks up the epoxy from fiberglass and the fibercloth no longer has enough epoxy.
For some generalizations it seems to me that pre-coating is discussed a lot more when talking about kayak building. It also seems to me that the more experienced the boat builder, the less likely they are to pre-coat.
I built a s&g kayak and pre-coated before glassing. When I did the outside of the hull on the Freedom I'm working on now I also pre-coated. However, this evening I will be glassing the inside and don't plan to pre-coat.
Either way works!
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James Hanrahan
- Posts: 23
- Joined: Thu Sep 13, 2007 6:48 pm
- Location: Wiarton Ontario
Hi Vann,
I would also advise that you use a seal coat. Susan Van Leuvan mentions it on p 76 in her book as does Nick Schade in his book Building Strip- Planked Boats. As a new builder ther are many advantages to using a seal coat and unless applied in excess it shouldn't make much difference in the final weight if any.Seal coating saves you from having to watch for air bubbles forming in your subsequent coats.I agree with Sluggo and the other builder
Good luck
James
I would also advise that you use a seal coat. Susan Van Leuvan mentions it on p 76 in her book as does Nick Schade in his book Building Strip- Planked Boats. As a new builder ther are many advantages to using a seal coat and unless applied in excess it shouldn't make much difference in the final weight if any.Seal coating saves you from having to watch for air bubbles forming in your subsequent coats.I agree with Sluggo and the other builder
Good luck
James
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Tim Eastman
- Posts: 245
- Joined: Sun Oct 23, 2005 12:40 pm
- Location: Grand Rapids, Michigan, U.S.A.
I've heard both sides of the argument. One side says it adds too much extra weight - the other side says it seals the wood and helps prevent air bubbles under the fiberglass.
I precoated and I'm glad I did. The outside came out flawless (did I really just say that?) but even with a precoat on the inside I still got a couple small bubbles under the fiberglass. Reason being that we started on a cloudy day and the sun came out and blasted right through the garage window directly onto the part of the hull we were working on. I wasn't attentive to surrounding conditions. Lesson learned.
A cheap trick we learned with severe tumblehome - the precoat was still very slightly green and we sanded it only enough to take down any nubbies that would have snagged the fiberglass. Gave it a quick wipe down and laid out the fiberglass. The fiberglass laid right into the tumbelhome on the solo and stayed there during the outside wetout.
I precoated and I'm glad I did. The outside came out flawless (did I really just say that?) but even with a precoat on the inside I still got a couple small bubbles under the fiberglass. Reason being that we started on a cloudy day and the sun came out and blasted right through the garage window directly onto the part of the hull we were working on. I wasn't attentive to surrounding conditions. Lesson learned.
A cheap trick we learned with severe tumblehome - the precoat was still very slightly green and we sanded it only enough to take down any nubbies that would have snagged the fiberglass. Gave it a quick wipe down and laid out the fiberglass. The fiberglass laid right into the tumbelhome on the solo and stayed there during the outside wetout.
Tim Eastman
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Be an example worth following
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Be an example worth following
Well I tried to ignore this topic this time , but couldn't , there are two sides to every story. Bubbles are not much of a problem on the outside of the hull so if bubbles are your reason to precoat then it is a waste of time. All of the authors mentioned above all have one thing in common none of them are Ted Moores , and he will tell you not to precoat ( I asked him) I have done a lot of searching on this topic and what I am beginning to think is precoating got started by builders using a roller for wet out. You can't get enough epoxy on with a roller to saturate the wood and cloth thus starving the cloth. Go to West System's web page and you will find a lot of info on epoxy , and you will find that the prefered method for aplying cloth over wood is the dry method and if you apply the cloth over epoxy then it needs to be done while it is still wet. So both Ted Moores and West System say no to precoating , two very respected names in boat building.
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Tim Eastman
- Posts: 245
- Joined: Sun Oct 23, 2005 12:40 pm
- Location: Grand Rapids, Michigan, U.S.A.
Personal mileage will obviously vary. If you're a builder you try something based on your research and how others have successfully done it. After hearing the comments on other forums (and this one) some of us decided to precoat.willo wrote:Well I tried to ignore this topic this time , but couldn't , there are two sides to every story. Bubbles are not much of a problem on the outside of the hull so if bubbles are your reason to precoat then it is a waste of time. All of the authors mentioned above all have one thing in common none of them are Ted Moores ,
It's not wrong - it's just different from how you would do it obviously. I have not tried fiberglassing without precoating - it might actually be easier for all I know. I might just like it.
If it works it's not wrong.
Tim Eastman
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Be an example worth following
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Be an example worth following
I would suggest that you use the search feature in this site and look for epoxy problems and pre-coat. Take your time to look through the old messages and you will find messages (especially from beginners) asking for help after they had problems. You will find a common theme running through these messages and note that they typically did not precoat.
On the other hand I have yet to find a single message where someone pre-coated and regretted having done so.
Based on my searches here and on other forums I pre-coated and I can say that I don't regret having done so. Take that 2 cent opinion for what its worth. Maybe on my next boat or the one after that I will have the confidence to go without a pre-coat but then, why screw with a good thing?
On the other hand I have yet to find a single message where someone pre-coated and regretted having done so.
Based on my searches here and on other forums I pre-coated and I can say that I don't regret having done so. Take that 2 cent opinion for what its worth. Maybe on my next boat or the one after that I will have the confidence to go without a pre-coat but then, why screw with a good thing?
I did the inside of my hull last night and did not pre-coat. That is the first time that I've done it that way. I can't say that I noticed it being much different. I did see that I had to go over a few areas again while applying the epoxy, because the wood soaked up a lot of epoxy. Other than that, it was kind of the same as other times I've done it with a pre-coat.
I wouldn't get to hung up on pre-coating, trust me you will come to other aspects of fiberglassing that are much more challenging. I had a lot of difficulties getting the glass to stay down while doing the inside of the hull and barely got the cloth down before the epoxy set. It was definitely the most difficult aspect of building a canoe that I've experienced.
I wouldn't get to hung up on pre-coating, trust me you will come to other aspects of fiberglassing that are much more challenging. I had a lot of difficulties getting the glass to stay down while doing the inside of the hull and barely got the cloth down before the epoxy set. It was definitely the most difficult aspect of building a canoe that I've experienced.
I've done it both ways. Both work fine and have advantages over the other method in some circumstances. It seems to me that many of the arguments about techniques like this come about because what we are doing really is different. Different types of epoxy at different temperatures behave very differently. A low viscosity epoxy like system 3 clear coat goes on beautifully with a roller, but can drip through staple holes leaving starved areas. Precoating avoids the problem. (Steaming the staple holes closed will prevent this too.) A more viscous epoxy may offer little advantage to precoating, except that you need to get less epoxy into the cloth on wetout, so it may give you a little more time with a fast setting epoxy. Unless you really overdo the precoat, it should not make any difference to the weight of the boat. If you do precoat, you need to get the timing right to make sure it is not so tacky that it makes placing the cloth difficult -- Tim Eastman apparently got it perfect. Most of us are not in that much of a hurry, but there is no question it's faster to not precoat.
Alan
I posted earlier this year about my bubble problem i had on the inner hull and i did not pre coat.
I had a controlled environment at 72 degrees.
I had three guys total. 1 mixing. 1 applying the mix ,pouring at the bottom and squeegieing from the bottom up the sides. And 1 keeping track of time then tipping each section off with a brush in 20 minute intervals.
I used west system epoxy.
We encountered absolutely no problems everything went fine. After we were done there were no bubbles. I checked the finished product in about 2 hours and i saw several bubbles appearing only at staple holes. Most were the size of dimes others were the size of quarters. The bubbles were at the bottom, on the sides and at the sheer line. I sanded every thing down after it cured and filled the bubbles but i can see were they were now.
I dont know exactly what went wrong except that i think the epoxy filled the staple holes and starved the cloth around the holes.
I learned about not precoating and on my present build now i will start early and precoat the inner hull.Wait until the first coat is smooth to the touch then apply the cloth and 2 more coats of west system epoxy. My theory is that the precoat will fill the holes and limit the bublles that i encountered on the first build. I can live with any extra weight if there is any.
Brad
I had a controlled environment at 72 degrees.
I had three guys total. 1 mixing. 1 applying the mix ,pouring at the bottom and squeegieing from the bottom up the sides. And 1 keeping track of time then tipping each section off with a brush in 20 minute intervals.
I used west system epoxy.
We encountered absolutely no problems everything went fine. After we were done there were no bubbles. I checked the finished product in about 2 hours and i saw several bubbles appearing only at staple holes. Most were the size of dimes others were the size of quarters. The bubbles were at the bottom, on the sides and at the sheer line. I sanded every thing down after it cured and filled the bubbles but i can see were they were now.
I dont know exactly what went wrong except that i think the epoxy filled the staple holes and starved the cloth around the holes.
I learned about not precoating and on my present build now i will start early and precoat the inner hull.Wait until the first coat is smooth to the touch then apply the cloth and 2 more coats of west system epoxy. My theory is that the precoat will fill the holes and limit the bublles that i encountered on the first build. I can live with any extra weight if there is any.
Brad