8 oz. Dacron Leaking

[Tumblehome88]

Hi Kudzu (and others),

    The 8 oz. Dacron I bought from you and used on my Geodesic Aerolite Arrow 14 canoe has developed leaks after only three paddles, the longest being 16 mi.  Water oozes in like beads of sweat on most areas that I can see.  This in spite of 5 coats of Zar exterior polyurethane.

 

Is the best solution to paint over w/ an oil-based paint, or is there a more fundamental problem, meaning start over?

 

Thanks!

 

P. S. Just joined forum, subscribe to MAIB and have built 11 boats, 5 kayaks, 5 canoes, 1 sailboat, live in NH.

[woodman]

How are you applying the finish? I just bought some from him too....

I brush mine on, 3 coats of Helmamans spar urethane..... 

[kayak278]

I second the Helmsman Spar Urethane....used 3 coats on my first SOF several years back on 8oz poly.  Worked great.  I applied it using a foam brush.

[Kudzu]

Water oozes in like beads of sweat on most areas that I can see. This in spite of 5 coats of Zar exterior polyurethane.

Without seeing it in person I can only hazard a guess, but this is an educated guess. My guess is "You need more sealer on the fabric and you have unsealed pin holes in the fabric." Sweating it a perfect description of boat that is not totally sealed. When I first started using this fabric I had a similar experience using paint as a sealer. After a little experimenting I discovered that with the boat upside down on sawhorses, in the sunlight. If I put my head in the cockpit I could see LOTS of tiny pinholes of light in the bottom of the boat. Additional coats of paint solved the leaking. With your translucent coating I don't think it would be dark enough inside the upside boat to see them, but I it sounds just like what I had happen. And it is the only reason I can see that it would leak and look like sweat. As some of the other have implied, 5 coats doesn't really mean much. It depends on heavy the coats where, my 3 coats might be as heavy as you 5 coats. It might take you double that if you put it on really thin. I could be totally wrong, but I am betting you just don't have enough finish on it and you have a lot of tiny, tiny pin holes that are seeping. PS One more thing. The 8 oz fabric is a much looser weave than the aircraft dacron's are. So this will take more finish to seal. My new 11.5 oz is a very tight weave and I believe one heavy coat properly applied would seal that fabric because of the tight weave. Each fabric is a little different.

[mitchmellow]

I put a CFL bulb (to reduce the heat) in an old trouble light, duct taped the trouble light to about a 4 foot stick, waited till dark, kept the lights off in the garage, put the trouble light inside the overturned kayak and looked for pinholes ( 8 oz. recycled poly) as I moved the trouble light up and down the length of the boat.  It was the only way I could finally find them.  Worked great and it hasn't leaked a drop since.

[Tumblehome88]

Thanks for all the replies.

 

I feel a little silly because I went to a lot of trouble to find the Zar polyurethane when the Minwax Helmsman Spar Varnish is available 15 min. away.  I'm thinking that there is some problem w/ the Zar filling the loose weave on the 8 oz. Dacron.  I plan to get some Helmsman Spar Varnish today, apply w/ a foam brush (what I used before), and use the light-on-a-stick to check for pin holes.  If I still have a sweaty inside, I'll try painting.  It turns out that you cannot buy oil-based paint in NH so I'll have to go w/ a latex.  

 

I'll post the results of this later.

[kayak278]

I put a CFL bulb (to reduce the heat) in an old trouble light, duct taped the trouble light to about a 4 foot stick, waited till dark, kept the lights off in the garage, put the trouble light inside the overturned kayak and looked for pinholes ( 8 oz. recycled poly) as I moved the trouble light up and down the length of the boat.  It was the only way I could finally find them.  Worked great and it hasn't leaked a drop since.

 

That is a great technique, one I use as well....funny story:  I'm an early riser, so at 4:30am one morning I put on a headlamp on my front porch and proceeded to check for pinholes on my North Alaska Retrieval SOF,  I guess it looked a little shady because my neighbor thought I was a burglar and came over to try to scare "the burglar" (me) off!  We both had a good laugh over it.

 

Matt

[Kudzu]

ZAR oil based is a great product and was/is a staple for nylon.  It was one of the few things that would stick to nylon. Nothing wrong with it, but the good thing about polyester is that most anything will stick to it. Helmsman will work, but it is not a great product in the UV protection area. If you store out of the sun it is fine.

 

I have used it on paddles because it was easy to get but it just doesn't last like a good marine varnish.

[P Doug (WA)]

I used ZAR on my kayak, no problem.

[woodman]

Thanks for all the replies.

 

I feel a little silly because I went to a lot of trouble to find the Zar polyurethane when the Minwax Helmsman Spar Varnish is available 15 min. away.  I'm thinking that there is some problem w/ the Zar filling the loose weave on the 8 oz. Dacron.  I plan to get some Helmsman Spar Varnish today, apply w/ a foam brush (what I used before), and use the light-on-a-stick to check for pin holes.  If I still have a sweaty inside, I'll try painting.  It turns out that you cannot buy oil-based paint in NH so I'll have to go w/ a latex.  

 

I'll post the results of this later.

I use one of my old Artist paint brushes 1 1/2'' wide stiff bristle .....

[square_nails]

Hello everyone, I am curious and was wondering about the pinholes left behind after coating the polyester fabric if it was possibly caused by surface tension from the fibers having a residue from manufacturing and if so the idea of washing the fabric beforehand allowing the sealer of choice to flow better and fill said pinholes? Just a thought.

[Tumblehome88]

I'm happy to report that things have improved.  I added two libral coats of Helmsman Spar Urethane with a foam brush, paddled upstream and upwind on a nearby river and floated down for a good 20 minutes to eliminate any paddle drippings, and saw no leaks.  When I applied the ZAR, I used a technique that CLC recommends--putting the varnish on in one direction and then going across it to eliminate any holidays.  It is possible that this made the ZAR too thin.  The Helmsman seems much thicker and I think it due to this technique rather than an inherent quality of the ZAR.  I'll  take the canoe on a longer paddle soon, but I'm confident that is now waterproof!

 

Thanks for all the comments.

[Kudzu]

The reason for the pinholes is the loose weave of the fabric. This is a VERY loose weave. So there are small pinhole gaps between the fibers and you have to apply enough paint or varnish to seal all those gaps. 

 

The new 11.5 oz is the exact opposite, very tight weave almost stiff fabric. I believe one good coat would seal this fabric.

[Hirilonde]

  It turns out that you cannot buy oil-based paint in NH so I'll have to go w/ a latex.

That's not true at all.  I found Rustoleum available in NH and it took me less than a minute using Google.

 

 

http://www.acebenfranklin.com/

http://www.acehardware.com/family/index.jsp?categoryId=12686366

[Tumblehome88]

I guess you shouldn't believe everything they tell you at HD.

[Hirilonde]

I guess you shouldn't believe everything they tell you at HD.

Home Despot in RI doesn't sell oil based paints either, but most other paint suppliers carry at least some.  I avoid HD like the plague, I despise just about everything they do as a business.

[P Doug (WA)]

It is certainly not all HDs.  Mine local one sells oil based paint.  My local one is really an exception and I hope the manager never leaves.  Great place to shop.

[Kudzu]

The manufacturers are pulling it off the market quarts first and have actually removed existing stock from one of my suppliers. Gallons should be available for a while but they too will be going away eventually.  I suspect there will always be some available if you know where to look and can afford it. There will still be need for it in some industrial and commercial applications. But it may get to the point we can't buy it.

[Hirilonde]

I think it is rather ironic that oil based paints are being restricted and 2 part LPUs are sold with an MSDS that makes is seem almost harmless.