Boat Building Forum

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Re: Varnish Problems
By:Paul Jacobson
Date: 5/2/1999, 9:15 pm
In Response To: Varnish Problems (Mike Hanks)

> I am having troubles with the varnish drying on my first kayak. I put the
> varnish on 5 days ago and it is still tacky. The places where it has dried
> it look scaly. If I try to sand it, the sandpaper gums up immediatly.

> I put the varnish on over System 3 Epoxy. I thoroughly sanded the kayak
> with 150 and 220 grit sandpaper after letting the epoxy cure for 3 - 5
> weeks. (some parts of the boat have cured longer than others) I cleaned
> the sanding dust with cheesecloth moistened with Interlux Brushing Liquid
> 333, then dry wiped it with cheesecloth again. The varnish is Interlux
> Schooner 96, thinned 10% with Interlux Brushing Liquid 333. I probably
> should not have thinned it, but it is too late now. It is over 70 degrees
> and quite dry in my basement.

> Pygmy recommends ZSPAR's Flagship Varnish, but I was unable to find it in
> the stores around here. The people at the local boat shop don't know much
> about putting varnish over fiberglass.

> I'm stumped as to what to do. Should I try to remove it? How? Wait for it
> to cure, sand it down and revarnish it? Should I use a different varnish?

The weather is too nice to mess with varnish problems, so I'd suggest you ignore them and just enjoy paddling the boat. Wet, dry, or in-between, the only purpose of the varnish is to provide a UV barrier. It adds nothing to the strength of the boat, or the functionality. If you don't leave your boat in the sun for days and weeks at a time, you don't really need varnish at all. Since it takes months and years for UV damage to start, you are not doing any harm by NOT varnishing for a while.

The advantages of this slothful suggestion: Getting the boat out into use may help the solvent in the varnish to evaporate, leaving you with a delayed, but hard, varnish surface. If it doesn't do that, the exposure of the unhardened varnish to the water may make it easier to remove the bad spots.

The disadvantages: The gummy scum may rub off on items you don't want to get scummy. The bad areas will look REAL bad. But, like a teenager's acne, the problem areas are VERY easily seen, and with simple treatment and a bit of time they DO go away. Until you get a nice coat of varnish on you will want to store your boat out of direct sunlight when it is not in use. (This is a good suggestion even after you have varnish on it)

Unless you own stock in a sandpaper company, sanding off gummy varnish is a nasty job. I'd try using cloth rags dampened with a solvent that would disolve the varnish. Expect to go through a lot of rags. Don't use paper towels. Nick likes to use Scotchbrite (a registered trademark of 3M) pads for a final sanding. Those might be ideal tools here, too. Get them wet with a solvent and they may have enough abrasive action to remove the gummy mess. Yes, they will get gummy, too, but you should be able to rinse them clean in a tray of solvent and then go back to removing the gummy mess on the boat. The solvent fumes may get you sick if you do not wear a proper mask, so get one. Wearing impervious gloves is mandatory. Vinyl should work. I'm not sure if latex will.

If the interlux brushing liquid works as a solvent, use it. Otherwise, try using mineral spirits (paint thinner). Cured epoxy resin is used in coating fuel tanks (gasoline and/or diesel) and is extremely resistant to petroleum distillates. If gasoline won't hurt it, naptha, kerosene and paint thinner won't hurt it either.

Once you think you have it clean, go paddling again. If you have uncovered an area with some residual amine blush, the water should wash it away. If there is some more bad varnish, it will show up. If you have residual solvent it should wash away, too.

I don't particularly agree with the general trend to rush into varnishing things. After a few launchings you WILL get some scrapes. After paddling a bit you may want to try adding additional scrape and ding protection, rudders or skegs or keels or cup holders or braces of one kind or another. These things get epoxied in, and you would have to sand off the varnish to get a good bond. If you don't varnish first you don't have to sand the varnish off two weeks later. My thought is: build and test the boat, then after a few weeks -- when the epoxy is fully hardened and all modifications are installed -- pull the boat out of the water, clean it, sand it and varnish it. Get used to this practice. Every year or two you'll have to revarnish it, and that means cleaning and resanding it (lightly) first.

My first thought on your varnish situation is that the thinner you used is not compatible with the varnish. My second thought was that the varnish is old. You might try a bit of unthinned varnish on a scrap board and see how well two or three coats set up -- and how long it takes. The first coat may just soak into the wood. The real test is whether the 2nd and 3rd coats dry properly. If they don't, take the can of varnish and the plank to your supplier and see if they will give you back your money.

There are several places on the internet that will sell you varnish by mailorder. Even my local home housewares/hardware store carries good spar varnish with a UV inhibitor. At first I used Pettit High-build varnish that I bought over the phone from Clark Craft (www.clarkcraft.com). Since then two boating supply stores have opened within driving distance of my home and I have debated using other brands. I get about 3 to 4 years of life from the Pettit, so I'm happy with it, and it comes delivered to my door. On the other hand, I can browse and read labels at the boat store. Ah, such dilemnas there are in life.

Hope these random thoughts are of some aid.

Paul Jacobson

Messages In This Thread

Varnish Problems
Mike Hanks -- 5/2/1999, 3:00 am
Re: Varnish Problems
Jay Babina -- 5/3/1999, 10:15 am
Re: Varnish Problems
Mike Hanks -- 5/7/1999, 5:25 pm
Re: Varnish Problems
Paul Jacobson -- 5/2/1999, 9:15 pm
Re: Varnish Problems
Mike Hanks -- 5/2/1999, 11:49 pm
Re: Varnish Problems
Rob Cochrane -- 5/2/1999, 5:30 am
Re: Varnish Problems
Mike Hanks -- 5/2/1999, 6:11 pm
Re: Varnish Problems
Mike Hanks -- 5/2/1999, 12:29 pm
Re: Varnish Problems
Pete Rudie -- 5/2/1999, 2:23 pm
Re: Varnish Problems
Mike Hanks -- 5/2/1999, 6:15 pm