Removing old varnish

[Stephan]

Hi!

I have a canoe that has old (possibly original) varnish that is in great shape and has that golden oldie look that I want to maintain. The problem is that at some point someone caked on some terrible shellack or varnish on top of it and it's slowly peeling off. The canoe was very recently recanvased and painted (before I bought it) and everything is beautiful except for this extra layer of stuff that's coming off the inside. I just bought it last fall and I'm planning on taking care of this little problem when we get into better spring weather.

The 'bad' varnish is slowly peeling off over time and it seems it has even pulled away a little more since I bought it. It's sort of curling up and peeling away from the old varnish. It's hard and crispy but I left it in the sun for an hour today and pulled at some of the bad stuff. When I pulled pieces off, it felt a little like taffy pulling off the canoe so I'm thinking that heat could possibly help me remove it. I don't want any kind of chemicals to remove it since I don't want to ruin the great varnish underneath.

I was thinking of maybe trying to use warm water and see if I can scrub it off with a soft brush. I was also thinking maybe a heat gun would soften it and I'd be able to brush it off. I could experiment with all kinds of ways but I thought I'd toss the question to you fine folks in case someone here has an easy and quick way to do it. I'm posting some pictures that should help you see what I'm dealing with.

Ideally, I'd like to remove the bad stuff while presevering the good stuff, sand lightly and apply a high quality varnish.

Thanks in advance!

Stephan

 

[Denis M. Kallery]

A quick check if it is shellac is to get some denatured alcohol and try it on the peeling stuff. Alcohol is the solvent for shellac and will soften it. It will not affect the varnish.
Denis

 

[Fitz]

Poly?

I have a project boat with similar peeling. I thought it was polyurethane, but not sure. Your's seems to be more gummy so maybe try the alcohol as Denis mentions.

If poly, I think you could thoroughly sand it with 220 (without going through all of the finish) and revarnish and preserve the patina you like.

 

[Andy Hutyera]

Sounds more like polyurethane that someone ill advisedly put over the original spar varnish. I doubt that it is shellac as shellac bonds well to almost anything. If it is poly, I suspect that Fitz's advice may be the best approach since clearly the bond between that top coat and the original has broken down - a common problem with urethane which should NEVER be used on a canoe. Even the labor intensive sanding approach may fail in the long run if any of the top coat is left on as eventually the bond of any of the urethane left may continue to break down. Other than alcohol (shellac thinner) any chemical approach to the problem will likely result in destroying the original varnish as well. Good luck!

From the looks of the finish, you might try using a small card scraper to get off the bulk of the crud before sanding with 220. I'd experiment with some judiciously applied heat and a small scraper. You want to soften the crud but the heat will also soften the original varnish so I'd be very careful with the heat.

 

[Blue Viking]

Out of curiosity, what is the serial number on that one....Looks like a Chestnut with those ribs...I have 2 and am always interested in those numbers to approximate mine to the same era... My two have the nice webbed seats...Does that slat seat look original? Good Morning all. Warm days and cold nites has kept the threat of flooding to a minimum over here in Maine .... Hmmm......Might even get in a paddle this week!

 

[Stephan]

Ok... So I picked up some denatured alcohol (apparently sold as methyl hydrate here in Canada) and used a cloth to rub some onto the planking and rib. The picture shows the results.

It's looking good but I was wondering what the easiest method is of using denatured alcohol to remove shellac. It's looking like I'm going to need to use a whole lot of it....

 

[Stephan]

Blue Viking:

It's actually a 1939 - 1942 Peterborough 16' Champlain High End. Serial # 1434 9850

 

[Denis M. Kallery]

Stephan,

When I strip furniture that is shellaced this is what I do.
First put on rubber gloves. Alcohol is absorbed through the skin and for me it makes my joints ache. Don't know what else it can do. Second work in a WELL vented area. Then I use a rag soaked in alcohol and apply it to a small area. Then take a coarse scotchbrite type scrubber, dip it in alcohol and work the area. Don't sop it though. When you first put the alcohol on let it sit a bit but not too long because it will evaporate fairly quickly -but that will soften the shellac. Work small areas. You can also use small brushes like tooth brushes to get into tight areas. After working it with the scrubber or brush wipe it with a cleaner rag soaked in alcohol. Let it dry. Some small amount residue should not hinder the oil based varnish from sticking. As Andy said shellac is compatable with most varnishes. It is in fact used as a sealer on furniture. This is not a wam -bam thank you mamn process so take your time.
Good luck and keep us posted with photos!
Denis

 

[Andy Hutyera]

You're very fortunate that the stuff is shellac! Try using a paint brush with the bristles cut off very short as an applicator and scrubbing with the shellac thinner. It will take a while to soften the shellac, but it should work. You may need a bunch of rags or paper towels.

 

[Stephan]

Whoa, you guys are quick at responding! Thank you so much! This is exactly why I posted my problem on the forum! Excellent advice!!

I will post more pictures as I go. Hopefully they'll help someone else who runs into the same problem.

 

[pklonowski]

You may want to think (very hard) about using a respirator, with filters for organic compounds. If this is methyl hydrate, it's a methyl-alcohol (aka methanol) based material. Methyl alcohol can cause blindness... and that's just the start of its impacts.

If you can find an ethyl-alcohol based solvent, it'll dissolve the shellac a little more slowly, will evaporate more slowly, and will only cause blindness if you consume it in very large quantities.

be safe.

 

[Stephan]

Do not consume in large quantities. Got it.

Just a quick shot for me and I'll pour a shot on the planking for the canoes that didn't make it.

More seriously, I will keep that in mind Paul, thanks!