Sealing Black Cork

I made decoy in Al McCormack's Basment for years. Now, Al was a very funny guy and very set in his ways. All of his stools were made with Black Cork. His method was Spar Varnish the cheepest you could find. Paint the bird with it then dip your hands into the cork dust and smear it all over the bird filling in all of the holes as best you can. What a mess! Let dry and then fill in the big holes with plastic wood and then another coat of Spar Varnish, let dry, sand and paint. I always use to think that Tompson's Water Seal would do a better job. but there was no arguing with Al
 
Many of us still do it that way...............well maybe not the part about dipping your hands in it. While I'm not a prolific carver the few black cork blocks I have done recently were sealed with Spar Varnish. I can't remember if I thinned it for the first coat or not but it wouldn't hurt.
 
I read you want to total dunk them for at least 15 minutes. If you have epoxy, you can thin it down and use it instead.
 
Andy,

If you have a bucket with enough depth to dunk, have at it as that would certainly seal all the pores.

Regarding epoxy, you don't 'thin' epoxy as it is not a solvent based product, the best you can do is heat it slightly so it thins itself. But be aware that it "thins itself as it kicks over" so you won't have much time - not something I would recommend as it is too unpredictable.
 
Andy,

If you have a bucket with enough depth to dunk, have at it as that would certainly seal all the pores.

Regarding epoxy, you don't 'thin' epoxy as it is not a solvent based product, the best you can do is heat it slightly so it thins itself. But be aware that it "thins itself as it kicks over" so you won't have much time - not something I would recommend as it is too unpredictable.
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I was definitely told to thin the epoxy, but I can't remember with what exactly. It was just for the first coat also. The second coat was just thin epoxy. I will ask next time I talk him, which could be later this afternoon. If I can get done with work soon enough. I seem to remember someone on this site mentioning alcohol to thin epoxy, but that is not what I think was mentioned for coating the cork.
 
Acetone or alcohol will thin uncured epoxy, like when you want to clean up but I'd be real concerned that it wouldn't allow it to cure properly if you tried to thin a quantity of it. Personally, I think you are asking for a big mess but who knows, I might learn something. Let me know how it comes out.
 
I have thinned epox with Alcohol. It sets up fine. You mix the the alcohol in the hardener and the resin before combining them together. The mixture will look milky. Alcohol as far as I know does not chemically bind with the polymers. It flashers off when the expoxy cures. I have used this on airplane wings with thin cloth where weight is a consideration. I don't know about any other solvent. They might chemically bond ?

Black cork decoys... I haven't carved any but they seal cork floors with varnish. I have sealed syrofoam decoys with shelac, that worked well. It provides a good base for paint. It also seals well.

I would not use concrete sealer on decoys. One for health reasons,nasty stuff. Thomsons water sealer or other like sealers are just varnish thinned down. Its much cheaper to buy varnish and thin it yourself. Now I will have some chemist flame me...( ; )
 
If I remember correctly McCormack didn't thin it at all. It was a sh--y process at best. It was 35 years ago at least when I was making stool with Al and I'm still cleaning my fingernails. But the decoys held up I still use them, and the Black Ducks still love them. I don't know if I like the idea of the epoxy thinned or straight. Epoxy by itself has no strength and is brittle with out a binding materil like fiberglass. If it encapsulates the cork rather than combing with it I think it would crack very easily. I'm not sying that it won't work but I would like to see a decoy thats made with this method. Probably if you thin the epoxy with Acetone or Laquer thinner you would get much better penetration. The varnish remains flexible but the Stools do dent.
 
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I found my notes the cork was brushed with a coat of epoxy thinned 50% with acetone, then voided filled with body filler, then finally another coat of thinned epoxy.
 
Thinning the epoxy makes Sense to me. When you bang them do they crack? I bet you that thinned Flex Coat would work well too. I'ts an epoxy that I use to seal the windings on fishing rods it remains plyable after curing
 
That's interesting Andy. I wonder what, if any, properties are degraded because of the thinning. I might have to do some experimenting to get a feel for it. Thanks for the info.
 
Pete and Andy, I have no idea if acetone degrades epox. However when you read the back of the can. Health hazards rubber gloves it absorbs through the skin, respirator for breathing.

Alcohol won't kill you..... unless you drink to much.( : )
 
I've been working on a bunch of black cork bluebills right now, and over the past month have experimented with a slightly different technique.

Take a jar of Titebond II glue and make a mix of 25/75 glue/water. The consistency will be like skim milk. Then take the bird and dunk it (like mentioned with the spar). Allow a couple days to dry, depending on ambient temperature; it's been chilly here in KY... Then take the bird and dunk it a second time and allow to dry.

This technique does two things: it acts as a binder for the cork, as the adhesive is infiltrating all of the pores in the cork. It helps to beef up BSC... It also acts as a sealer, as Titebond II is waterproof. I can tell you, it sets up rock hard!

I just tried this technique this year, so I don't have any experience as far as gunning over the birds yet. I will be putting 13 birds out this coming fall that will be finished with this technique.

One of the great things about decoy carving is that it is a never ending experiment.....

Best,
Steve
 
Hi Steve,

Where do you get your black cork, and what do you normally use to shape it? I am going to do sort of an old school rig of black cork scoters this summer. Just looking for some pointers.


Best,
Nate Grace
 
I've used spar varnish.

First coat thinned 50% with turpetine. Second full strength.
Both brushed on.
Didn't bother with filling.

Not a big deal process.
 
Nate, Just use a Sure Form file or an old rasp to rough them in and finish with some
50-80 grit paper. I use spar varnish and fill major voids with cork dust and Tite bond or
rubber cement. John
 
Nate,

The best tool I found for shaping was a big honk'in half round bastard rasp. Mine is about 18 inches long I think - really good for a two handed hold. A Sureform works ok but I found mine to get full of cork boogers too easily. I used a modified shave horse to hold the cork. I had an old fleshing beam anchored to the floor that I was able to put the cork on and jam a 2x4 against it and the wall to hold it in place. Wasn't long before I had a big pile of black cork dust.
 
This is waht McCormack Used for shaping His files were used Horseshoe Files He said the Shoer would oly use them once and give them away. I still have one 35 years later, His Sand Paper was cut for sheet of Hardwood floor Sandpaper. If I had to guess it was about 12 grit. On Long Island his Stool are ledgendary.
 
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