Sealer or something between alcohol stain and polyurethane

[Cesar Vega]

This is the first time I try this finish.
I put a coat of alcohol based stain, a dark color, over pine.
The stain dried for 48 hours.

I tried a coat of polyurethane diluted at 50% with the proper solvent.

Now, when I pass the brush, it is removing the stain!
Not to the point to have the wood in natural color, it is still dark, not as dark of course, still dark, but yet it removed a lot of stain. I tried this in the back side of the furniture I'm building.

What's going on? Should I had put any sort of sealer after the stain and before the polyurethane?

Oh, I also tried with a spare piece that was stained two weeks ago, so, the diluted poly also removed the stain, so, I don't think the problem is related to stain drying time.

What it could be then?

[Tim Lawson]

I'd suggest using shellac to seal in the stain. Either make it up from flakes or use an off-the shelf product like Zinnser. Make a trial piece and test how many coats of Shellac to use. You can put on multiple coats in a few minutes and then wait maybe 5 minutes for it to harden (you made need a longer time - so experiment).

[Steve Schoene]

HO, don't use shellac as a sealer over an alcohol soluble stain (I assume dye?)--that would be about the worst choice. It will redissolve the dye causing the color to migrate into the coating. An oil based varnish will go directly over an alcohol soluble color without problems.

But, did you really use an alcohol soluble dye, or did you use a concentrate that can be dissolved in water, alcohol, or oil, such as TranTint? With such a dye, it doesn't matter which solvent you used to apply the dye, it still remains soluble in all of them.

In the latter case, you could use a shellac sealer--BUT, and it's an important qualifier, if must be sprayed over the dye, preferably in a light, dry coat or two so it doesn't redissolve the material.

[Cesar Vega]

Shellac was also my first thinking, but later I thought that might dissolve the dye as well.
And the tint I used, is marketed as "stain", it is 100% soluble, no shaking/stirring needed, it had no solids. I think that's a dye, right?

Well, I tried the 50% diluted polyurethane to act as sealer, as it was suggested in the manufacturer website technical documents, and was also told by the seller in the store. I guess, that just doesn't work in stained wood.

Now, they also have a product called "Polyurethane sealer", supposed to be used prior to the full polyurethane. But it wasn't in stock when I got the poly and the solvent, so they told me just dilute to 50%, the solvent used is labeled a "polyurethane solvent", sort of thinner I guess, by the smell.

So, last night I went to a different store, close to home, explained to the guy on charge and had no idea what was going on. He got some other guy on the phone which had no idea either.
Finally, I suggested about the poly sealer, which this store had in in stock.
The guy said he knew it was a very different product, different resins.
Well, we tested in a sample I had previously stained and luckly, it didn't remove the stain. This sealer thingy smelled more like an alkyd varnish and it was very liquid, almost like water.

Well, I will try the sealer tomorrow.
Today I will try to remove the mess I did in the back of the table by simply applying the same poly solvent I got and try to stain again, though, I'm not sure if the stain will go to the wood or be kept on top of the thin layer of poly left by my previous attempt... :(

[Steve Schoene]

Brand names would help a lot. There are some "NGR" or no grain raising dyes that come pre-mixed, but marketed as stain. There are some dye stains which combine a dye with a binder, though I don't recall any of these being alcohol soluble.

Now as far as "polyurethane sealer" you do have to be sure that the polyurethane top coat is compatible with the sealer--ie. made by the same company and specifically recommended for use under that particular top coat. Polyurethane varnishes are very picky about what they will adhere to, so mixing one brand's sealer for polyurethane with another brand's polyurethane varnish many well not work well.

[Scott Holmes]

A light spray coat of Zinsser Shellac from the aerosol can is the quickest and least complicated way to seal in the dye/stain. If you brush it may lift the dye though you may have had an oil soluable dye in the can of "stain".

Don't see where anyone warned you... the shellac you use MUST BE DE-WAXED or the poly will not stick.

What are you finishing and why did you chose poly as your varnish type? It's for floors.

[Cesar Vega]

Hi,

The "polyurethane sealer" didn't work either. I think it worked in the store, because my stained sample already had some dried poly on it.
But it didn't work in my stained wood at home.

The furniture is a small computer desk, almost like a table.
I want durability, and a non shiny finish.
I would like to choose alkyd varnish, but there are not too many choices here.
Please, note I'm in Mexico, not in the USA. All what I found in stores is Polyurethane varnishes. When I ask for alkyd the try to give me spar/marine (phenolic), which I recall gives a sort of rustic finish.
Prior to this I used minwax in a few projects, always. Now, I choose this line of products (Polyform/Comex) just because they had a very nice chocolate stain... so I decided to try the whole system: stain/sealer/poly.

Funny side is the I went back to another store, and told the problem and they just don't know what could be happen. They just swear it shouldn't be. A guy which looked like a director who happen to be in the store when I arrive, even suggested me to take the furniture to their training center and see if any of the finishing genius there could find the culprit thing! lol... well, I might do it.








A light spray coat of Zinsser Shellac from the aerosol can is the quickest and least complicated way to seal in the dye/stain. If you brush it may lift the dye though you may have had an oil soluable dye in the can of "stain".

Don't see where anyone warned you... the shellac you use MUST BE DE-WAXED or the poly will not stick.

What are you finishing and why did you chose poly as your varnish type? It's for floors.

[Cesar Vega]

Hi,

Yes, it is an alcohol soluble dye.

Well, I got a bottle of the zinsser shellac.
Made a test in a small sample, sprayed the shellac, waited like 90 minutes, then tried the polyurethane sealer on one side and the poly at 50/50 on the other half, the piece of wood was stained 3 days ago.

Both worked very well, they still remove some dye, but very little.
The brush was just slightly tinted:
a)The poly sealer removed like 1-2% of the tint it used to remove.
b)The poly at 50% removed like 5%, roughly.

In anycase, the tint was not mixed over the wood causing the look of an tinted varnish as I was getting last week, which is a big gain.


I think in order to get perfection, I just need to either apply more shellac, or wait more time to get it well dried.

I'm still scratching my head on why on earth I would have to use a 3rd product in the middle of a "system". I'm starting to think their products just have to much solvent to be applied by brush... :(.... yet they say they can be brushed.



A light spray coat of Zinsser Shellac from the aerosol can is the quickest and least complicated way to seal in the dye/stain. If you brush it may lift the dye though you may have had an oil soluable dye in the can of "stain".

Don't see where anyone warned you... the shellac you use MUST BE DE-WAXED or the poly will not stick.

What are you finishing and why did you chose poly as your varnish type? It's for floors.