Troubleshooting a Wrinkling Problem
A clear conversion varnish sealer is wrinkling in a few spots over an oil-based stain. What's the problem? July 11, 2013
Question
I’m doing a match up job and I’m trying to duplicate the color of an existing kitchen for some new cabinetry. It’s similar to a very dark purple with some hints of black/blue in it. Here are my steps and then the problem:
Step 1: Wipe ebony Minwax stain over shaker door. Door is built with maple stiles/rails and 1/4" veneered MDF panel inside. The panel is nailed to the back of door fitted like you would a glass panel with a dado on back.
Step 2: After 24 hours wipe again with custom purple solvent based pigment stain.
Step 3: Mix about two ounces of the purple stain with a quart of catalyzed conversion sealer and spray toned coat.
Step 4: Twenty four hours later spray un-tinted conversion sealer to seal in all previous coats.
Here’s the problem: during Step 4 the front of the door looks great - nice tone, no issues, but the back of the door only is showing spots about half the size of a penny where the pure (un-tinted) conversion sealer is wrinkling. As it dries I can literally take this wrinkling area and peel off the finish. This only happens in the back, close to the edge where the MDF panel is nailed to the solid wood and filled with acrylic putty.
Any input on what happened here? Why is it that only the pure conversion sealer is having this reaction and not the same sealer mixed with pigmented stain?
Forum Responses
(Finishing Forum)
From contributor C:
If I had to guess, I'd say it's the Minwax stain. I always allow two to three days for an oil stain to dry before top coating. If you mix a little in with your finish it allows it to work. Just like fish eye eliminator which is actually the stuff that causes fish eyes, but when mixed in it will allow the finish to work - kind of like what you've done. You need to get the stain completely dried out before spraying over.
From contributor F:
Never mix
Minwax stain in with any type of coating with the possible exception of oil based varnish/poly.
Minwax has too much oil in it and will cause no end of problems with cross linking coatings like CV. I suspect the
Minwax may be interfering with the cross linking of the catalyst and that in turn causes a re-coat issue. Essentially this means the first coat cannot completely cure and the solvents in the second coat are attacking the first coat as if it were a paint stripper.
The custom purple you mentioned could also be an issue. You did not mention what brand it was, but in any case two coats of wiping stain are probably too much and you may be leaving too much pigment on the surface before sealing which will prevent the sealer from getting a bite on the wood and this can also cause lifting/wrinkling.
Now as to why this only happens on the back in certain spots, I have no idea but to me it's not the main issue anyway. A much better way to match the finish is to use a dye stain on the bare wood, followed by a more professional grade wiping stain like MLC, Valspar, or Chemcraft and if you still need more color then put some dye in your finish to make the toner instead of wiping stain.
From contributor G:
I agree with the previous post. Your problem it is not in the final coat of sealer it is in the oily stain mixed with the first coat. Dilute the stain in lacquer thinner and don’t use more than two ounces of stain p/gallon of CV.
From contributor M:
Agreed with the above, your problem is almost certainly where you mixed the stain with the sealer. There are colorants you can do this with - ML Campbell's Microton dye and Sherwin William's aniline dies. They are made specifically to be added to solvent based products.
I would suggest the following schedule, and suggest very strongly against using a tinted dye in a sealer, but rather in your topcoat, because you do not want to have to sand very hard your tinted color. You're asking for potential problems with sand-through and uneven coloring.
1. Get something other than Min-Wax. Get a legit industrial stain color matched up because most have a one-two hour cure time. Wipe this stain on, wipe off.
2. Seal with coat of clear sealer. Cure, and sand flat.
3. Seal with one coat topcoat clear. Cure.
4. Mix your tinted topcoat in a cup gun and thin it 30-40% with standard lacquer thinner. Spray a very light coat. Use enough dye to get the results you want (record how many mL of dye you added to how many mL of finish). Make this about two wet mils.
5. As soon as you shoot the door with this tinted color, let if flash off for a minute or two, and immediately topcoat with clear, three wet mils. This process has worked wonderfully for me many times.
From contributor T:
I would guess that there is oil from the staples/nails causing fisheye. Try cleaning the backs with denatured alcohol before going further. You might be able to brush some color onto the spots wait for them to dry. Spray a light mist of CV onto the backs and let it sit for a couple of minutes before applying a full wet coat.
From the original questioner:
Since the problem started it has only been on the backs of drawer fronts so I wasn’t too bothered but there was a small spot on the back of two doors, those were my concern. One door I kept sanding down the wrinkle flat and shooting sealer over it repeating the process again and again and the wrinkle in the exact same spot continued to show. The other door I sanded straight through to the bare wood, started the process over in that one spot and it was a success. Now you can see that outline. I’m not sure what to call it but it looks like the outline of a continent where the area you sand down is lower than the surrounding area. I always wondered why when that happens you can’t rebuild the area with fluids alone.
From contributor T:
I'm late to this discussion and everyone is throwing out a lot of speculation on your finish choices. I've been a finish artisan for 30 years. You haven't stated exactly what you are spraying. I've read your post several times and I'm guessing you are a small shop and are spraying your panels flat. Call me crazy, but I've taught many seminars over the years and it sounds like fingerprints - only on the edges of the underside, and only on the clear sealer. I'm guessing that somehow there is residual oils from finish or sweat, either will cause what you’re speaking of. What everyone else is stating should not limit itself to only the outer edge of the underside. Depending on what you are working with, those areas can be buffed out by hand with a soft cloth by stoking carefully in one direction to spread the peel. It sounds like a cleanliness and contamination issue and not the finish or stain.
From contributor M:
The other (potential) reason for it happening to the back panel, near the edge, is that it's easy to not wipe the stain out of such corners as this. It's common for folks to fail to wipe the stain sufficiently out, leaving a heavier film. Combine that with the fact that you are at the edge of a sharp corner, where solvents and vapors can wick up into the edge of your grain, and with the fact that you are mixing in an oil-based stain with a solvent-based conversion varnish sealer (incompatible mixes equal weak finish), and you definitely have a recipe for wrinkling. This is even if you've cured the
Minwax for 24 hours.
From the original questioner:
Contributor T you’re right. I did not mention specific names - my very first coat of wipe-on stain is a
Minwax ebony. The second wipe on and the stain mixed with the conversion sealer is something called “premier finishes” I think. There is only one store here that will custom mix an oil based stain starting from a clear base. The conversion sealer and CV that I’m using is all Gemini.
I have used this system for about two years now and the finish looks great and so far nothing has failed, this is the first time it has wrinkled on me, just weird that it’s only on the back and only on the edges where the back is nailed to the inside of the dado, and one spot on the back where the rail/stile meet that are nailed together, filled with acrylic putty.
I know these oil based stains are not the best thing to combine with CV and I have made steps to switching to NGR stains from Gemini. I even have about 5 gallons of the clear base and a quart of each color but I’m still not confident with how to mix and apply the colors to get what I want.
From the original questioner:
Contributor M - yes every time I do anything with
Minwax, whether it’s used as a wipe on and/or a toner mixed with sealer. I let it dry for 24 hours, although I’m thinking at some points during that 24hours I’m sure it has dropped to under 70 degrees here, do you think that was an issue? I was dealing with a rushing client so I was going against my better judgment but I didn’t go under 24 hours.
From contributor M:
I've used the
Minwax ebony before, it's really loaded with pigment. It's possible that it cured slower than you'd want, especially if it was rainy/humid outside at any point. I can't say with confidence.
The only thing I do know with confidence is that mixing any oil based stain with conversion varnish/sealer is, at some point, going to cost you money and agony. Do yourself a strong favor and buy a quart of each color of ML Campbell's Microton dyes, or Sherwin William's aniline dyes. They are expensive but they go a long way and are specifically made to go into nearly any solvent-based finish. I've used them in CV, lacquer, and 2K polyurethane. I think your problem is a compound issue, not something you can point to and say "ah, there is the evil". A slow drying stain, mixing oil stain and CV, and throw in the possibility of problems with the edges of the MDF allowing stuff to lift, and possible slow curing or insufficient wiping and viola, you get wrinkles.
From the original questioner:
Contributor M I appreciate it. I wonder if the NGR stains I bought from Gemini will do the same thing as the dyes you talk about from ML Campbell. You say that mixing the oil based stain with the cv will cost me money and agony at some point - do you mean possibly the clear coat failing after a few months? The jobs I already have done came out really nice. Every now and then I try to sink my nail into the clear coat and it’s very hard, is that a definite sign that clear is on there good?
From contributor M:
I can't wager a guess on the long-term durability, but what you've done is adulterate the conversion varnish with a contaminate. I would personally suggest you stop doing it, but I also do not have any hellfire and brimstone prophecy of imminent failure. If you have a problem, chances are it will be in areas that have a lot of moisture (bathrooms, near kitchen sink, dishwasher, over the stove). If that happens, replace the doors there with properly done doors and remind the customer that a slight color difference is due to aging of wood, since you probably won't get an exact color match anyhow. You will have wood aging, and slight coloration difference from using a different colorant. The NGR from Gemini will probably work as long as it's an alcohol or acetone base. A call to Gemini will be good assurance, but most NGR dyes I've seen can be safely mixed with solvent based finishes.
From the original questioner:
The problem is that there is nobody over here that I can go to for that quick assurance or advice. We are the guys that the other guys come to, believe it or not. We are in the Bahamas and are one of the only shops that even know what CV is! We don’t have that much issue with temperature as it seldom drops below 70 and I know CV hates the cold, but we have humidity issues. I’m only just learning about relative humidity, etc. and moisture content of wood but I know when my conversion sealer is turning white as it dries. Maybe it’s not a good time for spraying.
From contributor A:
Is this only happening in the spots where you applied the acrylic putty? That is how it sounded. If so have you done a side sample over that same putty to see whether that is the issue? If so, then sand back to bare wood to remove all of the putty and proceed.
From contributor M:
One nice thing about adhesion issues is they will always tell you what the problem is. Just look through a magnifier and see where the finish peeled off. Is it between layers of stain? Wherever it is came apart, that is your weak link and that is what must be corrected. I would never use
Minwax stain with a high tech finish. I don't like the long dry times, the opacity of the stain, and if there is a problem I can guarantee you that the manufacturer of the CV will point to the stain as the problem because it isn't their product that is designed to be used in their system. Let us know where the failure occurred and we will be able to help you better.
From the original questioner:
Contributor A - I thought that but it is not happening over every spot where the putty was because behind each panel I must have put like 10 or 12 18g nails all countersunk and filled with putty. I have used this same putty after nailing 3/4 x 2 solid maple frames to plywood with no reaction whatsoever. Now I do know that in some spots where the nail went in and I was pressing harder on the nail gun the nail caused flakes of the veneer to come off of the MDF, leaving areas of MDF exposed. Maybe the problem is there? Has anyone for any reason ever applied conversion sealer or varnish to MDF?
Contributor M - I think I have a magnifier around here somewhere and I will have to try that out, although those doors were installed today and the client loves them. Even though I am not happy with them I know I have to stop using stains like Minwax, however even though I have some GEMINI clear base and NGR stains ready to be mixed and matched to create colors I have no confidence with them yet.
From contributor M:
NGR's are cake. Follow this procedure:
1. Use wiping stain of your choice, fast drying, to give you grain pop and base color.
2. Seal, cure, and sand.
3. Mix small amount of NGR dye into a mix of highly thinned clear finish. Experiment with various amounts to get the darkness you want in one spray coat. I use a 50/50 mix of conversion varnish and standard lacquer thinner (for fast flash-off). This very thin mixture allows you to spray a very, very even coat of this dyed varnish.
4. Spray 1-2 wet mils of this dyed clear, let it flash off for 30 seconds to a minute, and then topcoat with three wet mils of clear.
Literally it's only a half-step more time, you are only spraying one very thinned, but dyed, clear on your item, followed by a quick flash-off of the solvent, and then three wet mils of topcoat, and done.
