Troubleshooting Wrinkling in a Conversion Varnish Finish
Pros consider what might cause wrinkling on the second coat of CV on drawer front edges. April 17, 2009
Question
I have had this problem off and on for probably five years and have never figured it out. I used to use a lot of Mohawk stain and it only happened on their brown mahogany color, and yet it didn't happen every time only about every fifth time or something. My process is; spray a dye, stain and let it dry overnight, spray a coat of cv and let it dry usually over night, scuff and apply the second coat. I quit using the Mohawk stain and started using Zar oil based stain and I have had really good result from it for the last two years, then out of the blue it happens again. I can't figure it out because there is no pattern to it, the only thing that has been common on the times that this has occurred is that it’s a dark stain, (brown, slightly red tinge to it).
I thought I had it figured out that I wasn't wiping all the stain off good enough, but I did this time and it still happened. Funny thing is this only happens on drawer fronts and doors, never the cabinets. And when it happens it’s just on certain areas of the door, never the whole door. Many doors will look fine, some will have the wrinkled finish.
Also note, this only happens on the second coat of the cv, never the first. I have thought about everything in the world trying to correct this problem. Can't be weather because it’s done it in the summer too.
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Forum Responses
(Finishing Forum)
From contributor B:
Are you putting the cv right on top of the oil based stain? No sealer or barrier coat?
From contributor L:
Sounds like too much product is being put on. I assumer there were never any probelims when spraying the cabinets vertically, and the drawer fronts are sprayed flat. Usually that would be a solvent pop issue, but it seems like it could happen because of too thick of a wet mil coating.
From contributor D:
Nope, it's the infamous recoat window. All catalyzed coatings have a period of time during which they are subject to self lifting. This is the time between when the catalyst starts to cross-link the film and when the cross-linking is completed. During this time the new finish cannot dissolve the prior coat but can penetrate it to cause it to wrinkle as a sheet. The solution: get both coats done within three hours or wait 24 hours before applying the second coat.
From contributor B:
Since the only common factor here is the lack of consistency, it could be that it's most likely related to something the person handling the parts is doing. Food, hand lotion, cologne, hair gel, it's funny how the simplest things can cause issues.
I doubt that it could be a recoat window, since it is only in an isolated area, and the picture shows some pits next to the wrinkles that could be minor fisheyes. Wash the finish off with lacquer thinner then wipe down with Toluene (Toluol) using a very clean rag, never using the same side of the rag twice. Re-spray the part and let us know how this works to rid you of the wrinkles.
From the original questioner:
As I said in my process above, I let the first coat of cv dry 24 hours. I find that cv sands much better when it has dried overnight, I have sprayed the second coat within the recoat window with the same results. That was the first thing that I thought of when it first happened several years ago. I highly doubt there was anything on my hands when touching these doors.
From contributor B:
How about telling us what products you're using and if you are using a sealer over the stain. I've found that different cv's act something like your saying albeit not exclusively on doors or draw fronts. What exactly is your finish schedule?
From contributor J:
There are a lot of things it could be but I saw that same thing like what the picture shows, only in a corner and gradually getting better on the same piece. What I experienced was the painter didn't mix his catalyst in well and sprayed the part with unanalyzed sealer for a brief time. Then the second coat was applied and only the unanalyzed sealer, usually on the first part of the first pass would lift. We even duplicated it purposely. Just to let everyone know, sometimes the sealer didn't lift and we don't know exactly why.
From contributor R:
What solvents are you using with the CV?
From the original questioner:
I used to use Mohawk cv and now Chemcraft, both have done the lifting. I generally add a little reducer/retarder to thin it just a little. I found I get much better finish with this, as the finish seem to lay better. I don't use a sealer, just two coats of the cv. The first coat is scuffed and cleaned then the final coat of the same cv. The only other thing that I can think of that I use is that I clean the gun at the end of the day by spraying lacquer thinner through the gun. I always get all the thinner out the next morning before loading up with cv again.
From contributor H:
Are these pieces new work or items that have been stripped and being refinished?
From contributor G:
I agree with contributor L, and I think I know how it happened. Look to your gunning. I think every so often, you trigger early, giving an extra coat on some of the edges. I blew the picture up and looked carefully, but saw no signs of fingerprints or anything like contamination.
