Waterborne Peeling over Stain

      Troubleshooting advice for a case where a waterborne topcoat is peeling away from an oil stain. May 18, 2010

Question
Two weeks ago I finished eight interior raised panel pine doors, jambs, and 45 pieces of door casing. This is what I ended up doing:

Sand wood to 220.
Two coats of minwax stain let dry two days.
Spray one coat of mixed 2#cut of dewaxed shellac let overnight.
Sand 400.
Spray two coats of target wb em2000.

One week later after sitting in my shop at about 59 degrees I could peel the finish with my finger nail. I talked with someone at target and I was told the finish should be fine but needs to cure at a warmer temperature. I brought everything to the job and installed the doors but did not trim them until I saw if the finish would be ok. One week later at 70 degrees I can still run my fingernail down a piece of casing and the finish bubbles up the whole length of where I run my finger nail then I can just scrape it off. I think it might actually be the shellac coat peeling off of the stain. Iím not sure what to do it would be hard to sand down all of that colonial casing. Could I use a spray stripper and ScotchBrite pad to remove the finish and re-stain? Does anyone have any ideas what could be happening here?

Forum Responses
(Finishing Forum)
From contributor Y:
If you let the dye/pig stain dry for two days at 59 or less with little or no air movement it may not have been thoroughly dry. Have you tried to pull it up with a razor or exacto knife to see if it disadheres in a sheet? If it is sheeting, then you have a major problem, if not, time alone could be helpful as the gassing of the mineral spirits or other solvents continues to take place. Seldom do I hear of shellac not having anything less that excellent adhesion, unless faulty finishing practices are to blame. Even if the pine was turpentine knotty pine shellac would have had good adhesion. I'm presuming that this work was clear pine?



From the original questioner:
I can get under the piece and sometimes I can peel off about a six inch long piece and other spots I can just pick off small pieces. After I stained them I ran a fan on them for two days and at night the temperature went down to about 58 and up to about 64 during the day. It seems it is peeling down to the stained wood which is clear white pine. How can I tell if it is the shellac and wb top coats or just the wb and what would be the best fix short of buying new casing?


From contributor R:
Minwax stains are full of oil. They are notorious for taking a year and a day to completely dry. Without a doubt the stain was not dry (I know it looked dry and it felt dry and it smelled dry but it wasnít) when you coated it. Unfortunately it looks as if you have to start over from scratch and this time around try and mix up your own stain to match the Minwax color. Iím not a real fan of applying any type of water based coating over an alcohol based shellac.


From contributor O:
If there is an ML Campbell distributor near you they can give you Minwax colors in their Woodsong II stains, which are dry in about an hour and are a far superior product. I have successfully applied wb topcoats directly over them many, many times. Given the finicky relationship between solvent stains and wb topcoats I like to let the stain dry overnight, although I have pushed it to within a couple hours once or twice with no problems.


From contributor P:
You can put a couple of drops of methanol or denatured alcohol on a spot you've peeled the finish off of and wait a minute and then rub the spot with your index finger to pick the alcohol up and then swirl between your finger and thumb if it gets tacky and sticky then the shellac is still on the wood. If not then do the same with the underside of the piece you removed if it fells sticky then itís still attached to the WB coating. Either way you will probably have to strip and start over or buy new casing as you said. Seeing as the WB coats are an alkyd mainly, most of your klean strip removers should strip it. Then you have to make sure you get all of the residual wax off afterwards.


From contributor N:
P220 is for between coat sanding. There is no need to go beyond P150 on pine. Also, Minwax is way too oily. The Woodsong suggestion is excellent. Also, you need the heat, and with waterborne more importantly good airflow over the work, right after application. A week later doesn't help.


From contributor P:
I used to use WB finishes over oil-base stains like Miknwax a lot and what worked best for me was to add an ounce of Japan drier to each quart of stain before use (4 ounces per gallon). Also, keep the wood above 65 degrees before, during, and after the finish is applied. Adding the Japan drier to the stain will make it dry overnight in most cases as long as you keep it warm and in a well lit area. Without the drier, it can take days (sometimes weeks) for the stain to dry when the temperature is low or the humidity is high. You can tell if the oil-base stain is dry by feel and odor with some experience.


From contributor G:
"I think it might actually be the shellac coat peeling off of the stain." First - was it stain and not polyshades? Second - if it was stain, did you wipe it before letting it dry?


From the original questioner:
Yes it was stain not polyshades and no I donít think I wiped it as good as I should have. My rag was pretty saturated with stain when wiping so I am sure I left a film of stain on the trim. Although I let it dry for two days with a fan running it was cool in my shop.



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