Bleed-Through with Paint and Primer
A woodworker describes sanding problems and bleed issues with latex coating. May 28, 2010
Question
I am building an entertainment center and am using Ecoshield primer and paint from Dunn Edwards. The material I used was shop maple. When I ordered it, I just said paint grade maple ply, and that is what I got.
First off, it seems as though the primer stayed tacky, even after a few days. The can says 2 hours dry time to recoat. When you sand, it doesn't produce dust, just clumps. So I don't think this is right.
I noticed some reddish brown dots - it looked like something coming through from the primer. I sanded everything down prior to painting, and wiped it all down. So I painted anyhow, thinking the paint would cover the dots. Well, it came through the paint too. So I sanded it and sprayed Kilz primer and that did the trick. Then repainted. I had to use the paint, as it was specified by the owner and designer.
Why did it seem as though the primer didn't dry, and what is bleeding through, and how do I stop it in the future? I'm guessing higher grade material may fix the bleed through.
Forum Responses
(Finishing Forum)
From contributor M:
Did you thin the primer, and if so, did you use the correct thinner? Tell us a little more about your procedure. Have you used this material before with good results? The primer not drying properly means that the primer is where your problem started. For the most part, my primer failures have resulted from poor mixing, wrong thinner being added, or a bad can of primer.
From the original questioner:
I thinned the primer with a little tap water. It was so thick I couldn't get it to drip off the stir stick, and being waterbased, I figured that's what I would thin it with. I haven't used this specific finish. It is supposed to be environmentally friendly, with no VOCs. I just need to stay with the solvent based products where I'm comfortable, I guess. I didn't really have a choice on this job, and probably should have made a few samples.
From contributor M:
I would have thinned with water also. I typically stay with solvent based primers. I prefer to use a fast dry oil base primer, however I have noted that these will begin to dry in the can a little too quick. If, after having been opened, the primer begins to set up if not used within days, it will be lumpy and can not be thinned or broken down again. I get rid of it rather than run the risk of poor adhesion and other unpredictable results.
From Paul Snyder, forum technical advisor:
I had this discoloration happen one time with oak (it contains tannins) and that's when I learned about it. I can't remember ever having a problem with maple, but it may be that there was something on or in the wood that caused the problem. I did have a bleed through one time on apple-ply from the filler that was under the thin, top layer of apple veneer. Some woods contain water soluble extractives that will bleed through latex primers and paints.
It seems like there are more latex primers that gum up when you sand them than there are ones that produce a nice sanding dust. The two latex primers that I like to work with the most are Pratt & Lambert Suprime Z1013 (the other P&L Suprime with different numbers doesn't work as well) and Zolatone SP97. Both these primers dry in 1-2 hours in a warm, dry space and sand nicely. The SP97 also has great adhesion on laminates and other hard to paint surfaces.
To avoid bleed-through problems, use a stain blocking primer. Pigmented shellac (e.g., Zinsser BIN) is a top choice though there are latex primers that are also stain blocking... I just don't know how they sand since I haven't tried any.
From contributor R:
Not sure what went on, but I had a piece of maple, part of a 5 piece door, turn pink once. The primer had been applied and left to dry. Sanded it and second coat of primer turned... pink. Tossed it out and had another one made. Never did figure it out.
From contributor W:
Check what kind of primer coat you used. I guess it is a kind of oil primer or a kind of alkyd primer - if it is, it will take a long time to dry. Alkyd primer is also not compatible with nc lacquer. If you use nc lacquer, better if you use nc primer for the first step. It will make the finishing process much easier.
From contributor R:
From what I read on the PI sheet, they don't recommend thinning. Application by brush, roller or airless sprayer. That may be what caused the drying problems. Was this product in a metal can? The brown dots could be rust? (Even lined metal cans will rust if the product was sitting around on their shelves for a long time.) Run some through a cone strainer and check them out with a magnifier.
From contributor D:
I've had those purple-pink spots before too. Always thought it was from the UTC colorants. Makes sense that it's from the wood though.
From contributor A:
Those pretty purple streaks in poplar will often bleed through waterbased primer. Occasionally the dark streaks in soft maple will do the same. Oak should stain because of the higher tannin content, however, I don't remember ever painting oak. The stain often gets tied up in the primer and will not come through the topcoat. The primer in effect acts as a solvent to leach the stain out of the wood. Once it dries, it no longer has the solvent and the stain is contained permanently.
From contributor P:
Dunn Edwards Ecoshield is a water based primer. It does not have any stain blocking properties. My experience with the new eco-friendly waterborne coatings is that they do not perform up to par with their non-green equivalents. As for the red dots, I would make a drawdown sample on something inert like a piece of melamine. If the dots show up, submit your drawdown to your Dunn Edwards rep and ask for reimbursement for the additional products you had to purchase to correct the job.
