What is happening to my clear finish?

[Mike Leonardo]

I have been doing a lot of paneling and built-in cabinet work using #2 pine. I've had a problem with areas of top coat delaminating (I think) and turning whiteish. I have tried various finishing techniques but the problem persists. I have attached a photo that give a representative sample of what the problem looks like. Some of it is much worse and more widespread.

I was initially using my tried and true finishing process. Minwax stain followed by Woodline Polyurethane. I typically thin the first coat about 10% with turpentine. After the first coat I sand with 320 to knock down any roughness and then follow up with a second and third coat. I try and recoat within 24 ours, or I scuff sand the prior coat with 320 if its been more than 24 hours. The delaminating tends to get worse with every coat no matter how long I let it dry and whether or not I scuff sand between coats.

Thinking maybe it was the poly, I tried another brand (Parks) and had better results, but the problem did still persist.

I thought maybe the issue had do be with the way I stain my work. I try to match my work to existing 60 year old pine that tends to run a soft "colonial maple" color. I probably use too much stain as I let the surface stay "wet" rather than wiping it down in order to get the right matching color. I thought maybe that was causing the delamination so I switched to water based stain.

The problem got better, much better in fact, but it did not go away.

I next tried switching to lacquer. Again, it was generally better better but still an issue in some areas. In fact the picture I posed is water based stain followed by nitrocellulose lacquer (Mohawk).

I should note that with the poly, the problem shows up within 24 hours although it does get worse over time. With the lacquer, it didn't start to show up for weeks. I should also note that I'm in interior California where the humidity is pretty low. I've had the problem happen in all kinds of weather; hot, below freezing, raining, dry, ...

I do a lot of work in oak, alder, and occasionally in vertical grain Douglas fir. I don't have this issue with any of those materials, even with my Minwax layered staining technique. So the only thing I have not changed is the pine. Not using pine isn't an option since I'm matching pine. There has to be away to finish pine without this occurring.

Any ideas what is causing this? Anyone else experienced this problem? Any suggestions on how to avoid? I have considered using shellac between the stain and the top coat, but some of this work is in bathroom and I don't like the idea of shellac as an undercoat.

One more thing, I've had this happen with pine from a stack of fresh lumber at my wood supplier as well as packaged pine wainscoting from a home store.

Mike

[Wayne Lomman]

White discoloration is usually related to moisture entrapment but may also be solvent entrapment and/or contamination. Given that it is only happening with the pine, I think you have to look at the timber. Is it too green or too resinous? If it is too green, you need to change your source of timber or let it dry before using it. Too resinous and it is best to reject it.

Having polished literally thousands of pine furniture pieces, it is best to use a fast drying solvent borne dye type stain. Follow this with a solvent borne pre-cat lacquer. If you must go the water borne route, use an alcohol/spirit based dye followed by a decent quality water borne lacquer. Which ever you choose, buy all your products from the same manufacturer following their recommended system. Then you can talk to them as well if it doesn't perform. Cheers

[Mike Leonardo]

I have been looking at one problem, but maybe there is more than one cause. The best results so far have been with water based dye and nitrocellulose lacquer. The worst have been with oil stain layered on followed by polyurethane. I suspect Wayne you are right that the problem with the dye/lacquer was moisture as that wood was pretty fresh from the mill and some pieces had a white residue which sanded off but may have been an indicator of moisture. We have had massive pine die-off due to bark beetles so the mills may be rushing the process. You may also be correct the stain/poly issue was caused by trapped solvents as the stain was a little tacky when I started with the ploy. That process has never caused me issue on oak or alder but maybe the resinous nature of the pine compounds that.

When you suggest a "fast drying solvent borne dye type stain", I'm not sure I know what you mean. I'm familiar with oil stains and water or alcohol based dyes but not sure I've come across solvent based dyes. I see you're in another part of the world, but is there a brand/line you'd recommend?

I've used pre-cat and post-cat lacquer and can use that for my shop work, but some of the finishing is at the site and spraying isn't an option. I'll concentrate on through drying of the material before I finish and try alcohol dye, or spirit dye if I can find it and hope it will work with poly too. I don't have much choice at the site for a top coat.

One related question. I installed some cabinet doors that I finished using the water dye/lacquer finish. The doors (mostly) came out fine. After I trimmed to fit the cabinet openings (flush mount doors) I stained the edges and finished with poly. The edges came out fine, but where the poly got on the lacquer finish it turned white when it dried. I was able to polish it off, but it added to my finish anxiety. I assume this is probably just the poly not being able to bond to the lacquer.

Thanks for the advise

Mike

[Wayne Lomman]

If you have to touch up on site, still use nitro. It is not worth the risk of incompatibility using poly. As for solvent based dye stain, I am able to buy it from Wattyl/Valspar, Pylon, Mirotone and others. Its base is typical solvents as used in nitro and pre cat lacquers. Your emission laws may mean these are not available. They are very quick drying, leave no incompatible residue and can be clear coated very quickly. I strongly advise avoiding mineral turns based stain. Alcohol based stain would be next best and water based provided it is absolutely dry. Cheers

[John Sanford]

When you changed poly, did you change turpentine, or are you using the same turpentine to thin the poly?

[Mike Leonardo]

I don't religiously use turpentine to thin. I do it most of the time on the first coat though. While I can't swear to it, I have probably used normal paint thinner to thin the first coat when I didn't have turpentine. And I have experimented with putting the first coat on full strength. None of it seems to stop the de-lamination.

I have not changed brands of turpentine. Truth be known, I can't even buy turpentine in CA anymore so my choices are limited. I can't even buy real paint thinner here.

As to solvent based dye, I did find a local supplier of a Mohawk product. But its acetone based and drys so fast it must be sprayed. I may give it a try, but I'd rather not have to spray the dye too. I think I'll try alcohol stain before I resort to spraying although I bet it dries pretty fast too.

[Steve Schoene]

I do suspect moisture levels in your pine, as one factor. Your description calls in no.2 pine. Common lumber is not dried to the levels of furniture grade lumbers. If acquired from standard lumber yards, it might come from the mill at just under 19%. From higher end lumber yards you might be able to get lumber kiln dried, which for common lumber would be a bit less than 15%. I'm not very enthusiastic about wood from box stores, even in trim packages. I'd check moisture levels.

Possibly more important is whether the resin in the pine has been suitably "set". This requires that the wood has been kiln dried to at least 160 degrees. That level is not necessarily achieved in modest kiln dried. To get that you might have to spring for furniture grade pine ie. select grades C or D. Unfortunately prices are much higher. Unless set resin will attack top coats.

[Mike Leonardo]

Moisture and/or solvent entrapment seems like the likely culprit. I need a lot of pine as I'm also making 1x12 T&G paneling for three more rooms. Furniture grade pine would make it cost prohibitive. What about air drying before use? Its soon going to be 100 degrees here in Central California. Would not be too hard for me to sticker my supply and let it dry for a while.

I understand the problem with resin. I've seen that around knots and pitch pockets or streaks. That seems to be limited enough to not be a big concern. On my cabinet work I usually try and cut around those areas and on paneling it doesn't seem to stand out that much.

[John TenEyck]

If you are selling cabinets made with anything less than kiln dried material you need to rethink what you are doing. You also should have a moisture meter to check the lumber you are receiving to confirm it meets what your supplier says it is, and to determine when it's at EMC with your shop.

Look at Sherwin Williams' BAC Wiping Stains, if they are available in CA. They are solvent based but can be applied by hand, and can be top coated in an hour or two.

John

[Mike Leonardo]

Good point. I should have said that in this case I'm my own client. The advise is probably still valid though, especially for the cabinets, but at least I don't have an unhappy customer complaining about my work :-)

Funny thing is I've been using #2 and #3 pine for decades without any issues like this. Its only been the last two years I've had these issues. I always assumed the pine was kiln dried but can't say that I ever verified it. I don't normally buy pine at home stores anymore, but is that pine typically kiln dried?

We only get about 10" of rain a year here and except for midwinter fog the humidity is very low. I wonder if the clean air finishes available today are less forgiving than prior ones.

I'll check out the Sherman Williams product.

Thanks

Mike