Our finishing is done by a independent finish shop. It is conversion varnish. The shop has a large rollup door, often partially open. I would call the climate in the shop "semi" controlled. This is in the Pacific Northwest- high outside humidity in the winter. In the fall, I have started to notice a slightly milky look to the finish, and occasional hazy white spots here and there. Is this a temperature-humidity problem? Is there anything else that could cause it?

It’s blush. Too much humidity trapped under the finish.

There are several variables that can cause this effect.
A) check the bottom of the pail make sure no settlement of flatten paste.
B) no air movement flowing over finish as it can trap active solvent from off gasing.
C) atomized air at the gun 16-24 psi
Too much air will cause premature skimming.

Hope this helps

Thanks for the replies.
The manufacturer info says spray temp. minimum is 68 degrees F.
Not sure about what pressure the applicator is using.
It is not flattening agent as far as I can tell.

Not sure if the finisher is using a reducer- I will check. There is a bit of a break in our production so no recent results to look at.
I will set them up with some samples to see if the problem can be isolated- it has the potential to be devastatingly expensive, as there does not seem to be any corrective action that can be taken , except re-milling the entire job. .

On a side note, throughout my career, maintaining quality from sub's has been the single biggest stress.

More trouble.
I printed off this thread , gave it to the finisher to read. Bought a hydrometer and thermometer for his shop. Had him keep it to 70 f and shoot some samples. They were acceptable.
Then brought up a couple of jobs to do and they have blush-milky looking finish. The maple is sort of acceptable- the cherry looks kind of light, and the sapele looks sort of dull with a pink cast.
He had to suspend work because it was hard to keep the shop warm enough, we had a cold spell.
He is using the recommended reducer.
Is there a reducer made for colder weather use?
A finish that has a dull rubbed effect that is durable and usable in colder weather?
I am so tired of this.

I don't think I've ever had an issue with 2k poly or acrylic blushing. It's also just a better finish than CV in just about every way other than cost, but in my experience the cost isn't really that much more. The finishing process is almost identical minus some extended drying times on the primer, but it's not usually anything crazy.

I also believe water borne don't really blush. Some of the catalyzed waterbased polys are really, really durable finishes. probably exceeding that of CV.

I don't care about product cost. Just a good finish. We don't use a lot of it, it goes on high value product. I just want something forgiving my finishers can use without problems.

Can you post a pic? While I think it’s blush I have to admit to having shot a lot of CVs in colder than needed conditions when I was young and poor. Never an issue. What brand of finish? have you checked he’s using the right catalyst and right amount of it? How thick is he laying it on? Shooting CV is not terribly difficult and it’s pretty forgiving. Something is off. Where are you located? You would have to have some crazy humidity I think to keep causing these problems

Here are a few pics. The problem wood finish is the piece in the middle, control samples to each side. Note the grey-pink haze, all the grain definition and wet look is gone. The maple lost all amber overtone, the finish made it bone white.
Looks like someone mixed dog crap with mud and shot it on. Can you tell I am upset about this?

View higher quality, full size image (576 X 432)

View higher quality, full size image (576 X 432)

View higher quality, full size image (576 X 432)

Doesnt look like blush to me. Whenever i've had blush its pretty inconsistent, blotchy looking.

What product are you using? I remember there was a precat I used once, when the finish went on too thick the flattening agent would settle and look something like that.

Finished could be over catalyzing, I've seen similar results when thats happened before.

All blushing I have ever seen/had has been when spraying precat lacquer and it comes and goes. It’s not uniform like this across the entire piece. It has an uneven appearance to it. Are you sure he is spraying the same product as the samples. It looks like bad water white finish or more aptly old school water born with the bluish hue. Waterwhite is preferred in many situations. Walnut and to a lesser extent maple are not instances where this is the case.

That said, as long as the finish has integrity (have you tested it for how easily it scratches and done an adhesion test?). These could be solved with a further toner coat or two if the finish has integrity. At least with what is in the photos. No reason to strip if the finish is not flaking off, doesn’t scratch easily, will not pull off with blue tape after doing a grid with a razor blade in the finish.

Check the edges to see if they have white haze or are they good/clear. Just hold the edge to a flat surface do they look different? If so that could be an indication of applying too many wet mils.

The photo is not the best, putting a toner over the existing finish would change the color, but the problem is it is already so dull- the wood is obscured, like a a dirty windshield.
Might as well use paint.

The piece shown to the left of the center problem child , is the control sample the finish shop coated a week before, because they messed up the PREVIOUS job. Not so badly, and on a lighter wood, so it was sort of acceptable, but because I could see it, I asked them to make sure it was not going to happen again.

I need a new career. Unfortunately we have some big orders already on the books. Gotta get them done somehow- this is so bad I am actually considering a hand rubbed oil finish on them.....

Pictures lie, but I think you're over reacting to the fix. It just lacks the color. Toner fixes this.

Was thinking last night, the other time I have seen this is when someone uses too much sealer and not enough topcoat. Sealers will give it the milky/cloudly look if more than one coat is used often. Some finishers attempt to save money if 3 coats are required by using 2 sealers and 1 topcoat instead of 1 sealer coat and 2 topcoats. I think this might be your issue if he is using conversion varnish.
Good luck

They are using the CV as a sealer.
I took two more photos, against two different pieces of sapele.
It looks like they finished the wood with milk. It looks dead. All the reflectivity is gone. Like they turned it into plastic laminate.

View higher quality, full size image (576 X 432)

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