Troubleshooting Wrinkling in Pigmented Varnish

      In jobs involving multiple coats and sanding between coats, pigmented conversion varnish can sometimes have a wrinkling or crinkling problem. Here, finishers try to figure out what can go wrong, and how to stop it. September 10, 2007

From time to time I get crackling in ML Campbell Resistant paint. Does anyone know why that happens?

Forum Responses
(Finishing Forum)
From contributor L:
You are putting it on too thick. It has a 4-5 mil dry film thickness limit.

From contributor P:
How long after spraying does it crackle? Any chance you're over-catalyzing? Too many coats/too thick?

From the original questioner:
I put on two coats of primer, then one coat of Resistant. All looks good... but let's double check the color. Oh sh*t! They mixed the wrong color even though the label had the right color on it. Sanded and recoated, and now there's crackling paint.

From contributor L:
Sounds like a thickness problem to me.

From contributor P:
It usually takes some time for CV to cure and crack from thickness or catalyzing errors. Sounds more like the problem is crinkling/wrinkling rather than crazing/cracking. Say that 5 times fast...

From contributor B:
I've had the same problem. I found that you have to recoat as soon as it's sandable (20 minutes or so) or wait until it's cured. Any time in between you have a chance of crinkling. (I hate that.)

From the original questioner:
Cure time? It was two days before they fixed the color problem. What is the cure time anyway?

From contributor R:
What kind of primer? It should have been Clawlock.

From contributor B:
I just painted some kitchen cabinet doors that I primed with Clawlock and painted the next day. The Clawlock crinkled on me. I had to sand it out and give another coat while praying it would not crinkle again. I used BIN primer on my next job, with Resistant, and had no problems.

From contributor D:
The most likely cause of your crackling is that you sanded through a finish coat. This causes your next coat to wrinkle the undercoat. When you sand through a finish coat, you must lay down a coating of vinyl sealer as a barrier coat. You can spot spray the vinyl sealer in cases where you might spot sand and cut through the finish.

From what you wrote, you did not over catalyze, you did not lay down a coating too thick. You did, however, sand through your coat. It says in the tech sheet that this sanding through the finish coat is to be avoided. So, now I have detailed for you a workaround.

Your vinyl coat layer does not have to be thick. Your overall coating thickness still has to be 4 - 5 dry mils, even with the vinyl sealer application. If vinyl sealer were part of your finish schedule - and in this case it isn't until you introduce the workaround step - then you must keep the vinyl sealer to under 1/5 dry mil. I'm just including this information because I want to touch on all the bases.

From the original questioner:
Thanks for all the responses. I just don't know about this Resistant paint. I use a Kremlin and gravity feed cup guns for painting - average year I go through 150 gal of material. I have been using most of their products, but this paint has been problematic for me. Will spray a few jobs and they come out great. Then something like this happens.

I'm going to re-sand, shoot a coat of sealer, and start over.

From the original questioner:
Sealer is showing signs of crackle. Called tech support. They say there are too many coats of paint. My response, bullsh*t! I have in the past given a door several coats of paint due to a comedy of errors. I have to wonder if it's not the paint?

From contributor R:
Not having enough catalyst will also cause a crackle.

From the original questioner:
What is the catalyst tolerance (+ or - what percent)? I measure the catalyst in ml. using a graduated cylinder when using same amounts for a cup gun.

From contributor R:
Resistant needs to be catalyzed 10%. Don't know what you can get away with, but I do know (don't ask) half as much won't work. I've also noticed you won't have recoat problems if you spray as packaged. No thinners or retarders. That means using pressure pots or pumps. By the way, did you use Clawlock?

From contributor D:
How accurate does your 10% measurement have to be? If you start using cc's as your measurement (1oz = 30 cc's), then you will be accurate enough. If you are measuring less than 1/4 oz (7.5 cc's), then you should be using a syringe for the catalyst so that your ratios are preserved to a reasonable amount. Other than that, the one ounce graduated "shot glass" type cup should be sufficient.

From the original questioner:
Contributor R, I think you may have figured it out for me. My dealer claims you can use Magnaclaw or Clawlock as a primer. Magnaclaw seems to work okay, but if you need to recoat the Resistant, you need to sand. And if you go through the Resistant to the primer, this is what may be causing the problem. Now I'm switching to Clawlock all the time. I also have found I need to reduce Resistant about 20% to get a perfect finish. I use the retarder to do so. Also I'm spraying with a Kremlin Airmax MVX.

From contributor R:
Check the PI sheet on Campbell's web site. Twenty percent retarder is a bit too much. Consider tweaking your Kremlin to reduce the solvents. You'll be glad you did.

From the original questioner:
It takes about 20% thinner or retarder to get the paint to go through the ford cup in the proper time. I know the sheet says 10%, but I think that's to meet the VOC laws in a few states. I have had trouble before without thinning. Also, maybe it depends on the amount of pigment that's in the paint?

From contributor L:
You should be able to spray mud with a Kremlin. I thin my Resistant 20% when I use my Gravity Feed HVLP.

From contributor R:
A paint rep once told me, "If you don't do it our way, don't complain about what you get." I've been going by the spec sheets ever since. Think about the recoat window with all that retarder. Tweak that Kremlin. Five percent retarder at the most.

From contributor O:
The following is a finish schedule that I've been using in any season with any humidity. Spray Clawlock primer with a #6 -154 out of a Kremlin pump set at pump pressure 52lbs and air at 22lbs. Don't thin; add catalyst at 10%. Spray a box coat, then let flash for 10 minutes. Spray a second box coat and let product dry overnight. Sand with 320 grit paper and clean for top coat. Spray Resistant catalyzed at 10% with #2 flow enhancer at 10%. Use a #6-154 set at pump pressure 52lbs and air pressure at 22lbs. Spray a box coat and let flash for 10 minutes and spray a second box coat, then let dry overnight. This is the way I spray this system and I've had lots of the top guys from Campbell use this finish schedule.

From contributor G:
Dry overnight twice? Ready to use on the third day? Sounds slow...

From contributor O:
This schedule may be slow, but it works well! I sand and spray all of my own product. I have no problem producing work by taking advantage of drying times.

Example: I started a stain and glazed kitchen last Friday. I will have between 60 and 65 hours when complete and it will be done on Wednesday. It includes white wood sanding, spray stain, sealer, sealer sanding, glaze, vinyl, scuff vinyl, and top coat. This includes glaze on both sides of doors.

Day 1 is whitewood sand on all pieces, stain and sealer on 1 side of all 2 sided pieces. Day 2 is stain and sealer on all cabinets + molding + 2nd side of all 2 sided pieces. Day 3 glaze and vinyl 1 side of all 2 sided pieces + glaze and vinyl on cabinets + molding. Day 4 glaze and vinyl 2nd side of 2 sided pieces and top coat all cabinets + molding. Day 5 is top coat backs of doors and drawers in the am and top coat fronts in the pm.

This kitchen is 1026 sq. ft. of stain and glaze with an average of 200 ft or more a day. Some days are 12 hours or more and that's how I produce this. Is this slow for a one man shop doing stain and glaze? On a monthly basis this would be around 5000 sq. feet of production at a price of say $15.00 a foot. This would be $ 75,000 a month. Is this a little slow? My coatings are always dry, no crinkle, no crackle, no redos, no resprays, no delays, just let things dry. Remember, it's not what you do during the day that counts, it's what's happening at night while you're resting.

From contributor G:
Sounded slow for primer and topcoat - not slow for stain and glaze.

From the original questioner:
Contributor O, thanks for your response. I have never had any trouble with ML stains, glazes, clear coats and Magnamax paint. Only with Resistant paints - I'm not sure why. I just finished a job where I sprayed all the doors and they came out perfect. A week later I sprayed the end panels and open shelves, and in several different places I had that crinkle effect.

I try to have a spray motion that is like a machine, so I don't think it's a paint thickness issue. Could it be product contamination? Something suspended in the paint? Could I be contaminating it somehow? Like I said, this only happens when I spray Resistant. This just baffles me.

From contributor O:
Everyone thinks you need to load a panel with primer to have a build to sand. This is true to a certain point! Some spray primer with a #12 -154 tip in a box coat pattern. This is always wet when you try to sand because of the film thickness that needs to dry. Try this on your next paint job. Spray uncut Clawlock catalyzed at 10%. The tip you're going to use is a #6-154. Your pump pressure will be 52 lbs and your air will be 22lbs. Spray a box coat and let flash off.

Example: If I have a rack of doors and drawers, I will spray the entire rack with a box coat. When I'm done I return to the first door that was sprayed and spray a second box coat. These will surely powder when sanded the following day. By spraying wet on wet, you're letting the bottom coat semi-cure or exhale under much less mill thickness. This is why you can get the build and a fully cured product to sand. If you dump and run, it's harder for the coating to exhale under so much mill thickness. You will also notice especially if you're spraying poplar that the primer is not as opaque and covers more. Lots of people just blow and go and the reason they're getting crinkling is because the primer was dumped on and is not fully cured due to what I described above. Apply the Resistant the same way and you'll notice the opaqueness will also disappear from your top coat.

From contributor O:
The next time you have to do a recoat over Resistant, try this. Sand and scuff all product. Spray with water white vinyl 1 pass catalyzed at 1%. Let dry overnight and scuff the next day. Apply Resistant at a normal mill thickness. This will eliminate any problem if you need to respray. If you're worried about crinkle before you spray Resistant, this will insure success.

From contributor O:
This is my finishing schedule for paint and glaze. Day 1 whitewood sand all cabinets, doors, drawers, and molding. Spray all 2 sided parts with primer on 1 side. Spray all cabinets and molding with primer. 6.5 hours for sanding and 3 hours for spraying primer. Day 2 spray 2nd side of all 2 sided parts. Sand cabinets and molding. 1 hour for spraying primer, 4.5 hours for primer sanding, and 3 hours for top coat on cabinets. Day 3 sand all 2 sided pieces and spray 1 side top coat. Scuff and glaze all cabinets and molding. Vinyl all cabinets. Spray 1 side of doors 1.5 hours. Sanding primed doors 4.5 hours. Scuff, glaze, and vinyl 5.5 hours. Day 4 scuff all cabinets and top coat. Topcoat 2nd side of doors. 3 hours for cabinets and 1.5 for top coat on the doors. Scuff and top coat molding 1 hour. Day 5 glaze and vinyl 1 side of doors. Glaze and vinyl 2nd side of doors 9 hours. Day 6 scuff and top coat 1 side in the am and 2 side in the pm. 10 hours to include drying time. Without drying time would be 2 hours in the am and 2 hours in the pm. The other 6 hours would be whitewood sanding on the next job. Total on the job would be 54 hours over 5 days. I don't know if this is fast, but I very rarely have a customer complain that things take too long and that includes polyester and polyurethane high gloss wet look finishes.

From contributor G:
I am more accustomed to a high production shop environment where only finishing one kitchen in a day is considered slow. If your customers like what you do, there is no problem.

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