Discoloration
12/20/16
Okay, I'm in a bit of a pinch. I just received a call from my contractor on a project we completed just over a year ago. He sent some pics over (attached) showing several walnut panels with discoloration along the bottom edge. This is clear walnut (no stain) with a coat of vinyl sealer, scuff sand, and two top coats of Chemcraft pre-cat Varicure lacquer. I've used this stuff for years with beautiful, excellent wear results. It's been a proven winner for us. Can anyone tell me what is going on here? Why is it only on a few panels and not the others? Does this look like moisture or chemical invasion? Is this a partial finish failure (which seems like an oxymoron)? Bad batch? Maybe the finish was slightly too old (I keep good tabs on this). Obviously, I am out to take care of my clients but if this is improper care of the cabinetry, I need to be aware of that too. I saw this one other time when we were using a different lacquer product. Same thing - just a few panels discolored mostly along the bottom edge. There may be a whole different approach to this as well. Both jobs were flat vertical grain veneer doors matched to each other and edge banded all four sides. Could it be that the finish has nothing to do with it at all as in maybe the edge banding glue did not completely coat the edge which could have left minute gaps for moisture to enter and wick up through capillary action since all the grain runs vertically? Or, maybe whatever cleaner they are using is eating just enough of the glue line to get through to the veneer? I'm looking for answers - any help would be greatly appreciated! Have any of you guys seen anything like this before?
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12/20/16 #2: Discoloration ...
My guess would be that whoever is doing the vacuuming is also attempting to aggressively vacuum the very bottom of those panels causing chips.
12/20/16 #3: Discoloration ...
looks like moisture damage to me.... aggressive cleaners and mopping that area could be the problem cause it looks to be a tile floor correct?
12/20/16 #4: Discoloration ...
Looks like the bottom of your panels/doors weren't sealed well enough and the water is wicking up. Any water will run down the panel/door/drawer and bead up on the bottom edge. If not sealed well you get a situation like yours. Also it looks like your edges are very sharp. This is another possible area where water could wick up through a weak link.
my2cts
good luck
12/20/16 #5: Discoloration ...
Yes, this is a tile floor - so it could possibly be a mop or vacuum introducing moisture or rubbing along the bottom edge in a way that compromises the finish. With the way it has bleached the walnut, would moisture do this or does this look more like chemical reaction? Also, if this is moisture, would it take a lot of water to have this effect or could the finish have been compromised on the bottom edge and over time allowed moisture from the surrounding air to wick up? Thanks for the feedback!
12/20/16 #6: Discoloration ...
Thanks, Bart! We do hand ease all of the edges to avoid the sharp corners as I know that is where a lot of finish issues happen. Also, we spray a nice wet coat of vinyl seal before any topcoats on all faces and edges evenly so I wouldn't think it would be a sealing issue although we are revisiting our whole process to make sure we aren't missing anything.
12/20/16 #7: Discoloration ...
Picture #2 looks like white dot on wood floor. Maybe cleaners are using a chemical cleaner that they shouldn't be using.
12/20/16 #8: Discoloration ...
How many total coats front and back to you do? I do 6 total 4 front 2 back. So the edges get 6 coats. I just use 400gt down the middle of the edge then synthetic steel wool to wrap the edge to leave as much finish on the edge as possible. I'm doing some 1/4 sawn white slab doors at the moment.
I did have an issue once years ago on some slab doors that mirrors what you have. That was back in the day when I sprayed vertical. If they are hitting the cabs with mop/vacuum it could damage the edge enough for moisture to invade. It doesn't take much.
12/20/16 #9: Discoloration ...
Thanks, Bart! Okay, the edges get coated at least once with vinyl sealer like everything else. Then, coated two to three times with top coat. I use 220 to scuff sand the edges with scotch brite for the corners before top coating to avoid burning through. Everything is sprayed flat for a good wet coat.
12/20/16 #10: Discoloration ...
220 sounds heavy to me. Especially since you're using solvent which doesn't raise the grain. I use WB stains/finish which does raise the grain and only use 400. With only 3-4 total coats and using 220 I'd say you're not leaving much finish on the edges.
my2cts
12/20/16 #11: Discoloration ...
I'd say the moisture is under the finish, not a bleached walnut panel. I stopped using precat a long time ago, not nearly as tough or water resistant as they tell you in the sales literature. I also think the finish looks a little thin for what appears to be a commercial application. Do you thin the precat? What is your wet coat film thickness?
12/21/16 #12: Discoloration ...
Thanks, Bart and Rich for your input! Finer grit for the edges is definitely not a bad idea. I do not thin the precat at all - just spray right out of the bucket which is what they recommend. I'm thinking we are getting right around 5 wet mils per coat when we took measurements. I spray one topcoat, wait a few minutes and then spray the second 90 degrees to the first. The thing that baffles me is just having it on a few panels. I could take you to so many projects that we have used this on and they still look like they just came hot off the press.
12/21/16 #13: Discoloration ...
Is that a heat register in the toe kick? Think you got some wood movement to crack the finish? Doesn't sound like you are applying to factory specs. Sounds like you are almost getting one 10 mil wet coat if you only wait a few minutes and don't sand between coats. I'd say that caused the finish to crack, and then somehow water of some chemical got in the cracks.
"Apply at 3 – 5 mill wet on sanded substrate. Further coats may be applied after complete drying followed by sanding with 280/320 grit stearated paper. The second and subsequent coats must be applied the same day as the previous coat is sanded. The maximum film build of Varicure 275 should not exceed 4 mils dry."
Chemcraft document
12/22/16 #14: Discoloration ...
looks to me like a classic case of pre-cat pulling away from the substrate do to repeted substrate swelling and shrinking because of water penetration at the edge banding/ plywood interface. I do quite a few refinish jobs and this a common occurance esp. with pre-cat lacquer; it's too inflexible to handle much movement and not moisture resistant enough to keep water from penetrating at weak spots. Once it starts it's downward spiral..
The fix if your lucky and things blend-in is to sand back the affected areas and recoat. If your not lucky and and the affected area color won't come back try washing the affected areas with oxalic acid, rinsing and let dry well before sanding. This should take the water stains out. If this doesn't blend in...you'll have to strip off the finish and start over.
12/22/16 #15: Discoloration ...
Are those plywood panels? If so I doubt if you can seal the edges enough if they are using a sopping wet mop and getting the panels wet on the edge. I would coat those edges with 2 part West Systems epoxy and that should solve future problems.
12/22/16 #16: Discoloration ...
One more thing to consider; was this a fresh batch of finish or had it been hanging around the shop or dealer for awhile? It does go bad after awhile. the pre-cat I use once every year or two has a 6 month shelve life.
12/24/16 #17: Discoloration ...
i had a Kraftmaid repair guy tell me once that they were seeing finish failure on the bottom of some cabinets due to people using those floor steam cleaners on there tile floors.
nicko
12/25/16 #18: Discoloration ...
You have a HVAC register where the problem is. There will be constant temperture change at that point causing expansion/contraction. Block or move register.
12/28/16 #19: Discoloration ...
Thanks everyone for your input! We are considering all this and more. I'm actually having a chemcraft rep come out to help me analyze the issue. Since I've never seen this before, we are taking it very seriously even to the point of having him watch us spray and see if we are out of spec in any way. (Double coating within a few minutes was actually recommended by the supplier).The finish also was not beyond the 6 month shelf life. I will not be sitting around worrying about who I might get a call from next saying their finish is failing. Although this has been the only exception and not the norm, one call back is not acceptable to me. I am also very seriously considering changing finishes although I'm not sure where to start. When you get dialed into a system that has worked so well, it is hard to change.
1/4/17 #20: Discoloration ...
Agree with everyone that you have moisture wicking up from the floor. Not sure if you can ever seal those ends with your finish. Remember that if you are shooting a vertical surface vs. a horizontal one, you will get about 2/3 less finish due to gravity. We either paint those edges or apply a glue wash. Chemcraft makes Vericure touch up spray can. Clean the surface and try spraying on a few coats and it should emulsify. If that works you may want to run over the edges with a block of paraffin to post seal them.