Troubleshooting a Conversion Varnish Table Finish
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Milky cast and unexpected damage — pros say too-thick application is the likely culprit. July 9, 2005
Question
We finished and delivered an oak conference table to a client four weeks ago. We used Antoni c/v with a satin sheen. I was at the client's today and the table looked completely different than when it was delivered. There are two faint heat marks from Styrofoam coffee cups as well as some light scuff marks. I am new to conversion varnish and thought this stuff was supposed to be durable. I let the table cure for 1 week before it was delivered. Is this too soon? It looked beautiful when it left; now it looks like it is 10 years old. What are my chances of stripping off the c/v? I would like to re-do the table with ML Campbell Duravar or some other post cat lacquer. I have done many conference tables in the past with post cat lacquer and never had this kind of problem. Any input on this matter is greatly appreciated.
Forum Responses
From contributor B:
What was the catalyst to resin ratio? Did you measure it precisely?
From contributor T:
Any chance less catalyst was added than there should have been? Drying temps were over 68 F? Did you add any retarder? 10 days is plenty of waiting.
From the original questioner:
The resin to catalyst ratio was 10-1, per Antoni's specs. The measurement was exact. We are based in northern Illinois, so it is cold here. I made sure the shop was 70 degrees for several hours after it was sprayed. No retarder was used. The finisher who sprayed it does tend to have a heavy hand when it comes to applying finish. Can this have anything to do with it?
From contributor T:
Could be too heavy of a sprayed coat in too cold of weather. A friend of mine had the same problem here in Florida when we were at 60F a few weeks ago. The film dries a lot longer, so when you spray the second coat, it lifts the first one because it hasn't fully adhered. In those temperatures I learned to watch my local weather and only spray one coat per day and let dry overnight.
From the original questioner:
Thanks for your input. I am picking up the table this afternoon to re-do. I will keep you posted.
From contributor O:
Perhaps you should have sprayed the table with polyester or polyurethane. Is it a full fill finish? Did your finisher use paste fill or try to fill the grain with the finish? This will be the deciding factor, because if he used more than 6 wet mils, he used too much. Perhaps you should get him to mill his finishes. If you don't and you're admitting to him having a heavy hand, then get ready for some finishing jobs to be returned to you for cracking. Is the finish milky? If so, then it surely is a mill problem. What are the chances of him using old finish from the prior shift or day before? This can also be the problem. Did the finisher properly catalyze the product?
From the original questioner:
Here is the latest update. I had my delivery crew pick up the table and bring it back to the shop (and yes, it did have a very faint milky cast to it). I was preparing for a nightmare of a time to strip and re-do. After applying the stripper, within 5 minutes the entire finish blistered and came off in sheets. So I am assuming the finish was applied too heavy. Any other ideas? I would like to prevent this from ever happening again. As we all know, do-overs are costly.
From contributor O:
It's good to hear that you stripped the table. The first thing I would do is get your finisher a mill gauge and explain how to use it. The next thing is to have him spray a piece of scrap at the end of his shift when he is tired and less focused. Mill it out yourself and if he's over, then perhaps your fluid tip is too large and is letting out too much finish for this finisher. If so, go to the next size smaller or tell him to move the head of the gun further away with quicker hand speed. We have all been down this road and this is how I handle the situation in my shop.
From contributor B:
I would use what you're used to. Duravar is not bad, in fact, for what it is. It's a good, durable coating. Not the best, but good. Don't introduce something new on a piece like this. Actually, with it coming up in strips like that, it smacks to me of poor adhesion as well. Something you did between bare wood and your heavy top coats may be the real culprit.
