Conversion varnish application advice
Techniques for applying ML Campbell conversion varnish. March 20, 2001
Q.
I would like advice on application of ML Campbell paints, specifically the white conversion varnish.
Forum Responses
You will have to reduce ML Campbell's conversion varnish. We don't have to with Sherwin Williams or Guardsman (Lilly).
The resistant paint is great--use their Clawlock as a primer. You do need the proper equipment. Once you have enough build with primer, you will not need multiple coats of resistant. What's wrong with thinning?
I use an ML Campbell pre-cat lacquer, Magnalac. With this product you don't need separate sealers. It is it's own sealer. Spray one coat, let dry, scuff sand (220 grit works best), spray final coat. It dries fast and has superior chip resistance, water resistance and chemical resistance. It does not need any reducing.
Be careful of the new ML Campbell Woodsong II 20 based stains. I have found, through testing and customer complaints, it takes up to three weeks for the finish to cure properly. It's fragile and very easily damaged. No fault of the coating, but the stain. ML Campbell solved my problem by remixing the standard colors and my custom colors in WS2B10. This is a faster drying stain, which can also hold more pigment. Works great!
They produce excellent post-cat products with low VOCs. If sprayed through an air-assisted airless system or HVLP pressure pot system with the right tip and pressure, you should not need reduction. However, I like it for flow out.
We used ML Campbell finishes and Woodsong 2 stain for six months. It's a nice stain, but finish doesn't like to bond to it. You shouldn't sand your products past 120 and should do some bond tests. You can also wet the wood with a mist coat of 1 part alcohol, 1 part water, prior to staining.
ML Campbell claims that the problem is not with the stain but with the way it is being applied. I did notice on the can it says "hot spray not recommended." I use a conventional spray gun and have never had a problem. Are those of you having the problems using HVLPs?
I am not having problems. I never use anything but Duravar and I reduce it with mid temp acrylic enamel reducer, which is mostly alcohol. For every 10 ounces of Duravar, use 2 ounces of acrylic enamel reducer, 1ounce of catalyst. Always dust coat first, then 2 full 5 mil coats. The flow out is incredibly good.
I too use Durovar for pretty much everything I do. The testing I did for Woodsong II S&W (20 base) failed in every example. I applied the stain by conventional spray and wipe and some by hand and allowed different dry times for each set. I HVLP and conventional sprayed various measured wet mils using Durovar, Krystal and Magnamax. Some with sealers before topcoat, some reduced with C160 thinner, some not reduced at all. I also did the same for the old Woodsong S&W stains and another company's stain. These were all done on various species, both solids and veneers (moisture tested) and prepped with ceramic papers. I spent a lot of time with this stuff, covering every angle I could. The bond testing went on over a period of a month in a controlled environment. My 100 grit final prepped pieces held up no better than the 180 final prepped. The old Woodsong and the competition's held up perfect in all samples. The Woodsong II S&W samples took up to three weeks to cure. Only then did the finishes bond properly.
The regional rep says this stuff was developed for all the people complaining that the original Woodsong had too small a working window before it dried. I went to the Woodsong II 10 base stain and have had no problems since. I tested the 10 base as well and they all passed. I suggest you do some testing of your own and see what works.
