Question
I have been finishing some oak and using CV. I am not sure what steps I am missing. After a seal coat I sanded everything with a 320 grit sanding pad. Last time I used CV I sprayed the finish coat only to find that there were white spots in the grain from the sanding dust. This time I tried to blow off the dust and use a paintbrush to help clear the open grain in the oak.
This was taking far too long and getting into the negative as far as profit, so I used mineral spirits, blew off and wiped down about 1700 ft of trim before shooting the finish coat at 3 to 4 mill thick. The finish turned out real nice, but I am there to make money for the company and there is something wrong with my method. I kind of like the CV but I have to get the speed up to what I can do with a pre-cat lacquer, or at least close.
Forum Responses
(Finishing Forum)
From contributor M:
How long did you let the sealer coat cure before topcoating? Maybe it cured too long and did not melt from the topcoat? I personally have never had that problem. I always used Duravar and KlearVar for years and never experienced what you are talking about. The only time I have ever seen that happen was when I used a Gemini CV. I also blow everything off really well with compressed air (about 150psi), and wipe everything down with a clean rag, then reblow it off before topping.
I'm sure the cabinetmakers blow off the raw wood dust leftover by sanding, otherwise the finish is going to end up being rough. You have to blow out the sealer sanding dust otherwise it will be locked in the grain by the conversion varnish. Unlike a lacquer, which will melt the dust, I have found that unless I remove most of the sealer powder when using a conversion varnish it will end up showing through the topcoat.
Show your employer the difference between the way you want to do it and the way they would like it done and let them make the decision.
On a side note, you may try to crank up the air pressure when you blow off the dust and if necessary, try a tac rag along with the compressed air.
I used at least 120-150 PSI to blow off the dust, but found it did not work well, then we used the mineral spirit wipe down. That worked, however it was time consuming. We haven't used much CV but I would like to know what I can do to cut time and cost.
If it still happens try changing your sanding technique. You may be sort of grinding the coating into the pores. Make sure you are using a no-fill type and don't repeatedly sand over the same area without blowing off the dust periodically.
If this and a thorough cleaning of the dust out of the grain is not profitable time wise in your situation, then CV may not be for you. I see a lot of shops who use CV for jobs that would be fine with pre-cat on them. You have to ask yourself if the CV is really warranted for what you are doing and if it is, you will have to find a way to either live with the time it takes to do correctly or find other ways to improve production time.
I am not sure when we will use CV again but I have to say as a finisher I love the hardness of it and if we can find a way to up the production speed I would like to use it more often. I had good luck with it this time wiping it down with spirits. The overall finish is up to our standards, however I will use what you all are suggesting and see how it can up the speed.
But for the purposes of finishing, it generally refers to nitrocellulose lacquer, which pretty much just means good old straight, non-catalyzed lacquer. Confusion comes when the chemical name is used as the slang term for lacquer. The actual chemical is used in other types of finishes as well. Pre-cats have some degree of nitro in them, some more than others, and even some post-cats have it.
The Duravar that contributor M mentions behaving much like nitro does so because it has nitrocellulose in it. This is why MLC got called out years ago for calling the product a conversion varnish and now refers to it as catalyzed lacquer. A true CV should have little to none in it.
