Rubbing Out Nitro Cell Lacquer
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Is there a speedy way to polish a high-gloss finish? December 9, 2004
Question
I'm trying to find a more efficient way to rub or polish table tops. I've always hand-sanded, graduating from 400, 600, 800, 1000, 1200, 1500, 2000. Needless to say, this is a lot of time and effort, not to mention chasing scratches. On this particular table, I've used MLC high build gloss. (I know other coatings build better, but I needed the look). Two main questions: Can I use 3M 260L sanding discs on my random orbital? (I tried a small area with p1000 and it left sanding marks) and can "burn through" from polishing be corrected without respraying the whole table? Any other advice is welcome.
Forum Responses
(Finishing Forum)
From contributor D:
260L is great paper, but it is designed to work dry only on hard coatings such as 2K acrylic urethane (automotive clearcoat) for which it was designed, and if you want to use it on lacquer, you need to use it wet, since if you use it dry, it will immediately start to corn up and scratch. This doesn't happen if you use a spritzer bottle with water and some Dawn dishwashing soap in it to lubricate the paper. Spray this mixture on the paper first and then on the work and after you’ve made a slurry after sanding for awhile, squeegee this off and use fresh water/soap mixture. It's advisable to use an air powered sander when doing this, since electrocution has been known to hurt.
From the original questioner:
Thanks. I did use it wet when testing with the 1000g using Murphy's Oil Soap and water, but I almost immediately got the dreaded little sanding circles. Is the finish not hard enough? It had sat for 3 days, but I am in the mid south and have to go a little heavy on the retarder.
From contributor D:
Then you're screwed. Humidity, retarder and lacquer mean perpetual softness, so it's back to the bucket for you, my friend. Viagra will not make that lacquer hard.
From the original questioner:
Thanks again. It's not what I wanted to hear, but at least I'll quit wasting my time.
From contributor M:
Wet sand is the way to go. Use an air-powered jitterbug straight line sander. This way all your sanding marks are one direction, not swirls. Haven't done it in years, but we used to wet sand from 400 through 1500, then buff. When we did this system, it saved tons and tons of man hours. 400 against the grain, then 600 with the grain. When the cross scratches were gone, you knew you had taken out all the marks from 400 grit. Then we used a vertical buffing wheel and 3 grits of rouge from Seagraves to buff out the rest. We found the rouge easier and faster to work with on vertical polisher than conventional polishes on pads.
Use a slower flash solvent and lower the retarder level to its absolute minimum. Since you will be sanding and buffing, it doesn't need to be perfect. You need to find the happy medium of dry times and surfaces that don't need too much work to look good.
I almost forgot - the two most important ingredients when sanding and buffing large projects for days and days on end... a loud radio and ice cold beer.
From the original questioner:
Contributor M, can you recommend a brand of straight line sander? I'll try to figure out the beer myself, unless one is more compatible with wet sanding.
From contributor S:
On your existing finished surface, you will want to get rid of the slow solvents which still may be in your lacquer. The way to do that is to help them gas off by running a fan across their surfaces and venting that air out of the building or room.
Circulating air is an important issue with evaporative finishes. Run that air and eventually your finish will complete its cure cycle. Eventually, the solvents will gas off. Running the air helps this process.
From the original questioner:
The fan is blowing. Hopefully I can avoid "getting out the bucket."
From contributor M:
This is a number of years back and the memory is a little foggy, but I believe we used all Snap-On ones. They were awesome, but a little pricey. The service was key, though. If you ever needed one serviced, the rep would leave another to use while it was out. Not that they were breaking down all the time, but we did tons and tons of high gloss mirror finishes at that shop. Sometimes we would go for weeks at a time just on sanding and buffing 12-16 hours a day, six days a week. It's amazing how many hours you will work in your young 20's when the boss pays cash and buys the beer.
I am sure there are other suppliers - I am just not familiar with them. Maybe another thread on straight line pneumatic wet sanders will get you more options.
