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  1. #1
    Returning Member rolly1's Avatar
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    Buffing out a varnish finish

    Has anyone used an buffing machine and auto polishing compound to get the dust nibs out of a varnish finish? If so could you explain the technique you used. example: Did you use water to keep the polish from drying before you got everything smoothed out.
    Alan Brackett

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    Re: Buffing out a varnish finish

    First question is what varnish are yo using? Many varnishes and almost all polyurethane vanishes are fairly soft and do not rub out to a high gloss. Poly is added to varnish to resist scratching and rubbing out is scratching.

    Interior, non-poly varnishes can sometimes be rubbed to a high gloss but the finish must be fully cured. Oil based varnish takes 3-4 weeks to fully cure. Let your nose be your guide--as long as it is emitting an odor, it is still curing.

    The process I use for hard varnishes is to first level the surface with 400 W&D paper using mineral oil thinned with mineral spirits. Water with very little dishwashing liquid will work well too. Sand lightly just to get it flat. Then move on to 600 W&D, then 1200 W&D. I then move to white polishing compound applied with a power buffer on low speed. Be careful or the finish will get hot and melt. At this point you should have a pretty good sheen. Finish it off by machine applying an automotive swirl remover and then buff.

    Be very careful of sand through and buff through particularly near edges. Also, be sure you have enough film thickness of your finish. You will be removing quite a bit of material.

    Personally, I rarely go through the process. Piano type finishes are not my taste for most furniture. Mostly I go for a satin sheen which is easier to achieve.

    The best way to remove dust nibs is not to get them in the first place. This involves either a finishing room or really cleaning the finishing space before applying the finish. What I do is get real finicky with my final coat. I lightly sand the prior coat with 320 paper to remove any nibs. Then I vacuum off the dust. I get my finishing stuff out and ready and then get out of the area for a couple of hours letting my air cleaner run. Now change clothes (much dust that ends up on a finish comes out of dusty clothes) and carefully go back into the finishing area. Wipe down the item with a rag lightly dampened in mineral spirits and carefully lay on the final coat. Get out of the room again for a couple of hours.

    Another trick is to put a cover over the finished item to catch any dust in the air. Put some supports around the item and then put a piece of plywood or hardboard over the finished item. Just be sure you have vacuumed off the cover and supports when vacuuming the item. Wipe the cover with your mineral spirits dampened rag.

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    Returning Member rolly1's Avatar
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    Re: Buffing out a varnish finish

    Thanks for the information. I am using Behlens Rockhard Table Varnish. It says to allow 72 to 96 hours before rubbing. I have already leveled the finish using 320 sandpaper. I plan to use 600 wet/dry sandpaper and soapy water next. Before I applied the finish I cleaned the shop and wet down the floor. I do not have a air filtration system at this time. Do you have any recommendations for a 20 X 20 foot area?
    Alan Brackett

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    Returning Member DavidF's Avatar
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    Re: Buffing out a varnish finish

    Nice reply Howard. You mention your "satin sheen" what is your finishing stratagy for that?
    David
    "There is no trouble so great or grave that cannot be much diminished by a nice cup of tea" Bernard-Paul Heroux

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    Re: Buffing out a varnish finish

    Alan,

    I once made a small walnut oval topped table and finished it with Behlens Rockhard Table Varnish. It is an alkyd short-oil varnish and buffs out fairly well. Much better than a typical polyurethane varnish, as Howard mentions. I brushed on several coats of the varnish, sanding lightly between coats, and put a cover over the top to keep dust from landing on it. It worked pretty well although small nibs will be cut off during the sanding/buffing process. Since a fair amount of finish will be removed during sanding, you should make sure that the last coat is relatively thick. Otherwise, you might sand through the top layer to reveal inter-layer witness lines. If you do, about the only solution that I found to work was to apply another coat of varnish. This is one disadvantage of using a liquid (like water) as a sanding lubricant - it hides the fact that you have sanded through the top layer. Unfortunately, I learned this lesson three times! Dry sanding is messier and uses more sandpaper but it is easier to see where you are. I waited more than three weeks before starting the sanding/buffing process. The harder the varnish, the easier it will be to achieve a high gloss finish. Get the top layer as flat as possible, going through at least 600 grit paper, before starting buffing. I used a buffer as you are with auto polishing and buffing compounds. Howard warns against staying in one spot too long to keep from melting the finish. Good advice! If you melt an area it is a royal pain in the *** to sand it out - all the while getting closer to a possible sand-through of the top layer. I would also advise you to always hold the buffer so that the buffing pad is moving OFF of the edge and do not apply too much pressure near the edge. Do not have it rotating INTO the edge or it will be difficult to not buff through the finish on the edge, where it is the thinnest. This was a great learning experience (taking about four months for the finish work alone!) and the table turned out really nice. Hope yours tuns out as well - good luck.

    Dave

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    Returning Member rolly1's Avatar
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    Re: Buffing out a varnish finish

    This has been a learning experience for me as well. I have been working on this finish for about a month. At one point I had the previous layer of finish turn lose when I applied the last coat and had to sand it a lot of it off and then build the finish again.
    Thanks for the help.
    Alan Brackett

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    Re: Buffing out a varnish finish

    Quote Originally Posted by DavidF
    Nice reply Howard. You mention your "satin sheen" what is your finishing stratagy for that?
    Just stop at the 600 grit and apply a coat of paste wax using white scotchbrite material. Apply the wax rubbing in the direction of the grain. Let it dry and buff. Wax doesn't "build" so only apply a single coat or it tends to get gummy.

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    Re: Buffing out a varnish finish

    I use my DeWalt DW420 ROS (actually its now a DW421 now as I installed the vacuum shroud) with a Hook & Loop pad with a piece of terry cloth under it to apply the polishing compound and have not had the problem of heat buildup.
    Also, if the white compound is not scratch-free enough, the auto stores like CarQuest also sell micro-finishing compound which they use on auto clear coats, which are no harder than poly. They recommend letting it cure for 2 - 4 weeks before polishing it out tho. They also wet sand to the 2000 - 4000 g before using it. You may want to talk to the "Paint expert" at the auto store for polishing tips and techniques. Going though the clear coat leaves the same effect as going through the final varnish coat.
    Just a thought on where to get some ideas.:lol:
    Practicing at practical woodworking

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