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07-23-2010 07:40 PM
I'm using 0000 Steel Wool in between coats of oil poly, but I wonder if wet sandpaper would be more appropriate to get a more level finish? Rubbing out a run or high spot with steel wool seems to cause a uneven area. If so what grit(s) should I use? Also, would I use water or mineral spirit, the later of which would actually dissolve the finish.
If wet sandpaper is not used in situations like this, when is it required?
07-23-2010 09:13 PM
Steel wool, including the synthetic kind does not level finishes used between coats of finish. The real kind also can leave shards of steel to rust down the road. Sand paper is much better. BUT, there is no reason for sandpaper to be used wet. 315 grit is about the right. New finishes aren't as water resistant as they will be in a few weeks, and although mineral spirits will not dissolve a finish cured enough to be sanded, it still isn't a good idea, if for no other reason that it makes it hard to see how your sanding process is proceeding.
07-24-2010 03:39 AM
I completely agree with Amatuer. Steel wool is okay for a final buffing or to cut down a gloss finish, but 320 grit paper is what I use between coats.
07-24-2010 04:14 AM
…in all finishing steps, with the possible exception of “finishing the finish” as already mentioned. Remember, no finish is totally moisture proof, with some less resistant to moisture (water-vapor) than others. Moisture and shards of steel wool left behind in your finish (and you will leave some behind) do not produce a good combination.
Jim Kull, the former host of this forum used to relate the story of a maple bedroom suite that his shop refinished (twice) for a customer. One employee decided to use steel wool during the finishing process in much the same way that you have described. Several months after the completed job was delivered to the customer Jim received a call from the owner complaining about all the “freckles” in the finish. In the humid conditions the little amount of water-vapor migrating through the finish came into contact with the steel shards and, predictably, rust spots were the result.
A simple light sanding with 320P open-coat sandpaper (use a backer block on flat surfaces) is all that is required. Wipe the sanding dust away with a shop towel lightly dampened with mineral spirits/paint thinner before applying the next coat…
07-24-2010 06:20 AM
I don't know where I got the misconception that steel wool was used in between coats. Also, I though wet/dry sandpaper was always required with finishes. Guess I was wrong.
07-24-2010 08:00 AM - edited 07-25-2010 08:56 AM
It's not just using sandpaper between coats, you have to use it correctly to get and maintain a flat surface during the finish process. The key is to mount the sandpaper on a padded flat sanding block. You can make one up by gluing felt on the surface of a 3 3/8" wide flat piece of hard wood. Always sand with the grain.
As others have said, using any flexible media will not flatten a surface or keep it flat. Avoid flexible media except for non-flat surfaces Use non-woven abrasive media (Scotchbrite).
07-26-2010 01:10 PM
To affirm the info already stated...
Here's my 2 cents...
I say never use steel wool between coats.
Reason #1 you will leave shards of steel wool behind; then you will top coat it. Now you have steel wool IN your finish when water vapor get to it, and it will, it will RUST - IN YOUR FINISH.
Reason #2 Many steel wool products have oil to keep them from rusting so now you have oil on your surface... bad idea.
Reason #3 Poly does not stick well to itself or anything else for that matter that is why they tell you to sand between coats. Steel wool abrades the finish; it does not give enough "tooth" for poly to adhere well. 220 sand paper 320 at the finest.
There are other varnishes that are harder and better than poly for furniture; poly should be used on floors, period.
Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.
07-29-2010 05:51 AM
I for one do not use steel wool in any finishing process nor do I use water in the sanding process! Water, anywhere close to machine holes, pups, or screw holes and your asking for trouble. Like mentioned, there are sandpaper alternatives that produce far better results.