Hi, after waiting four week for the poly to cure, I just finished rubbing out the finish, then used rubbing compound and then polish. It looks great except I just now noticed a couple of small spots where I actually rubbed through the poly when I was rubbing ot the finish. Is there a way to do a spot repair on the finish (e.g., sand, then re-apply poly to the two spots that got rubbed through)? Or some other way to get those spots to shine/match the rest of the top? I am hoping i do not have to resand the whole thing and start from scratch. Thanks.
HELP with dull spots in rubbed out poly finish
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If you are sure you have rubbed through the finish to wood then you would need to clean the surface off with a wax and grease remover and put some more poly on. I wouldn't try to work just the spot but the entire area. It will need to be scuff sanded but I wouldn't sand the spot any more that was sanded through. Sometimes though you can sand through a layer of finish and have a spot with a different sheen. If that is the case you might be able to use rubbing compound more and fix it. When you were rubbing out the finish what grit sandpaper did you use? A grit no coarser than 1500 should be used for rubbing out a finish.
For a wax and grease remover I use Dupont Prepsol Solvent available at places that sell automotive paints.
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Did you stain, or in any other way change the woods natural color? (Other than the application of the poly)
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Is the "poly" an oil base or water base? How did you apply it? How many applications did you apply?
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Thanks for the responses. I just tried re-rubbing with the compound and I am not getting any shine so I am pretty sure I have rubbed through to the wood. When I originally started rubbing it out yesterday I used 600, 800, 1000, 1200, then 1500. I had six coats of poly on the wood and no stain.
Thanks. No stain was used, just the poly.
Six coats of oil-based poly wiped on.Is the "poly" an oil base or water base? How did you apply it? How many applications did you apply?
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With wipe on poly it takes two to three coats to equal one coat of brush on so effectively you may only have two or three real coats. If you are going to use 600 grit paper it would be better to do a little at a time between coats rather than apply the finish and start sanding. Without a electric buffer it's really labor intensive to rub out a finish starting with 600 grit. 600 grit sounds like fine paper but it really scratches the finish and takes a lot of elbow grease to polish the scratches out. It would just be better to get it pretty smooth while you are applying the finish and start with 1500 grit after the last coat.
Just be sure you thoroughly clean the polish off your project before you start applying poly again.
Thanks. Yeah, I got some Dupont Prep-sol (wasn't that easy to find) and removed the wax/polish and did a light sanding. There is still poly on the wood, except for those bare spots. It makes sense to take extra care applying a smooth coat of poly to avoid excessive sanding. I have sort of been doing the opposite, assuming I was going to sand after every one or every other one. I am able to put on a couple of coats per day (with about 12 hours between coats).
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>>>> Six coats of oil-based poly wiped on.
That means you had about the equivalent of two--maybe three--coats of brushed on finish. That is too little and sand-thru was very possible. When using a multi-step rub out process, you want to have at least three brushed on coats--but four is better. When using oil based poly, be sure the again allow your finish coats to cure for at least four weeks. Oil based varnishes are very slow to cure and fully harden.
I would scuff sand the existing finish with 320-400 grit paper and then re-coat. No reason not to use a brush as your rub out process will eliminate any brushing miscues.
That means you had about the equivalent of two--maybe three--coats of brushed on finish. That is too little and sand-thru was very possible. When using a multi-step rub out process, you want to have at least three brushed on coats--but four is better. When using oil based poly, be sure the again allow your finish coats to cure for at least four weeks. Oil based varnishes are very slow to cure and fully harden.
I would scuff sand the existing finish with 320-400 grit paper and then re-coat. No reason not to use a brush as your rub out process will eliminate any brushing miscues.
I have to ask a question, why did you wait four weeks for the poly to dry? Good oil base poly should dry 1-2 days at most. IMO I would wet sand with 220 -320 paper till smooth. Clean with paint thinner get a new can of oil based gloss poly cut the poly 60/40 with thinner and wipe on with a lint free ball of cotton called a "rubber" no more than three coats. Let dry two days. Rub with the grain with 4 ought steelwool to the gloss you want. Wax with paste wax. Good luck :yes:
Big difference between drying and curing
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>>>> why did you wait four weeks for the poly to dry? Good oil base poly should dry 1-2 days at most.
Oil based finish dry/cure in two steps. First the solvent evaporates and the surface feels dry. This occurs in 12 - 24 hours for most oil based finishes. After the solvent has evaporated, the remaining varnish begins to cure by being exposed to the oxygen in the air. This this process is called oxidation. The oxidation process is slow and a finish can take 2-4 weeks to fully cure to the point of full hardness and protection.
For best rubbing out results with oil based finishes, you want the surface to be a hard as possible.
Oil based finish dry/cure in two steps. First the solvent evaporates and the surface feels dry. This occurs in 12 - 24 hours for most oil based finishes. After the solvent has evaporated, the remaining varnish begins to cure by being exposed to the oxygen in the air. This this process is called oxidation. The oxidation process is slow and a finish can take 2-4 weeks to fully cure to the point of full hardness and protection.
For best rubbing out results with oil based finishes, you want the surface to be a hard as possible.
You are right curing is different than DRYING but, you can rub lightly with 4 ought wool to just cut the gloss even if finish is not cured (fully harden). I may have not made myself clear. Sorry.
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