Hello! I just finished applying some oil based poly after letting a few coats of Tung oil dry over the stain. I ended up doing 6 coats on the body and 5 on the neck, and both are now very shiny and smooth, and I can see a clear reflection. I was wondering what anyone could recommend as a good method to hand polish everything to get out the little scratches left behind, because I’ve read about using waxes and car polishes, but I’m not too sure what’s best. Anything helps!
I used it on my buiild with a tru-oil finish. Good after a 2000 grit sand to bring shine back. Also used on my fender and PRS guitar finishes to remove scratches.
First you wait a couple of weeks for it to cure and harden properly. Thus is very important and it can’t be hurried. Trying to polish straight away and the surface is too soft to take a good shine. (though I often do the first sand -see below- after a couple of days as it greatly increases the finish surface area and allows the remaining solvents to evaporate more quickly).
You then have to sand the surface flat. It may look shiny now, but the surface won’t be properly flat and there will be small dips and bumps in it. So you’d typically start wet sanding with P600 wet and dry on a sanding pad, and sand until there are no small bright areas left at the bottom of dips. Holding the guitar up to the light at a shallow angle helps to see these. Once the surface is flat, then carry on wet sanding with progressive grits, so P800, P1200, P1500 and P2000. I also do P2500 but some stop before then. Each sanding should remove the coarser marks left by the previous grit. Clean off the sanding residue first before changing grits.
Use water with a drop of detergent in it to prevent the paper clogging and it helps to soak the paper for a while first, especially when sanding curves as it makes it more flexible. Avoid using really cheap wet and dry paper from Amazon, eBay and the like. I’ve tried it but it’s far too rigid and the paper cracks, and the grits are coarser than stated and just fall off the paper when used, causing scratches on the finish.
You don’t want to get water into any holes in the body, as the wood can swell and crack the finish, so block small holes up with wax and paint varnish on the inside of big holes to seal the wood.
For this reason, some people prefer to just dry sand. You tend to use more paper this way as it clogs up and I find each grade of grit leaves a rougher finish than wet sanding. You can always do wet sanding on areas away from holes and dry on those areas. 3M ScotchBrite do a range of scouring pads that approximate steel wool grades, and they can be used as well. I think it helps if the finish is sanded flat first as I find them a bit too soft to level the surface and remove small dips (even though it looks like you have). I have packs of the maroon, grey and white pads, which are like 00, 000 and 0000 steel wool.
Now it is time to use polishing/rubbing compounds. Normally a coarser one to start with, and then a finer one (you can normally get coarse, medium and fine and can use all three). Plenty of car care products that fit the bill. Meguaires ScratchX2.0 is a good fine polish.
Apply with microfibre or lint-free cloths and polish off with clean cloths as normal. You should now have a super-shiny finish.
I don’t use any polish, but some do (though if you’ve put enough effort in it won’t add anything). If you do polish, avoid any with silicone in, as it makes it near-impossible to repair any finish if you get big chips or scratches. Carnauba wax polish is safe to use and a standard car care product.
Oh, and don't sand any hard corners. Gently sand over them with paper on a solid block, with the block firmly on the body. Don't sand the edge directly. It's so easy to sand through on and rounded section, and even more so on a sharp corner. Polishing with a polishing compound will smooth off the very edges.
How to polish oil poly finish?
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