how fine is too fine...sanding before buffing.

fatdaddypreacher

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title pretty much sums up my question. How fine of a grit is adequate before moving to buffing wheel.....using lacquer? I have gone as fine as 2000, but may be overkill. thanks.
 

cmjohnson

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I sand to 2500 before buffing, because I have up to 2500 grit cloth backed sanding discs. (They make them up to 4000 grit in the ASC brand, but I haven't bought finer than 3000. That stuff loads up if you look at it wrong.)

Go as fine as you want. Every finer grit you use just makes the buffing stage that much easier.
 

ARandall

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I have now switched to using the 3M papers....the coloured ones for the different grits.

I probably get to the 1200 or 4000 equivalent grade before I move to a cutting compound, then to meguiers compound. I'm all drill based rather than a buffing wheel, so I need more prep to get rid of scratches as the buffing process is less effective.
 

fatdaddypreacher

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well, i've only done mine by hand, but would't mind going orbital....is it safe to use an electric orbital hand sander? and if so, would that be wet sand, or dry? thanks guys
 

cmjohnson

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With modern high tech sanding products like the USC velcro backed cloth sanding discs, I prefer to sand dry and use compressed air to blow off frequently. I no longer like to wet sand because if any water intrudes and gets into the wood, the wood swells up and will stay that way until the added moisture eventually evaporates out. Plus when you wet sand, you can't really see your progress in eliminating the shiny unsanded spots until you stop what you're doing and dry it off. When you dry sand you just wipe the dust away and can even see the progress while sanding.

I'm getting better results ever since I switched to dry sanding with USC media.

If you're sanding to 2500 grit, you don't need to use cutting compound. Use a variable speed rotary polisher, Meguiar's 205 finishing compound, and a final finishing foam pad at a moderate speed. Keep the pad damp, not sloppy wet, and keep it moving. When in doubt, slow down the RPMs.

I have a low opinion of orbital buffers. My experiences with one were such that I quickly gave it to my brother. I use a variable speed 6 inch rotary polisher and I also have a 3 inch polishing head for it as well. I plan to soon buy a detail polisher, a junior sized rotary buffer, and equip it with one inch and two inch velcro arbors. It can be used for both sanding and for buffing/polishing. Velcro sanding discs are available in any grit in all these sizes in addition to microfiber polishing pads.
 
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fatdaddypreacher

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thanks, cm. sounds great. i have a bench mounted wheel buffer that has given excellant results. just wanted to see if i could shorten the sanding process without sacrificing quality. my old elbows are getting tired of all the hand sanding and i can't stand up as long as i used to. i appreciate the info.
 

cmjohnson

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Use velcro backed papers and a random orbital sander (variable speed is best) for all your flat area sanding. Leave the curves and corners for hand sanding. It'll cut your sanding time down to just minutes per grit.

I'm paranoid about sanding thru but I've never ever had a sand-thru on a flat surface using a random orbital sander unless I intended to. (Finish removal. Much coarser grits.)

Your local automotive paint and body supply store will have an assortment of sanding supplies you'll want to use once you check them out and try them. I use Mirka and USC papers.
 

LtDave32

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well, i've only done mine by hand, but would't mind going orbital....is it safe to use an electric orbital hand sander? and if so, would that be wet sand, or dry? thanks guys
FDP, i've had great success with an orbital car buffer. Take it to 2000 grit, then go to a cutting compound, then change bonnets, then a medium compound, change bonnets again and go with the fine, scratch removing compound.

Once you hit 1500 paper, it's largely a matter of a decent buffer and proper compound.

When going through the grit papers, keep everything super clean. change your water, add a drop of detergent. Don't crease the papers, as that makes a sharp edge on the folded paper. Don't bear down on it, let the paper do the work. Sand in one basic direction for one paper, change direction for the next finer grit paper. You are only trying to remove scratches from the previous grit at this point.
 

Stephmon

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I find these shorten the sanding process immensely. The key is that the particles are incredibly uniform, so there are no 'extra deep' scratches introduced at any stage. That means the next finer grit is smoothing a very uniform 'base' and you don't have to go down further, to clean up a deeper swirl, left by grit particles that are not uniform. I go 1500-3,000, then polishing compounds with an orbital buffer and finish with swirl remover by hand with a sponge.
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LtDave32

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Use velcro backed papers and a random orbital sander (variable speed is best) for all your flat area sanding. Leave the curves and corners for hand sanding. It'll cut your sanding time down to just minutes per grit.

I'm paranoid about sanding thru but I've never ever had a sand-thru on a flat surface using a random orbital sander unless I intended to. (Finish removal. Much coarser grits.)

Your local automotive paint and body supply store will have an assortment of sanding supplies you'll want to use once you check them out and try them. I use Mirka and USC papers.

Auto parts stores are a great source of finishing supplies, yes.
 

Freddy G

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I go to 1200 and then the buffing wheel. It's a matter of efficiency. If my buffing wheel can take out the 1200 grit sanding marks, why waste time spinning my wheels with 2000 or 4000 grit paper. It's actually the lower grit paper that is more important......the sandpaper's job is to flatten the finish and for that anything over 1200 is useless....you are more polishing than flattening.
 

cmjohnson

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That also depends greatly on what grade compound you use. Coarser compound will take out coarser scratches but won't leave as good a polish, either. You may have to go to a finer compound to finish the job. And that requires a second dedicated wheel. You can't rake all the previous compound out of your buffing wheel, go to a finer compound in the same wheel, and expect perfect results. You just can't clean the wheel that thoroughly.

I take my final finishing method straight out of the automotive detailer's playbook. When going for a true show car grade finish, absolutely flat and level, with perfect reflections with no haze in them, in order to get the true dipped in glass look, you basically go as far as you can with highest quality sandpapers and then buff your way to perfection with the final finish grade of polishing compound.

Everything matters. Your sandpaper grits, the quality of the paper, your choice of buffing pad, and the compound you use.

I spent a few years working at a shop that had the big Stewart-MacDonald 14" buffing wheel system. It was pretty good. But I also had it throw a guitar on the floor while I was buffing it. Actually destroyed the guitar. Not a great memory.

I much prefer to use a rotary polisher as would be used in auto detailing. I secure the guitar in place so it won't be pushed off the bench, and use the polisher with absolutely no more pressure than is needed.

My finishes have previously been my weak point in guitar making. I've been very focused on turning it into one of my strengths instead. It has taught me to be MORE patient. The results are worth the extra effort.
 

Freddy G

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That also depends greatly on what grade compound you use. Coarser compound will take out coarser scratches but won't leave as good a polish, either. You may have to go to a finer compound to finish the job. And that requires a second dedicated wheel. You can't rake all the previous compound out of your buffing wheel, go to a finer compound in the same wheel, and expect perfect results. You just can't clean the wheel that thoroughly.
Well yeah. I start with a medium compound on the wheel, and then move to a fine compound on another wheel.

I take my final finishing method straight out of the automotive detailer's playbook.
And I take mine out of Freddy's guitar finishing book....which would make any show car finish green with envy. :cool2:

But I also had it throw a guitar on the floor while I was buffing it. Actually destroyed the guitar. Not a great memory.
That wasn't the buffer's fault. That was the operator's fault.

My finishes have previously been my weak point in guitar making.
Not mine. I don't mean to be full of braggadocio, but since you are for some reason questioning or trying to correct my statements while at the same time admitting your finishing skills aren't strong....what do you expect?

The results are worth the extra effort.
That we can agree on!
 

cmjohnson

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Yeah, it was the operator's fault when, with the assistance of the torque of the buffer, a newly made 16 inch archtop I'd just finished building went CRUNCH on the floor. It'd have survived except that it broke at a spot on the carved top that had been carved too thin, and was thus too weak. So actually it was "percussive quality control" and kept me from shipping out a guitar that would probably have failed some time down the road.

I'm not correcting you or anything like that, just sharing my perspective. Enjoying the exchange of ideas, techniques, and, results.
 

fatdaddypreacher

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I go to 1200 and then the buffing wheel. It's a matter of efficiency. If my buffing wheel can take out the 1200 grit sanding marks, why waste time spinning my wheels with 2000 or 4000 grit paper. It's actually the lower grit paper that is more important......the sandpaper's job is to flatten the finish and for that anything over 1200 is useless....you are more polishing than flattening.
that's exactly where i was headed. all i want to do is expedite the buffing process. I've always known for decades that the finishing process was a prolonged exercises in scratch removal. I just wasn't certain how 'deep' of a scratch could be removed with the buffing process. I don't need the practice to spend endless hours sanding with fine paper that won't make a difference in the finished product. Thanks for the response and your invaluable contributions to this forum.
 

fatdaddypreacher

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That also depends greatly on what grade compound you use. Coarser compound will take out coarser scratches but won't leave as good a polish, either. You may have to go to a finer compound to finish the job. And that requires a second dedicated wheel. You can't rake all the previous compound out of your buffing wheel, go to a finer compound in the same wheel, and expect perfect results. You just can't clean the wheel that thoroughly.

I take my final finishing method straight out of the automotive detailer's playbook. When going for a true show car grade finish, absolutely flat and level, with perfect reflections with no haze in them, in order to get the true dipped in glass look, you basically go as far as you can with highest quality sandpapers and then buff your way to perfection with the final finish grade of polishing compound.

Everything matters. Your sandpaper grits, the quality of the paper, your choice of buffing pad, and the compound you use.

I spent a few years working at a shop that had the big Stewart-MacDonald 14" buffing wheel system. It was pretty good. But I also had it throw a guitar on the floor while I was buffing it. Actually destroyed the guitar. Not a great memory.

I much prefer to use a rotary polisher as would be used in auto detailing. I secure the guitar in place so it won't be pushed off the bench, and use the polisher with absolutely no more pressure than is needed.

My finishes have previously been my weak point in guitar making. I've been very focused on turning it into one of my strengths instead. It has taught me to be MORE patient. The results are worth the extra effort.
i use two different compounds and have dedicated wheels for each. I too fear getting a guitar yanked out of my hands, or just bumped into the table. what a horror story. to be honest, i've never thought too much about paper quality, but it makes a world of sense. i'm going to have to spend more attention to that in the future. thanks for the input
 

LtDave32

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that's exactly where i was headed. all i want to do is expedite the buffing process. I've always known for decades that the finishing process was a prolonged exercises in scratch removal. I just wasn't certain how 'deep' of a scratch could be removed with the buffing process. I don't need the practice to spend endless hours sanding with fine paper that won't make a difference in the finished product. Thanks for the response and your invaluable contributions to this forum.
One of the most annoying things one can encounter in the buffing stage is one or more deep scratches in an otherwise "buffable" finish. This is usually the result of some odd foreign matter getting trapped under the paper when wet-sanding, or it could be a chipped sharp edge of the paper that was a result of sharply creasing the paper. These wet papers are designed to be soaked in water for long periods of time. Better results can be had by soaking them overnight in water before you even start the job of wet-sanding. Less prone to "edge chip" that way.

And again, let the paper do the work. Deep scratches also happen as a result of bearing down on the sanding block.

Clean the paper of lacquer build-up often. Keep it wet. Check for debris.

Once you have the whole project down to the grits we mentioned, 1200, 1500, whatever, it should buff up beautifully with two or thee progressively finer compounds.
 


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