Getting rid of wet sanding scratches with polishing.

I have built several instruments, this is my second time doing a nitro finish.

For the life of me, I cannot seem to get rid of the scratches left behind from my wet sanding. I sanded 800, 1000, 1200, 1500, 2000.

Some people would say it looks great I'm sure, I say it looks terrible. Looked better with the orange peel before sanding at all.

I am using an inexpensive turtle wax random orbit buffer/polisher. I have also attempted to do it by hand.

The guitar gets to a very nice buffed mirror shine but it is FULL of the scratches and streaks that are clearly left behind from my wetsanding.

For buffing compounds I am using Stew Mac Colortone Medium, Fine, Swirl Remover and then Mequir's Scratch X 2.0

I am using a different pad for all compounds.

What on earth am I doing wrong? Am I not spending long enough on each grit sandpaper? How long on each grit to you spend?

If using an orbital type buffer/polisher with a foam or cloth pad, how long do you buff for? Do you apply the compound and buff for several minutes? Under a minute? Until it becomes dry? Do you continue after it's dry?

I wet sanded in one direction, with the grain, with a rubber sanding block. Speaking just of the guitar back, I sanded for a couple of minutes with each grit.

Still there are long sanding scratches spanning the entire length of the back of the guitar. I feel pretty certain they are not going to buff out with what I'm using.

Does anybody ACTUALLY get a finish that is crystal clear and like a mirror? Are these scratches something I just need to accept? Do I need a full buffing arbor with menerza compound to get rid of them? Do I need to sand to 40,000 grit to remove them? My finish is certainly like a mirror.. just a scratched up one.

Close up of scratches. I have gone back with medium and fine colortone compounds. Still have Swirl remover and Scratch X to do. Though they seem to just bring out more mirror shine, these scratches remain. The finish color is a cream white.

http://i880.photobucket.com/albums/ac7/IrvingGreene/IMG_1467.jpg

Hi. Have no fear, you can get those scratches out!

I've suffered the same problems as you're having.

I think the main problem is that you're sanding in one direction.
Since your finish doesn't have "grain", you don't need to sand
in one direction like you would on bare wood.

Usually it's recommended to sand in a circular motion, but
some people like to sand straight in one direction for one
grit, and straight in the perpendicular direction for the next
grit, etc.

Even if you fix your sanding technique you may have some
significant scratches when you get to 2000. At least I do,
maybe because I don't spend enough time on each grit.

I have that same cheap Turtle Wax buffer and have not
gotten good results from it. To get a nice, scratch-free
finish I end up doing hand buffing with 3M rubbing compound,
followed by 3M finesse-it II. Pics of the bottles here:

https://lh6.googleusercontent.com/-5W4Wsuw4rBw/TTuhUEHWU0I/AAAAAAAABQo/aDSyIoK2h-Q/s800/IMG_6629.JPG

But the key thing is the 3M rubbing compound. You can get
scratches out by hand pretty easily with it. This guitar got
its scratches sorted out with 3M rubbing compound.

https://lh5.googleusercontent.com/-nNPqL3RU5Zk/TTuhUU-s7mI/AAAAAAAABQo/0-adppJabJQ/s800/IMG_6631.JPG

If using an orbital type buffer/polisher with a foam or cloth pad, how long do you buff for? Do you apply the compound and buff for several minutes? Under a minute? Until it becomes dry? Do you continue after it's dry?

I wet sanded in one direction, with the grain, with a rubber sanding block. Speaking just of the guitar back, I sanded for a couple of minutes with each grit.

Still there are long sanding scratches spanning the entire length of the back of the guitar. I feel pretty certain they are not going to buff out with what I'm using.

Does anybody ACTUALLY get a finish that is crystal clear and like a mirror? Are these scratches something I just need to accept? Do I need a full buffing arbor with menerza compound to get rid of them? Do I need to sand to 40,000 grit to remove them? My finish is certainly like a mirror.. just a scratched up one.

Thanks brother! I'll give it a try!

Thanks brother! I'll give it a try!

Great -- no reason to move on to swirl remover until those
scratches are out. I know exactly what you mean about a
mirror finish except for the scratches!

Nice fiddle, Flat5!

Just tried the 3m rubbing compound and it helped some, but the majority of my scratches are still there... I applied it by hand. Vigorously. I'll try it with this crappy turtlewax buffer.

When applying by hand, how long of a duration do you work it in? Do you work it well beyond when it starts to seem dry?

One conclusion I'm coming to is that these Stew Mac colortone compounds suck. Anyone like them or have good results? This 3m stuff and meguires beats the pants off it.

If the compound has dried and you continue buffing, wouldn't that create scratches moving dried stuff around?

The scratches I am battling are certainly from wet sanding. I wet sanded all in one straight direction. 800 to 2000 grit. I am applying the compounds in a swirling circular motion and have no problem with scratches like that, just the long straight scratches.

Holy hell. I just went back to 2000 grit and cross hatched across my current problem scratches and now I simply have new perpendicular scratches that my compounds are not removing. They are 2000 grit scratches. Why are these not coming out for me?! I am using 3M rubbing compound.

Very odd. I was going to say that you were using too fine a grit to take out the scratches, but that's clearly not the case based on your last post. It defies analysis.

One suggestion: are you pressing down while sanding? Don't. Let the sandpaper do the work.

What lacquer are you using, how did you apply it, and how long did you let it hang?

I've seen this before! Sand in one direction with each grit, and perpendicular for the next grit. Wipe off the excess water frequently and check to make sure all the scratches are gone from the previous grit, before moving on to the next. You may also want to use a better quality paper, like finesse brand. Cheaper sandpaper sux! One tiny oversized grain can ruin a good finish!!!!

I use a corian sanding block instead of rubber for all the flat surfaces and the finish is like glass.

Here is an example,

This sounds like you are sanding before the lacquer has dried. As above, how long did you let your finish dry before sanding?

What lacquer are you using, how did you apply it, and how long did you let it hang?

It is Mohawk Instrument Lacquer. Hung for about 2 weeks. HVLP sprayed. Followed what I think is a fairly standard spraying procedure: Pore filler. Two 50/50 wash coats. 3 Full clear coats. Flat sand. Color. 5 coats. Flat sand. 5 more full coats. Flat sand. 3 final coats. 2 Week cure. Waited 1 hour or more between coats.

These scratches are starting to come out.. I'm switching between a few different compounds testing stuff out. It's taking some serious elbow grease and time, but I think eventually I'll get them out..

I've got some turtle was was rubbing and polishing compounds here I'm tempted to try, just because I have them. Bad idea?

It is Mohawk Instrument Lacquer. Hung for about 2 weeks. HVLP sprayed. Followed what I think is a fairly standard spraying procedure: Pore filler. Two 50/50 wash coats. 3 Full clear coats. Flat sand. Color. 5 coats. Flat sand. 5 more full coats. Flat sand. 3 final coats. 2 Week cure. Waited 1 hour or more between coats.

These scratches are starting to come out.. I'm switching between a few different compounds testing stuff out. It's taking some serious elbow grease and time, but I think eventually I'll get them out..

I've got some turtle was was rubbing and polishing compounds here I'm tempted to try, just because I have them. Bad idea?

Two weeks in Maine's climate is probably not long enough. I would be willing to bet if you continue polishing it now, those scratches will reappear at the end of summer.

Two weeks in Maine's climate is probably not long enough. I would be willing to bet if you continue polishing it now, those scratches will reappear at the end of summer.

I know I'm supposed to let it cure for like 18 years, I just don't have the patience for that. haha Why and how would scratches that have been removed reappear over time?

Seventeen coats, more or less, and two weeks cure time? There's yer problem. Let it hang another four weeks and try again. The more you polish, the more finish you remove, eventually you're going to burn through the finish, and really be po'ed at yourself.

As Colt says, even if you get it smooth and glossy now, it will probably show grain and sanding scratches once it's done curing. Not to mention that if the finish is still soft it will imprint from your case or stand. A little more patience right now will pay off big in the long run.

I completely understand grain lines showing as the finish continues to cure. I'm ok with that. The last, and only, other guitar I did this process to was at Roberto Venn a few years back and we hung them for 2 weeks and everything turned out fine - except for grain lines showing up over time. No big deal.

So now why would inadequate cure time cause me to have trouble buffing out 2000 grit scratches? That just doesn't make sense to me. Even mohawk says to wait a minimum of 4 DAYS before final sanding and buffing. I hear your warning and accept that essentially you are right in that it would be better for a number of reasons, but I don't think it's why I'm having trouble buffing these scratches out.

It seems like my technique must be wrong. Or I'm using an inadequate compound. Or I'm sanding too aggressively. Or not sanding enough with certain grits or something.

I'm not too worried about burning through my color right now if I can't even buff down to the bottom of these 2000 grit scratches.

Even mohawk says to wait a minimum of 4 DAYS before final sanding and buffing.

...but, isn't that based on three coats or something like that? You've got considerably more than that, which means a lot more material to shrink and reveal flaws.

but I don't think it's why I'm having trouble buffing these scratches out.

...because at this point you're not buffing scratches out, you're just moving the top layers around.

It seems like my technique must be wrong. Or I'm using an inadequate compound. Or I'm sanding too aggressively. Or not sanding enough with certain grits or something.

Or your finish hasn't cured.

Seriously, the golden rule applies here as much as anywhere, it's your guitar, do what you want with it. I'm not here to argue, not in the least, but you did ask for help. It seems that you've buffed the daylights out of the poor thing, and the problem persists. If buffing hasn't solved the problem, more buffing is probably not the answer.

The best of luck to you. I know you'll whip it in the end, and have another project to be proud of.

Long sigh. You're probably right. Clearly I don't know. lol I'm a bit frustrated on my end. I really appreciate the tips and advice, I do. Cheers.

I have certainly heard of waiting from 2 to 6 weeks before final sanding and buffing. I find it odd though that even Stew Mac's directions of lacquer finishing says to wait 4 days before final sanding: http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/Seagrave_Nitrocellulose_Spraying_Lacquers/Seagrave_Nitrocellulose_Spraying_Lacquer.html?actn =100101&xst=3&xsr=1380&tab=Instructions

I have been told by others that they have done their final finish work after even only letting the guitar cure for 3 days and the only repercussion is grain lines showing later down the road.

I love the ideas and tips here, I'm just not convinced that my problem is too short cure time. I may just be buffing like a puss.

Just one simple question. About how long does it take you, either by hand or with a simple orbital buffer, to buff the backside of a guitar with one compound? Is it a matter of seconds, minutes, five minutes?

You probably can final sand and buff after 4 days, but 4 days in an 80 degree, 30% humidity room isn't the same as 4 days in 50 degree 85% humidity weather.

Personally, I don't see why waiting for the lacquer to get
harder is going to make it easier to remove scratches.

Irving, when I use the 3M rubbing compound I apply it with
quite a bit of pressure, but not until it gets dry.

Take a day or so off to unwind and think about things.

I know what I'm doing next time. Tru oil! haha

I think it's very possible I'm just not buffing with enough manpower.

Well, I'm buffing the F out of it now, really bearing into this little low powered turtle wax buffer. Almost even working up a sweat! Almost. And my scratches are hugely improving. Still got a ways to go though. I do not feel anywhere close to burning through and the lacquer is not getting hot. Very mildly luke warm, but not hot. Should you have to work hard at it like this?

Don't think so. Take a break and check out this video from the LMI Video site:

http://www.youtube.com/watch?v=92YWLyqwjYI&feature=player_embedded

I've never been steered wrong by following advise off these videos. Check out especially what he says about the finer grades of sandpaper gradings.

It's a workout, but not like chopping wood, which is what it sounds like you're having to do.

Can't imagine that scratches weren't all but gone at 2000 grit. In the video, he stops sanding/leveling at 1000 grit and the guitar looks glassy. THEN he starts buffing.

He does caution about waiting to begin leveling/finish sanding until ample cure time has elapsed, though.

Good Luck.

That's what it needed. Just some serious elbow grease. Bear in mind that I'm using a very low powered, probably cheapest on the market $20 buffer/polisher. It's hardly better than doing it by hand I've decided. I just spent probably 10 minutes buffing the backside until my arm felt like it was going numb and it's looking great. I'll post a picture later.

Thank you. Going to check it out.

Don't think so. Take a break and check out this video from the LMI Video site:

http://www.youtube.com/watch?v=92YWLyqwjYI&feature=player_embedded

I've never been steered wrong by following advise off these videos. Check out especially what he says about the finer grades of sandpaper gradings.

It's a workout, but not like chopping wood, which is what it sounds like you're having to do.

Can't imagine that scratches weren't all but gone at 2000 grit. In the video, he stops sanding/leveling at 1000 grit and the guitar looks glassy. THEN he starts buffing.

He does caution about waiting to begin leveling/finish sanding until ample cure time has elapsed, though.

Good Luck.

Irving,

It sounds like you are solving the sctarches on your own, so take this only as a suggestion for attacking the root cause of the scratches next time.

If I was to bet I would guess:
1) a major problem is always going in the same direction. Sanding in straight lines is a great technique, but as said before, change direction 90 degrees with each new grit and then do not progress to the next grit until all the sanding lines running in the direction of the previous grit have been eliminated. What you're seeing may not be 2000 grit scratches at all, but 400 or 600 (or whatever you began with) that were never removed before moving to the finer grits.
2) you were not soaking and cleaning your wet sanding papers enough. Even when using the above technique, sanded off finish can kind of "ball up" into a little pellet betrween your paper and the guitar and scratch the heck out of it. You can feel when this is happening if you keep light pressure and let the paper do the work. Clean and swap out your papers constantly during the wet sanding to avoid this.

If you do this with a well cured finish you will be able to get a great final without all the buffing work you're experiencing now.

Good luck,
Rex

To get rid of grit marks, you really need to look at "automotive detailing" products, especially professional ones rather than the high street products.

Some of the ultra fine finishing polishes give an almost optical finish.
Example Britemax #4 Black Max ultra fine polishing glaze (considerably finer than SwirlX)
http://www.britemax.co.uk/acatalog/Black_Max.html
http://www.britemax.co.uk/acatalog/index.html

Why car stuff? - people spend an absolute fortune on getting car paintwork right, much larger industry than guitar making. The paints and finishes on a modern guitar is car paint..

Well, I'm buffing the F out of it now, really bearing into this little low powered turtle wax buffer. Almost even working up a sweat! Almost. And my scratches are hugely improving. Still got a ways to go though. I do not feel anywhere close to burning through and the lacquer is not getting hot. Very mildly luke warm, but not hot. Should you have to work hard at it like this?

I think a problem is that the pressure you're applying to the
buffer is getting distributed over a large area. When I removed
scratches with the 3M rubbing compound I was applying with just
a finger or two and rubbing reasonably hard. In doing so the
scratches went away quickly.

By the way, I consider the 3M rubbing compound to be a
completely professional product.

Whilst I do prefer the rotary sander/polisher (£50) for the extra grunt, the dual-action (£80) polisher is less likely to do damage. These are not high street diy tools. That's to say not a "TurtleWax Polisher" (Halfords do a similar 12V car outlet version rofl) or an orbital finishing sander, for sandpaper.

http://www.i4detailing.co.uk/
Silverline rotary & Kestral DAS-6 dual-action
http://www.i4detailing.co.uk/acatalog/129659.jpghttp://www.i4detailing.co.uk/acatalog/das61.jpg
They need different backing discs but take the same foam polishing pads.

The foam pads prevent excessive pressure and come in many sizes. The big drum types can be used edge-on for sides.

You guys rock. Thank you all.

And in regards to what TRex said, I think that bits of lacquer gumming up on the paper were a big part of my scratch problem.

I am using 3M rubbing compound followed by Stew Mac's Medium, Fine and Swirl Remover THEN followed by Meguires Scratch X. This is probably serious overkill.. Maybe I will cut out a few. I've only done the 3M so far. Which would you cut out? Is there a real fine polish or glaze I should apply after the ScratchX?

I am using 3M rubbing compound followed by Stew Mac's Medium, Fine and Swirl Remover THEN followed by Meguires Scratch X. This is probably serious overkill.. Maybe I will cut out a few. I've only done the 3M so far. Which would you cut out? Is there a real fine polish or glaze I should apply after the ScratchX?

I suggest you just experiment a little. In my challenge build
this year I used the 3M Rubbing compound followed directly
by 3M Imperial Hand Glaze. That was it.

http://www.amazon.com/3M-Imperial-Hand-Glaze-Finish/dp/B0002NUNIO/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1338927206&sr=1-1-catcorr

By the way, here's a comparison chart that's handy, even
if it doesn't show lots of products:

http://www.auto-geek.net/charts/wax-cut-chart-master.htm

https://lh5.googleusercontent.com/-nNPqL3RU5Zk/TTuhUU-s7mI/AAAAAAAABQo/0-adppJabJQ/s800/IMG_6631.JPG

awesome. I'm just starting to polish my challenge build. It's like a mirror but still see scratches. I haven't spent much time on it so it will get better. Exciting to watch the shine come up.

Quick question. Is hand rubbing a long process. I'm not sure whether to expect its 1/2 hr or 5 hrs.

I do have a orbital polisher for cars. Never used so thinking of using that on the guitar.

Cheers

I suggest you just experiment a little. In my challenge build
this year I used the 3M Rubbing compound followed directly
by 3M Imperial Hand Glaze. That was it.

http://www.amazon.com/3M-Imperial-Hand-Glaze-Finish/dp/B0002NUNIO/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1338927206&sr=1-1-catcorr

By the way, here's a comparison chart that's handy, even
if it doesn't show lots of products:

http://www.auto-geek.net/charts/wax-cut-chart-master.htm

Nice, that chart looks very handy.

awesome. I'm just starting to polish my challenge build. It's like a mirror but still see scratches. I haven't spent much time on it so it will get better. Exciting to watch the shine come up.

Quick question. Is hand rubbing a long process. I'm not sure whether to expect its 1/2 hr or 5 hrs.

I do have a orbital polisher for cars. Never used so thinking of using that on the guitar.
Cheers

I'd say it take me around 30 minutes each to do the
front, back, and sides with the 3M rubbing compound.

Then I use the hand glaze, and spend about
10 minutes each on each of the 3 surfaces.

I'm not an expert, but have gotten decent results through
patience. I think I've finished only about 5 guitars with lacquer
total.

My usual process after sanding to 2000 is: try my lousy
Turtle Wax buffer with the 3M rubbing compound. Then notice
that there are plenty of remaining scratches. Then use
the buffer for longer, and with more pressure, and see
that scratches still remain. Then apply the 3M compound
by hand. :oops:

I'd say it take me around 30 minutes each to do the
front, back, and sides with the 3M rubbing compound.

Then I use the hand glaze, and spend about
10 minutes each on each of the 3 surfaces.

I'm not an expert, but have gotten decent results through
patience. I think I've finished only about 5 guitars with lacquer
total.

My usual process after sanding to 2000 is: try my lousy
Turtle Wax buffer with the 3M rubbing compound. Then notice
that there are plenty of remaining scratches. Then use
the buffer for longer, and with more pressure, and see
that scratches still remain. Then apply the 3M compound
by hand. :oops:


Ok so I spent way more time. Was happy with the results. Hit a problem though. Left it on the non slip router mat. It appears that plastic/rubber is not good for a nitro finish. More buffing shoul fix it though.

Cheers

Be careful, as those mats can actually react with the finish (eat them) if left on for too long. I don't put a finished surface on those at all any more after having one lacquer finish completely ruined by one.

Irving - FWIW I have had the same problem on every build I have done. I used Deft rattle cans. I have hung bodies indoors (I live in Arizona so I don't need to worry about humidity) for 6 to 8 weeks to let the lacquer "cure." It never seems to cure and I usually sand up to 2000 - taking care to clean off the sand-paper so I'm not rubbing pieces of lacquer stuck to the sandpaper into the finish as I sand. I cannot get rid of the minute scratches. I have a Stew-Mac buffer and have tried that. Tried wet sanding up to 1000 (400 - 600 - 800 - 1000 - even used 1200) then using medium and fine Menzerna on the Stew-Mac buffer - still have the scratches. I have finally given up. I'm not sure if it is because I am using Deft rattle cans or what.

I have seen some members discuss Minwax lacquer. Went to my local Home Depot and Lowe's and couldn't find it. Then drove by a Walmart (I despise Walmart - my own issues) and something said give Mr. Walton a try...went in and there it was - cans of Minwax lacquer (the black cans). I am going to try some of that on my next build.

Just curious--anyone ever try sanding higher than 2000?

Irving - FWIW I have had the same problem on every build I have done. I used Deft rattle cans. I have hung bodies indoors (I live in Arizona so I don't need to worry about humidity) for 6 to 8 weeks to let the lacquer "cure." It never seems to cure and I usually sand up to 2000 - taking care to clean off the sand-paper so I'm not rubbing pieces of lacquer stuck to the sandpaper into the finish as I sand. I cannot get rid of the minute scratches. I have a Stew-Mac buffer and have tried that. Tried wet sanding up to 1000 (400 - 600 - 800 - 1000 - even used 1200) then using medium and fine Menzerna on the Stew-Mac buffer - still have the scratches. I have finally given up. I'm not sure if it is because I am using Deft rattle cans or what.

I have seen some members discuss Minwax lacquer. Went to my local Home Depot and Lowe's and couldn't find it. Then drove by a Walmart (I despise Walmart - my own issues) and something said give Mr. Walton a try...went in and there it was - cans of Minwax lacquer (the black cans). I am going to try some of that on my next build.

I've not used Deft lacquer to finish a guitar, but have used Minwax Gloss spray lacquer, and have been very pleased with the results.