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Hi.

i've got 2 qns.

1. When wet sanding, do u lightly sand it, or put quite some presure while sanding? The key shld be just sanding flat, and getting rid of shiny spots correct? I dont think we shld want any deep "cuts", am i rite?

2. How long shld we allow the guitar to dry from our last coat before starting on the polishing process? I hang my guitar for a week after my final coat, and when i lay in on my bed, u can actually see the design of the fabric printed onto the clear coat, like woven pressed onto it. How much longer should i wait to be safe? i mite have put on a heavier coat.

any way to make it dry faster? hair dryer?

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Thanks Jimm...that sounds like a good sensible schedule for rattle-can poly. I've been trying to do the whole clear coat in one shot, but your plan sounds better.

Weiht, you should use Drak's "sniff test"...hold it up to your face (or put it in a closet) and inhale. If you can smell the finish, it's not dry yet. Roughly...4-8 weeks for nitro, 2-4 weeks for polyurethane (I leave my poly bodies at least a month).

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hi.

just started on my perfect it 2 fine cut after sanding with 1500 grit. i found some pin holes on the finish. it is quite unsightly, could anyone tell me how to remove it?

also, if i have some sand thro, wat it the best way to cover up? i tried to spray the spot with the color again, however, the color that appears is lighter, and looks uneven as a whole guitar.

im asking because some idiot drop it, and there is a chip which i filled up with wood fillers. now im trying put the color back in. damn it

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From www.reranch.com:

Pin holes can be caused by a number of factors. The most common are contamination of the wood by wax or silicon (Armor All used on the case or plastic parts can be a source of this type of contamination), temperature changes during the spraying /drying cycle and moisture in the wood. Wood contamination can be sanded out in most cases. Wiping with naphtha will also help in removing contamination. Temperature can also play a role in the formation of pinholes. If a guitar that has been in a cool environment then sprayed (as might be the case if you are spraying in an unheated garage) and after spraying moved into a warm environment to dry, air bubbles may form as the wood warms and push their way through the lacquer leaving pinholes. The last frequent cause (and probably most common) is moisture in the wood. Water can get into the wood through washing stripper from the wood, wet sanding primer or sealer coats or not allowing a water based filler or water based dye enough time to dry.

The solution? Sanding and wiping with naphtha should remove wood contamination and not subjecting the wood to major temperature changes during the spraying and drying process will prevent pin holes caused by bubbles (note that placing newly finished wood in the sun to dry is a guaranteed way to cause pin holes). Allowing the wood sufficient drying time after wetting will most likely eliminate moisture related pin holes. A sure way to prevent pin holes before spraying the lacquer coats is to seal the wood with a clear sand and sealer on translucent finishes and sand and sealer and/or a white pigmented shellac on opaque finishes. If you didn't seal the wood and now have pinholes you may be able to drop fill them with unthinned lacquer. The lacquer will over power the cause of the hole and allow subsequent sprayed coats to flow over the holes. After spraying about two coats the "bumps" from the filling can be sanded flat. Drop filling will work on sectional pinholes but if the holes are numerous and over a large area, starting over (this time either correcting the problem and/or sealing the wood before spraying the lacquer) may be the best solution.

Also from reranch.com(to fix ur sand thru

Sanding through is easy to do. It will most likely occur over the edges of the body. If the sand through occurs during the color or clear building stage you can simply respray the sanded through area and respray the color or clear coat. Complete overspraying is usually not needed. If you sand through into the wood you will need to refill the wood. For such a sand through sand and sealer only can be used to seal the wood. The white primer can also be used but may not be necessary. To prevent future sand throughs use a block where you can and when beginning the wet sanding use a finer grade paper (#800 to #1000) to get a feel for the process. Once you are comfortable you can move down to #600 or #400 for faster sanding

:D

Edited by AlGeeEater
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  • 2 months later...

hey I have a question. If I use [url="http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/ColorTone_Aerosol_Guitar_Lacquer.html"]this[/url] (the high gloss one) from stew mac how soon should I put on the next coat? Should it be whille the old coat is still tacky? or should I wait until it hardens and than do the next coat? Also do I need to sand in between coats?

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  • 1 month later...

I thought it would be convenient to have an easily printable version of the tutorial so I copied it into a Word document and added headings etc. I'm hosting it on my web space so if you follow this link, you can download it to your PC and print it.

[url="http://www.downinfrontht.com/images/woodworking/LGMPolish.doc"]http://www.downinfrontht.com/images/woodwo...g/LGMPolish.doc[/url]

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Thanks for the tutorial...but I have a problem...

The only polishing materials I could find around here is a kit consisting of two different types of pad (for attaching to a drill) and two different sticks (fine and ultra fine --there's another kit that starts with coarse).

The instructions show them picking up the compound with the drill.

But in the tutorial, LGM is obviously using a paste that he smears onto the guitar.

So how can I adapt the tutorial for using with a stick compound?

Thanks!

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  • 11 months later...
  • 4 months later...

[quote name='LGM Guitars' post='14203' date='Jul 13 2003, 01:23 PM']
Ok, there have been a lot of paint and polishing questions asked recently, so I thought I'd do a brief description of the polishing process, first here is a list of what I use for polishing.

Stew mac Polishing compounds #1, 2, 3, and 4 (coarse, medium, fine, extra fine)
Micro cut sandpaper 2000 grit (unless my spray job sucked then I start with 1200, 1500, and then 2000)

Stew mac foam buffing pad and electric drill (soon I will have a nice big buffing wheel in the new shop though) x4 One for each compound

Water

Ivory hand soap

Patience.

Elbow grease.


Ok, This will be assumed that you have a nice clear coated body (see [url="http://projectguitar.ibforums.com/index.php?act=ST&f=10&t=1362&hl=painting+tutorial"]The painting tutorial[/url] I did for painting and applying clear)

Difference being from that painting tutorial that I usually put on about 10 coats of clear on a guitar body before final polishing is done.

So, once the paint is good and cured, we go to step one.

Step one: Sanding
First thing you need to do, is sand out all imperfections or built up edges, if you sprayed well and the paint flowed out nice this won't take very long. It generally takes me about 1 and a half hours to sand out a body starting with 2000 grit. You'll want to do this with some water with ivory hand soap mixed in. Yes use Ivory, it is the only soap on the market that is 99% oil free. (you want oil free in case you should sand to deep or discover you need to spray another coat of clear for some reason)
Sanding always in one direction (I always sand lengthways on the body) use a semi hard block and level the entire body. If you have dust spots or really large built up edges use a hard block to knock them down, then go to a semi hard block (I really like the foam block you get with micromesh)

I start with the top of the guitar as this is usually the most difficult to sand because of all the cavities. Unless there is a dust speck or something on the very edge, don't sand the edges, the clear is always the thinnest there and it doesn't take long to cut through an edge. Then do the back, and then the sides, the worst part is in the horns, this is also where the clear always seems to stay the roughest so it takes a bit longer than the rest. When you do the perimiter, I sand with the body all the way around, never across the sides, just always along them.

Sand until the entire guitar (except the edges) is an overall dull flat sheen, if you see shiny spots, keep sanding, these will become awful looking marks once it's all shiny again.

Step 2: Coarse cutting (if you have sprayed with laquer, you can skip this step as laquer is far softer than the Poly's I spray)

Apply the cutting compound all over the top of the guitar with a rag. Mount your drill with the foam pad on it on your work bench (I used to hold the drill and secure the body, but that was stupid, this is so much easier) I run about 1500rpm. Using a good amount of pressure, cut the entire top. The compound will fly everywhere, so use old clothes, a shop coat, and safety glasses, a particle mask is a good idea too. I personally start with the lower half of the top and work through the cavities and stuff. You'll notice alot of shine come back with even the coarse. Keep wiping it clean and applying compound until you can't see the 2000 scratches anymore. BE CAREFUL AROUND EDGES!!!!!!! NEVER let the wheel come into the edge, I always polish so that the rotating wheel is going OFF the edge, there are 2 reasons for this.
1: If you are letting the wheel come into the edge, there is way more pressure and cutting through the paint is far more likely.
2: If it grabs a corner, you run the risk of the body being taken from your hands and zinged across the room (have had a couple close calls but never actually lost a body yet :D )

Oh, during all the cutting stages, you'll want to also wear rubber gloves, this crap will be messy, and the rubber gloves also helps you to hold onto the rather greasy compound.

Now do the back the same way. Then the sides, but be very careful on the sides, you don't want to burn through an edge. Inside the horns is very difficult, you can do these by hand if you want, but the foam pads will reach all the way in, even on the deep scoops of an ibanez body, but watch out for the plastic backer on the pad, it will cut into your clear in a big hurry.

Step three: Medium compound

Basically repeat step two with the Medium, just make sure to use a NEW pad and clean all the coarse compound off before you start with the medium.

The guitar will really start to shine now, keep wiping the body and checking for any deep scratches that are left over and get rid of them. At this point you will also start to notice that if you didn't sand everything flat all the marks are starting to show badly again. You might want to resand at this stage before you get to far into it. At this stage, when you wipe the body clean, use a soft cotten pad, not paper towel as it will put in scratches.

Step four: Fine compound

Same thing again with fine now. I use a little more pressure with the fine though (again use a NEW pad). Now this thing is starting to glow, with the fine compound I also hit all the edges now, but still be careful, just the foam pad alone will cut through an edge if you use to much pressure or leave it there to long.

Again, wipe it all down and look it over, it should look pretty close to factory finish now.

Step five: Extra fine (swirl remover)

This step is basically the same except I use 2000RPM and light pressure, you are now just buffing the body, not cutting, you dont' want to put heat marks or rub marks into the clear at this point. Again use a new pad and just do small area's at a time with the swirl remover, a little bit of this stuff goes a LOOOOOOONNNNNNNGGGGGG way, and it flings all over everything. Once you've gone over the entire guitar with this, wipe it all down once more and check everything, make sure it's perfect, if you have to go back, go back.

Step six: Finishing

Wipe it all down with a flannel cloth, and if you want, put some wax on it, I use meguire's automotive wax and then clean it all down with some Dunlop guitar polish once I'm done waxing (I wax by hand) then when you assemble, be sure to always set the body on flannel cloth. If you scratch it and it's your guitar, it's a piss off, if you scratch it and it's a customer guitar, it's a nightmare!


Hope this has been helpful to everyone, next time I polish out a body I will take pics of the process and add them to this thread.

If you have any questions please feel free to ask :D

Jeremy
[/quote]

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  • 9 months later...

This seems like a stupid question but I have to ask because I'm confused, and the answer is probably really simple. How am I to smear the bar of compound from stewmac on the guitar when it's as hard as a brick? I know the obvious answer is to get it wet but water just beads right off the bar, as does any kind of paint thinner. So I just don't know how to get it to spread. I have never used a hard bar of polishing compound. In my experience they have always been clay like.

Thanks for the help,
Dustin

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Dustin:

I think what you're talking about is a compound bar made to use with a buffing wheel on a bench mounted polishing wheel. For those, you turn on the buffer and then let it come up to speed, then jam the bar into the wheel. The speed creates enough friction and it "melts" the bar leaving the compound in the wheel.

The friction thing is why you always want to keep your work moving and DO NOT stop. You'll "burn through" your finish in a heartbeat.

The compounds I used came in a tub. I stirred it up and then applied it onto the foam pad I was using to polish, not on the guitar body.

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  • 1 month later...

I have a few questions:
1. whats the difference between dry sanding and wet sanding
2. when sanding the clear coat, how much presure should i use
3. what TYPE (not brand) of polish should i use after sanding until 1500 / 2000 grit
4. when spraying metallic colours, is it advisable to sand every coat (i read somewhere that sanding metallics affects the
reflective properties)

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1. whats the difference between dry sanding and wet sanding

I dry sanded with 400 and then 600 and I did one going up/down and then the other going left/right. This leaves little scratches in the finish you can see. You use the scratches to check your work. When all of the up/down scratches are gone and all you see are left/right scratches, you're done. I did this to make the wet sanding with finer grit more effective. I used naptha as my wetting agent because I didn't want any water to get to bare wood that may be there and it doesn't hurt the finish or the wood. Wet sanding makes a slurry of your medium, mine was naptha, and the finish you are taking off. I still did the left/right & up/down so I could check progress. The wet sanding in like insurance for you. The wetting medium doesn't let the finish build up on your paper and scratch the finish. You sand a little and then wipe with a soft cloth to check your work, rewet your paper, sand a little, wipe, rewet, sand a little, wipe, wewet. You do this until all of the let's say left/right scratches are gone and all you have are up/down scratches. It's time to move up the the next grit.

2. when sanding the clear coat, how much presure should i use

Very little, if any. I used a Pink Pearl pencil eraser to do mine. I cut the paper so it fit and held the paper to the sanding block, (Pink Pearl), and held the paper to the sides of the block with my thumb and middle finger while resting my index finger on top of the block. No pressure was put onto the block with my index finger, just the weight of it resting on the block was enough. When you start wet sanding, you'll see what I mean when I say this, but the paper digs in. That's a good thing. I think it's the wetting material in use with the sand paper. It kind of pulls your paper into the finish and creates a vacuum of sorts as you sand. That way your paper is in full contact with the blaock and the finish at all times.

3. what TYPE (not brand) of polish should i use after sanding until 1500 / 2000 grit

DO NOT USE A SILICONE BASED POLISH. Other than that, I can't tell you because I don't know. I used the stuff Stew. Mac offers and it worked quite well. At first I thought there was no way it would work. It felt just like toothpaste when rubbed between my fingers and I couldn't tell the difference between the two I used which were medium and fine. As far as what kind to use, search around on the webpage(s) and see what other people recommend. I can say this; if you get the tubs of it like I did from Stew Mac, there's enough to do a bunch of guitars. I did my first one with it and you can't even tell I used any from either tub.

4. when spraying metallic colours, is it advisable to sand every coat (i read somewhere that sanding metallics affects the
reflective properties)

I'm not sure so I'm not going to comment other than this; Unless you have a drip, hair or fuzz or something in the finish, I would say no. I have read, (never done it), that the metallic finishes won't look right when you sand in between. I have also read that you want to put down "wet coats" when doing metallics so they can flow out. Never doing one myself, I'm not going to offer anything else than that because I wouldn't want to steer you in the wrong direction.

After you start wet sanding, the things I've said will make more sense and you'll see what I mean on a couple of my points. I was kind of afraid something bad would happen like it was some kind of black art or something, but it's an easy and effective way to sand your finish.

Hopes this helps!
B-rad

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First day:
You spray once, wait twenty minutes, spray again, wait twenty minutes, and then spray for the third time. Let it dry/cure/gas off for twenty four hours. One coat is done.

Day two:
Spray once, wait twenty minutes, spray again, wait twenty minutes, and then spray for the third time. Let it dry/cure/gas off for twenty four hours. The second coat is done.

I did 48 coats, (I think), but I lost track. It's a bunch. When you sand, you take quite a bit off, especially with the rougher grits like 400 and 600. Once you get up into the 800, 1000, 1200, 1500, 2000 grits, not much seems to be happening but I guess that's what you need to do. Others may disagree on how much sanding, where to start or where to end, and that's fine. All I can say is that they are not the one's who own and play the guitar I made, I am. I wanted to make sure I put enough on so I could sand it seven times, use polishing compound twice, medium and fine, and then finish up with swirl remover. All in all you will see and work on every square inch of your guitar ten times.

A note on that... I think it would be better to have too much on, (it's very thin), than not enough, and find this out some where along the way. I've read quite a few posts where people have had sand-throughs. This is the best way to stay away from finishing, waiting a month before you start sanding, having the sand through problem, having to sand all the way down and starting over.

I've read a lot of posts on this very subject. I've yet to find someone who can say, for sure, that a thick nitro lacquer finish, meaning the thickness of two playing cards changes the sound from a guitar that has a thin finish, say the thickness of two pieces of note book paper. If someone else is reading this that can show me data that says differently, I'd like to see it.

I've read posts of people saying "Oh yeah, it sounds WAY different and thin is much better". Or something like that. Show me data.

If I made ten recordings of the guitar with a thin finish on it, and then layered more coats on the build it up, and then made ten recordings of it, blindfolded that person and played the recordings of the guitar with each one ten times in different orders, I would bet the person who said that they could hear a difference couldn't hear a difference at all.

They want to hear a difference, so they do hear a difference.

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Yeah there is. You can use a stationary buffer morot with a long arbor so you don't ding the body into the motor, but the sponge buffing pads are much cheaper. There are other ways to do it too, look at the Stewart MacDonald website to find out more.

For the edges of my guitar where I couldn't get the foam pads, I use my gloved hand and rubbed and rubbed and rubbed. You can't tell where the foam buffing pads left off and I started with my gloved hand. I rubbed it on a lot though.

Here's a picture of the side where I didn't hit with the buffer but by hand...

[img]http://i120.photobucket.com/albums/o176/J_48_Johnson/Side.jpg[/img]

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is it possible to polish the whole guitar by hand? what are the results like compared to using the proper tools? how can i tell that its time to move on to the next compound and how will i know if i've completely cleaned off the previous compound before starting on a finer one?

Edited by cukaracha
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Fist of all, I think you could polish one by hand, but it would take a long time compared to doing one with a powered buffer.

How to tell... well, I just did it as long as I thought I needed to do, and then did it a little more.

At this point along the way, you're not taking anything off of the finish as you are when sanding wet or dry. You may be taking off a bit, but nothing to speak of.

I would say if you think you're done, and you wipe it all off, and it doesn't look good enough, slather some more on and do it again. Always, ALWAYS use a clean soft cloth when wiping it off. You don't want to scratch the surface you just worked so hard trying to get.

I used terry cloth towels and started by taking all of the heavy spots of compound off first, and then going back and wiping the film off of the rest. After that, with a clean towel, I kind of buffed the whole thing before moving to a finer compound and redoing the steps above... always with a clean towel.

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How long? Boy, I can't really tell you that. I just did it. I guess, about five minutes, maybe a bit more, maybe a bit less, but about five minutes. After that, I rubbed the edges for about the same amount of time with a nitrile gloved hand. After that, wipe all off it off, buff with a clean cloth, and start on the next compound.

As far as any signs, no, I didn't see any signs, I just did it until I felt it was enough.

Let me tell you this though, I did by hand, under the neck plate with a dab of the compound on my finger and just kind of rubbed it in for a few minutes to see what it would look like in a place that wouldn't show. After a couple minutes, it looked pretty good!

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polishing only takes five minutes per compound using hand??!! wow.. i always thought it'd take a lot longer.... well, thx a lot 4 your answers, johnson!! they really helped me understand polishing a lot! i'll be sure to acknowledge you if i ever do a guitar project..

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[quote name='cukaracha' post='334513' date='Jun 16 2007, 08:19 AM']polishing only takes five minutes per compound using hand??!! wow.. i always thought it'd take a lot longer.... well, thx a lot 4 your answers, johnson!! they really helped me understand polishing a lot! i'll be sure to acknowledge you if i ever do a guitar project..[/quote]

Really, really not the case.

Sanding everything level with 2 to 4 grits of sandpaper (starting with 1200 if at all possible, moving up to 1500 or 2000) already takes the better part of an hour or two, and to do a really good polishing job, you're going to need that amount of time again. At the very least.

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