Can I Wait Too Long To Polish?

[stratoskier]

Greetings,

I recently finished applying the clearcoat to a body I've been working on. I've been following the directions found here in the tutorials and forum threads, but I'm concerned about blowing it at the last step. The body looks pretty good except for some minor orange peel and some areas that don't appear to have as much gloss as the surrounding areas. Basically, I'm terrified that I'm going to screw it up when polishing.

My first question is this: In the threads, some people have talked about letting the clear coat cure for a month or more. However, the can says to apply a rubbing compound after 48 hours. So... is it possible to wait TOO long to polish? I was planning on giving it the full month, but now I'm wondering if that might not be a good idea. I read somewhere that the heat generated by polishing can help a partially-cured lacquer to smooth out.

2nd question: I've come across a lot of conflicting thoughts on what grit sandpaper to use for final finishing and polishing. ReRanch says to go all the way from 400 up toi 2000 before polishing. But here, I found some threads that said anything lower than 1200 would remove too much clearcut and/or cause fine scratches that would be nearly impossible to remove. I assume that some of these different opinions result from different paint types (lacquer vs poly, etc.), but it's not always clear from the threads what paint type is being referred to. Because I'm petrified of messing it up by going through to the color coat, or causing scratches and imperfections, I'm inclined to start very fine (1000 to 1200). If anyone could help to clarify what grit to start with for this Duplicolor acrylic lacquer, I'be be grateful.

Thanks!

Bert

[Foggy]

Greetings,

I recently finished applying the clearcoat to a body I've been working on. I've been following the directions found here in the tutorials and forum threads, but I'm concerned about blowing it at the last step. The body looks pretty good except for some minor orange peel and some areas that don't appear to have as much gloss as the surrounding areas. Basically, I'm terrified that I'm going to screw it up when polishing.

My first question is this: In the threads, some people have talked about letting the clear coat cure for a month or more. However, the can says to apply a rubbing compound after 48 hours. So... is it possible to wait TOO long to polish? I was planning on giving it the full month, but now I'm wondering if that might not be a good idea. I read somewhere that the heat generated by polishing can help a partially-cured lacquer to smooth out.

2nd question: I've come across a lot of conflicting thoughts on what grit sandpaper to use for final finishing and polishing. ReRanch says to go all the way from 400 up toi 2000 before polishing. But here, I found some threads that said anything lower than 1200 would remove too much clearcut and/or cause fine scratches that would be nearly impossible to remove. I assume that some of these different opinions result from different paint types (lacquer vs poly, etc.), but it's not always clear from the threads what paint type is being referred to. Because I'm petrified of messing it up by going through to the color coat, or causing scratches and imperfections, I'm inclined to start very fine (1000 to 1200). If anyone could help to clarify what grit to start with for this Duplicolor acrylic lacquer, I'be be grateful.

For starters, don't worry about waiting too long before you start polishing, generally the problems can arise when you try to start polishing too soon and before the lacquer has fully cured. If you're polishing out with a mechanical polisher, yes the heat generated is a factor in the polishing process with polishes designed specifically for that use, but only once the lacquer has fully cured. This takes different lengths of time depending on the finish - with 2k lacquers I like to leave the final lacquer coat for - where possible - for at least a week before final rubbing down and polishing, but even after this stage there is a noticeable change in the feel of the lacquer (it's hardness and resistance to minor scratches and scuffs) after a further couple of weeks. So as far as I'm aware, leaving the finish too long before rubbing down and finish polishing isn't an issue, but an advantage.

Regarding grades of wet and dry to use, well if my final lacquer coat was so rough as to necessitate a 400 grit wet and dry, I'd be rubbing down and relacquering it as it's not what I'd be looking for as a final lacquer coat. The final lacquer coat should be pretty smooth and blemish free from the gun (with the possible exception of the odd minor dust specs), as it dries. Ideally it should be a good enough finish to start working from 1200 grade wet and dry, on to 2000, before cutting back and finally polishing. Obviously this is in an ideal situation and using a gun to shoot the lacquer (not a can), but still, if the finish was that rough to need that level of rubbing down, I be tempted to rub that lacquer coat down and reapply another coat until it went on smoother.

I'm sure others will chip in here and like I say I can't speak for types of finish I've never personally used, but hopefully this might help allay your fears slightly

Edited September 4, 2008 by Foggy

[ihocky2]

400 is way too aggresive in my opinion. You can use it, and you can remove the scratches from it, but 400 cuts so fast that it makes it very easy to sand through. My last two builds I started at either 1500 or 2000. It went pretty quickly. If you want to get it level fast and then work up, I would start around 800 or 1000. The idea is to use the finest paper possible so you have less chance of deeper scratches. If you can start at 2000 it is great, because those are very easy to remove, but if you need to do some average leveling, 800 or 1000 will save a lot of time, and is still easy enough to remove scratches.

[killemall8]

i dont believe you can wait too long to polish. the longer the better really. the 48 hours probably means thats the soonest you can polish. as for grits, depends on what kind of finish and how many coats. i dont think 400 is to coarse. i have used 400 many times and it worked fine.

[pariah223]

did you use behlen instrument lacquer by any chance?

[stratoskier]

Thanks for all the responses. I definitely won't go any lower than 800, and will probably see how I do starting with 1200 first. It's also good to know that I can give it some more time before polishing.

Pariah223 -- the lacquer I used was Duplicolor "Truck, Van and SUV" acrylic lacquer in a rattle can. Probably not the finest stuff, but it seems to have worked well for me. I only paint about 1 guitar every couple of years, so I haven't made the move to a good spray gun yet.

Take care,

Bert

[avengers63]

I'm sure that lacquer is just fine. Some folks here use automotive color & clear all the time without any issues. Just show off some pics when you're all done.

[pariah223]

Ah i have never used lacquer out of a rattle can, but i have used automotive clear on a couple of guitars because i work in a body shop, so it was readily available and free and both guitars are still holding up just fine.

[guitar2005]

I used duplicolor clear for my Polka Dot Rhoads V. I think I put 14 light coats on.

2 years later, the finish is still soft, dents easily and when I play iit on my lap, the jean's fabric make an impression into the finish. I called Dupli Color about it and they were surprised I put on so many coats on, that's all. Anyways, I'd stay away from this stuff.

I'm making a new neck for the Guitar. When I disassemble it, I'll try to remove as much clear as I can without going through the white dots.... but doubt that the results will be any better.

As for grit, I would never start below 600 grit.

Can you wait too long before the polishing process? No.

Edited September 5, 2008 by guitar2005

[Southpa]

There is no such thing as waiting too long. Yes, the finish cures and becomes harder to cut with sandpaper, but you will also have more control in your efforts. I've blasted through more dye, stain, lacquer, enamel and poly finishes than I would care to admit, its all part of my personal learning curve. To dwell on those past mistakes would make me a very bitter man indeed.

MY prescription would be to "get it right the first time", naturally. That means ensuring you don't screw up during ANY stage of the process. Use lots of finish but don't get greedy. I've worked alongside some top knotch painters and I envy their skill at laying down an enormous amount of paint at one time and still managing to avoid getting a case of the runs! I just finished my truck, did all the bodywork, filling, priming and sanding myself and then got my buddy from work (the REAL painter) to shoot the topcoat. I'm real happy with the results. I looked at it like it was just a big guitar!

http://www3.telus.net/Alsplace/Truck/

That took me 8 days and cost me about $400 (I have friends who helped with the supplies and materials) The paint (hugger orange and white) is Imron Polyurethane enamel, single stage high gloss, covering urethane enamel high build primer which is covering non-sanding epoxy primer. They use the stuff for boats mostly, hard as a rock, man!

Sometimes you can get away with not having to do any wetsanding at all. I did a maple tele a while back in clear Minwax high gloss poly, rattlecan stuff. Aerosols have high solvent content so the paint is thinner and can be aspirated easier with less pressure. OK, so it takes longer to dry and will shrink more due to solvent evaporation. The good thing is that the stuff will FLOW! After levelling the body of the tele I shot a mirror finish on the front and back. Just shoot the hell out of it and then leave it alone.

To wetsand you first have to assess the nature of what you are wetsanding. Remember the fingernail test. Drips, sags and any other major protruberances should be carefully cut off with a razor while the finish is partially cured. Orange peel can be mild or severe. If its severe then you are best to get a little medeivel with some coarser grit, otherwise use nothing coarser than 800 on the flats and 1200 on corners, and thats going lightly. Let the paper do the work, ie. very light hand pressure and don't sand too fast. Constantly monitor your progress, be VERY thorough and don't skip steps. I use rigid blocks for the flats and sponge pads for the curves. I polish with Meguiar's after 2000 mainly because I can't buy anything finer off the local shelves.

Edited September 6, 2008 by Southpa

[stratoskier]

Wow -- more great tips! I appreciate it!

Southpa -- love that truck. I have a soft spot for old GMC's.

Bert

[ihocky2]

If you really want to see tha quality you are up against go to any music store and look at the finishes on any of the big name brands. A little time and patience and they are not hard to beat. My first guitar came out better than a $700 Fender Strat as far as flatness and polishing. I sprayed it with a candy color and that is where I lost it. My wife has only ever seen the guitars I have built up close and my Squier strat, when I went to get strings last time she looked at the Fender and pointed out to me how much flatter mine get. All it takes is patience and elbow grease. There really is no magic in the big name guitars other than marketing and CNC to make them so big.

[Foggy]

If you really want to see tha quality you are up against go to any music store and look at the finishes on any of the big name brands. A little time and patience and they are not hard to beat. My first guitar came out better than a $700 Fender Strat as far as flatness and polishing. I sprayed it with a candy color and that is where I lost it. My wife has only ever seen the guitars I have built up close and my Squier strat, when I went to get strings last time she looked at the Fender and pointed out to me how much flatter mine get. All it takes is patience and elbow grease. There really is no magic in the big name guitars other than marketing and CNC to make them so big.

Couldn't agree more, it's all about patience and being very, very particular about what your doing.

The only other thing I'd add to everything that's already been written in this thread is the importance of a really good light source when your rubbing your clearcoats down, whether it be natural light from a window opposite your work bench, or an adjustable electric light over your work. A good light source will easily show up any shiney indentations or minute hollows in your finish while your rubbing down and helps to achieve that perfect finish.

Jim