Refinishing Problem

[cukaracha]

So heres what happened. i sanded the clear up to 1500 grit (i had 4 coats of color and 6 coats of clear). by then it looked and felt perfectly smooth. however, it couldn't reflect anything at the time. when i polished it with Perma Glass Polymer Sealant, it started so shine and reflect. the thing is, now i can see a lot of scratches all over the body. and it doesn't shine like how it should. instead, its only slightly shiny.

what did i do wrong and how do i remedy this?

thanks in advanced.

[Muzz]

Just one more step to include, 2000 grit, then cut and polish, then you will be on the home stretch.

[cukaracha]

ok. i resanded the body with 1500grit (i couldn't get any 2000) until i thought it was completely free of scratches. however when i polished it, i saw that the entire body was covered in very fine scratches. will these go away with more buffing or should i do something else?

[Muzz]

To get the 2000 grit go to a car spare parts shop, they will have it or get it in for you. This will get a significantly flatter micro surface for the cutting compound to gloss up.

[cukaracha]

i'm not so sure that its the sanding thats the problem. this guy sanded his with 800 grit and it turned out just fine... are you sure its not some other problem? possibly with the polish i'm using or something?

[guitar2005]

i'm not so sure that its the sanding thats the problem. this guy sanded his with 800 grit and it turned out just fine... are you sure its not some other problem? possibly with the polish i'm using or something?

Actually, No... From that page:

"After the dry 800-grit sanding I switched to wet-sanding with 1200-grit Unigrit™." Then, later on, "To rub the finish out, I started with our #1201 Coarse on a Foam Polishing Pad mounted in my electric hand drill. Here I have switched to the #1202 Medium compound on a separate foam pad"

then he finishes up with a fine compound. And Keep in mind that he's working with nitro lacquer which is relatively soft so the buffing process removes some scratches too.

Edited November 29, 2007 by guitar2005

[Drak]

Your problem is most likely your inexperience with the wetsanding and buffing process and has nothing to do with any product selection.

It is a common problem with first-timers, and that problem is that as you progressed up in your grits, you did not get all the scratches out from the previous grits, so the scratches you see are probably some 500 or 800 grit scratches that did not get worked out as they should have.

This is perfectly normal for a first time finisher, and is just part of the learning curve involved in learning how to do a good rubout. I have no idea why so many people think this stuff is so easy that everyone is going to get it perfect the first time, because I sure didn't.

Your answer is to start over, go back down to a lower grit, maybe 500 or something, and start all over again, this time spending a lot more time with each grit before moving ahead.

I HIGHLY recommend for first time finishers that they relegate 1 time period to 1 grit and stop there for the day, or for the afternoon, with a break between grits.

This makes you spend the proper amount of time and ATTENTION to that particular grit.

Treat every single grit stage as if it was the ONLY grit stage you were doing.

What commonly happens is that you have worked so hard at building the guitar, you're coming down to the final stages and getting very exited, and you start to RUSH the sandout stages, and wind up leaving scratches from your previous grits in the finish because you ran up the chain of grits too quickly.

No worries, it happens to a lot of people, and is normal.

The only other piece of advice I can give is to use the old trick of sanding one way for one grit, then cross sand the next grit, so you will SEE if there are any scratches left before you move up to your next grit.

So lets say you sand across the body with your 500, then you sand WITH the body to do your 800. You will do the 800 until when you hold it up to the reflected light source, you see NO scratches going across the body, then you will KNOW you removed ALL of your 500 grit scratches before moving up to your 1000 grit, at which point you will go back to sanding ACROSS the body again, untill all of your 800 grit scratches going WITH the body are completely gone.

You do not proceed to the next grit until all of the scratches from the last grit are all gone.

The danger here is how thick is your clear coat stage?

If you have to keep repeating yourself because you left scratches as you moved up, the more times you have to start over, the more chance you're going to cut back into your color coats, so as much as I know a lot of people want to get it done by this point, it really doesn't pay to hurry the finishing stages, you can ruin the whole thing very easily here just by rushing it.

[uv777]

wow. drak that was very informative. thank you for that!

[jmrentis]

Agreed, excellent and helpful info Drak!

[cukaracha]

yep. really helped. thanks for all the replies!!

Cheers

[Drak]

No problem, best of luck to you.

The only thing I can add is to go really really lightly around the edges, at all stages.

ESPECIALLY when using the coarser grits. If you put some really deep 500 grit scratches into your edges, you may run out of clear coat trying to chase them out with the upper grits and wind up sanding right into your color coats, so you gotta be really careful around all your edges.

You can just as easily get your edges nice, and then, at the very last stage, burn thru your edges with your final buff outs.

Watch those edges.

I remember when I finished one of my first guitars I was quite pleased with myself ( ), because it came out quite beautiful (so I thought).

...Until I took a few pictures of it. I took some inside pics with flash, and when I looked at the pics, there were a THOUSAND scratches going all through the finish that I really never saw that the flash had captured, until I held it up to the light and looked closely at it, and damn if they weren't there .

I just didn't know to look closely after every grit stage to make sure I got everything, and I had done exactly what I described above, left a ton of scratches from previous coats as I worked up.

I simply hadn't done it enough to know what to look for, to know what to do to make sure it came out correct, to get really good at it yet.

All these things take repeated efforts to get progressively better and all have learning curves built into them.