Problems when sanding the clearcoat.

[jzeilon]

So..

I have some problems when i,m doing the last thing on the paint job for my soloist body.

After spraying something like 10 layers of clearcoat (thin with spraycan) and letting it rest for 5 days to cure i yesterday started to wetsand.

I almost right away got the feeling that i sanded through the clearcoat. The reason is that it looks like the pearl effect is getting less pearl,  :icon_scratch:

I do have the orange skin effect that i guess is the clearcoat?

How can i be shure that i,m not sanding to much? The surface looks worse then before i started to wetsand  ???

Thanx for some advice

/JZ

 

[anorakDan]

10 coats might be enough, or maybe not. You just may sand through them, depending on grit, how wet you keep the sanding and how hard you sand.

There is ALWAYS orangepeel on a sprayed finish. It's the nature of the beast. Unless you use something that is very self levelling. Like Future floor finish. (Which, I don't really recommend for a guitar, but you could use it. It gets very glossy, tough, cheap, readily available and requires no sanding.)

When you're sanding a glossy paint to make it glossier, it will always look dull. It will look dull all the way up through to the 12000 grit of a polishing kit like Micromesh's. You task it to make the project equally "dull", consistent over the whole project, before you move on to the next finer grit.

If you have a true pearl or metalflake finish and you hit the pearl layer, you'll now it. The pearl is a rougher grit than your sand paper and will leave visible scratches. You see these, stop. dry the project off and spray more clear.

It's always a good idea to start sanding or polishing on a part of the project that isn't highly visible, like the front. Our first instinct is to start with the front and carry on from there, but  there is always a learning curve in any task, so leave the visible stuff until you've got your skills "polished."

On the positive side, if you have sanded through to your pearl layer, shoot some more clear. If I knew I were polishing a painted finish to a high gloss, I would clearcoat the living bejeebers out of the project, knowing that I will be removing a lot of the clear as I sand it away. Your top coats should visibly flow onto the project while you're painting. Then let that sucker outgas for days. Start your sanding with the rougher grits, work in the same direction for each grit, but turning the sanding pattern 90 degrees each time you advance to the next finer grit. Make sure you clear the sandpaper and sanding surface with the water a lot. You'll develop a "feel" for the task as you move along the project. Also, use a light touch. Let your sandpaper do the work, not your arm muscles.

Finally, as someone who has painted and polished a lot of projects, don't allow yourself to become afraid of working the project. you can always re-spray a problem area and work it down. Finish sanding and polishing is a zen task. Patience, consistency, and confidence.

Good luck and shoot some pictures for us!

 

[jzeilon]

Thanx!

I,ll just keep sanding it real careful and so on.. If for some reason it looks like shit.. i,ll just sand it to bare wood again and starting over..  :evil4:

I,ll post some pics real soon.

Thanx again for the support.!

/JZ

 

[dmraco]

did you sand the paint before the clear was added?  Not sure what type of paint you are using but I have always sanded down the orange peel on the paint, then cleared.  The re-sanded and buffed.  That was using automobile paint (house of Kolor).

depending on your sanding menthod, you may have gone thru.

 

[Jusatele]

you want to do an uber job?
practice on some other piece of wood, yep go to a cabinet maker and see if he has a 1 foot  piece of scrap with a hard wood veneer on it. tell him what you want it for and he may give it to you free.
Now seal it,sand it, paint it, clear coat it and sand that, you will be getting a lot of feel practice without ruining your project.

I really suggest anyone try to do finish work on practice pieces first, why ruin a 200 dollar piece of wood by not knowing what you are doing, we already have enough of those bodies on Ebay with out our members supplying more

we need a sticky in the Finish department telling everybody to practice on non project wood

Hope this helps

 

[leo12.]

What 10 coats did you spray? nitro, precat, poly, other,? on what colour you memtion pearl, is it a pearl finish with 10 coats of clear?
5 days i think is to soon for cellose, wet sanding should bring you close to rubbing out not for removing orange peel . more details

 

[jlegnor]

What 10 coats did you spray? nitro, precat, poly, other,? on what colour you memtion pearl, is it a pearl finish with 10 coats of clear?
5 days i think is to soon for cellose, wet sanding should bring you close to rubbing out not for removing orange peel . more details

That's what I was wondering.  If you're using Nitro in spray cans, the normal waiting period before any kind of wet sanding or buffing out is at least 28 days or so.

 

[AtoZGuitars]

I use Urethane base automotive paint on everything.  But I own a body shop so I could talk for hours about sanding and buffing.  Putting 10 coats of Clear is a bit extreme.  On a paint job that I have really big layers and custom artwork I will put 3 coats of clear at most.  Anything above that is just overkill and you are asking for more and more dirt inbetween layers (especially if you dont have a proper back or downdraft booth that will avoid overspray).  I agree with what  a lot of the guys are saying in that it will look dull after you wetsand but obviously will shine up after buffing.  You can absolutely get rid of Orange peel also by sanding with a flat block to knock down that texture (again being careful with how far you sand).  And like someone else said you will definitely know if you went through to the pearl coat.  It will look like garbage.

Spray cans are fine to use because they are affordable and available but if you ever get the chance, use automotive paint.  Waayyy better results and more durable.  Its also a little bit easier to control an HVLP spray guy than it is a spray can.  The only down side is you need to buy an air compressor and the gun.  Worth it.

 

[Cagey]

If you use urethanes, I can see where you wouldn't put numerous layers of clear on. But, lacking the proper setup to do urethanes most DIY guitar finishers use lacquer, so there's the lack of heavy build-up, inevitable losses due to the vehicle boiling off and level sanding between coats. Still, you're probably right in that more clear gets shot than necessary. Luckily, lacquer is both forgiving, easy to shoot, and easily repaired if things don't work out well.