spraying guitar disaster :-( ,advice?

ClockWorks

Hi guys,after spraying on primer, I applied the colour coat which has now started cracking(crocodile skin look) ,can i sand these out and re-colour? Or am i buggered and need to sand back to primer? (then re-prime re colour etc) ,from the interweb I think I didnt leave the primer long enough to dry before i painted(not enough patience)
Any help appreciated.

kevin65

Are you sure that the primer and topcoat used are compatible?

ClockWorks

Yup,their both halfords acrylic.

kevin65

Well, I guess the only other reasons could be:
(1) Some sort of contaminant on the primer or leeching through the primer
(2) Insufficient drying time for primer as you said
(3) Problem with the topcoat applied (unlikely, if you overcoat you just get runs)

If you think that the problem is down to insufficient drying time, then you need to leave the top coat to harden properly(a week at least) so you can wet sand it down to a decent base to re-apply the topcoat again. If the paint isn't properly hardended when you sand, you will make a b*lls of it. A so called 'professional' on one of the other forums would strongly disaggree about the drying of acrylic paints, but while the paint surface dry fairly quick, it takes a while for it to harden through the entire coat.

If you're not in a hurry, wait for paint to harden and then wet sand a portion of the back and apply some top coat to this. If this is successful, then wait for this to harden and wet sand the whole body and respray.

ClockWorks

Would the prefered option be to wait the week then sand(800 grit) the existing top coat and recover,or sand off the top coat altogether re prime and recoat ?the material difference will be a can of primer ...

Owen

That crocodile skin texture happens when there's too much paint applied in one go. The thinners in the single pack (Aerosol) paint try to pull the coat flat, and when there's too much, it cracks up like the surface of a desert. It happens with spray gun paint too when there's too much thinners in the paint, or if it's applied too thickly.

All you can do now is rectify the finish by sanding off the paint with a block (Don't do it by hand or you'll get a rippled surface that will be impossible to see but will be spotted a mile away as soon as you put paint on) and some 800 w&d. Degrease with a proper pre-paint solution, reprime, flat the primer with the 800 and block again, degrease with pre-paint, and dust on the lightest thinnest coats of paint leaving 15 minutes between coats. It'll take a few hours to build up enough to cover the body of the guitar (8 paper thin coats will take 2 hours) and at that point you'll be ready for clear coat.

Owen

Don't worry about waiting a week for the paint to dry, this isn't 1960. The paint will be dry after a few hours regardless of weather. You'll be able to sand it back tomorrow.

If you could do it, you'd be better off getting someone to prime the body for you with 2 pack high build polyester primer. It's a concrete hard layer of paint which will also give you some thickness and smoothness to counter the wood's natural tendancy to let the texture of it's grain come through. I've sprayed 2 strats in the last few years and it's vital to have a stable primer base.

However, the reaction you're describing above has nothing to do with primer, only putting the colour on too thick at a time.

Owen

kevin65 wrote: »

A so called 'professional' on one of the other forums would strongly disaggree about the drying of acrylic paints

That'd be me. And you're still wrong. Paint dries a lot faster than a week without assistance. I still can't believe you're sticking to that claim. I had an entire back panel of a Mini Cooper primed, painted and lacquered in a day this week, and after 1 day of letting it sit overnight with no heat, no oven, it was dry enough to flat and polish today.

ClockWorks

Hi Owen ,If Im getting this right....
Sand the cracked crocodile looking finish flat using 800 grit..
Re prime (over the now sanded paint)
Then recoat at the intervals specified....

eoin5

By any chance was it quite cold while you were spraying? The weathers been all over the shop lately. That can cause problems.

btw Owen are you in the mini club?

Owen

ClockWorks wrote: »

Hi Owen ,If Im getting this right....
Sand the cracked crocodile looking finish flat using 800 grit..
Re prime (over the now sanded paint)
Then recoat at the intervals specified....

Pretty much! When sanding with 800 use plenty of soapy water to aid the process, but you must use some sort of panel wipe in between. If you don't have any I've a bit at the bottom of a drum here you can have.

eoin5 wrote: »

btw Owen are you in the mini club?

Sure am!

kevin65

@Owen - we'll agree to disagree:)

@Clockworks - when wet sanding, keep in mind that you don't want to over wet the timber, and give it plenty of time to dry before re coating. Best of luck and post some pics when finished.

ClockWorks

Ok Iv sanded it back to bare wood with 400 grit and lots and lots and lots of sanding, Im going to give the whole lot a sand with 800 grit and prime ,have I missed something or am I ok to drive on....

Owen

You need to remove any sanding debris now, especially surface dust. It'll be hard to see it, and even if you wipe it with a cloth you'll only be getting about 75% of it off. If you have access to compressed air give it a right good blowing (Ooooer Matron).

Little tip about painting a guitar, dust falls vertically. If you want to get the best finish, hang it by the holes where the neck is bolted on. You drastically reduce the surface area the dust can fall on.

400 grit paper is harsh enough, you'll have a lot of sanding marks from it. I'd probably do it all with 600 w&d next to get those out, let it dry, pre-paint wipe it, then build up dust coats of primer until the aerosol had been fully emptied. Leave it dry for a few hours, then wetsand the primer with something like 1200 w&d, wipe with pre-paint, and build up dust coats of your base colour. Leave that dry, and don't sand, then just as it's all dry, dust on one final coat of colour to provide adhesion, leave that stand for 15 mins and lacquer.

ClockWorks

Iv a hanger made up for it alright, ill give it a good sand with 600 grit(then a sand with 800?) ,I do have access to a compressor, Ok to sand out any marks I find inbetween primer coats or should I wait till I have a can worth on and add a few more coats of primer then..,same with dust etc picked up between colour coats...Ill add pics as a I go.
Cheers.

ClockWorks

Opps ,1 more thing ,any water involved in the 600/800 sanding before primer?

Owen

Always, even though w&d paper can be used dry, it fouls up after only a few passes. Plenty of soap in the water to aid the movement of the paper too. But as Kevin said you must ensure it's bone dry before painting.

Routine I'd go with is :

Clean surface for paint
Prime in dust coats, build up as much as you can
Sand with w&d 800/1200 and water and a block, get it as smooth as possible.
Dry & Degrease with panel wipe
Base coat in dust coats, build up as much as you can here too, slow even passes to prevent any striping
Lacquer. The hardest bit. There's no advice I can give you here if you're doing this with an Aerosol, it won't be great unfortunately.

ClockWorks

Cheers Owen,I know Im probably asking some real newbie questions but I want this to be last attempt ,and I really do appreciate your effort and patience with me :-)

Owen

No prob dude, Ray helped me EQ out my bass rig a few weeks ago, so this is karma payback

Celly Smunt

stain it :cool: