Hi! I almost finished my guitar and I'm looking for solution to avoid cracks on painting near joints (between neck/ fretboard, neck/ body, body pieces). I want to do black solid finish on mahogany, polyurethane probably. I read about epoxy resin grain filler and it sounds good but I heard it's god way to do cracks on paint. Is it true? Do you have good idea for that?
How to avoid paint cracks?
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ARandall
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Well, some finishes do better than others in that regard.
But if there is no gap there to fill, then there is little that any form of grainfill (or filler fullstop) is going to do. Indeed grainfill does nothing to stop the joint cracks, as it is there merely to stop the finish products sinking into the larger pores.
The main issue really, is that wood moves over time, and the only way you can minimise it is to effectively guess the bits that are going to move in sympathetic ways......or laminate so that as one bit pulls one way, another is resisting.
A flexible sealer coat might also help.....but you need to make sure its compatible with the top coat.
But if there is no gap there to fill, then there is little that any form of grainfill (or filler fullstop) is going to do. Indeed grainfill does nothing to stop the joint cracks, as it is there merely to stop the finish products sinking into the larger pores.
The main issue really, is that wood moves over time, and the only way you can minimise it is to effectively guess the bits that are going to move in sympathetic ways......or laminate so that as one bit pulls one way, another is resisting.
A flexible sealer coat might also help.....but you need to make sure its compatible with the top coat.
B. Howard
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First this is dependant on the quality of the joinery. Good tight fitting joints that are properly glued exhibit no movement between pieces which is a large reason for these cracks. The two pieces simply move slightly independent of eachother and no finish hard enough for a guitar is flexible enough to handle major wood movement.
Next up is controlling the amount of build or filleting in inside corners at the neck joints. Most finishes have a maximum working thickness. 2K polyurethane is typically 5 mils. Exceed that in the corners and they will crack because the film is too thick which makes it brittle.
Choice of grain filler will have very little to do with this.
Next up is controlling the amount of build or filleting in inside corners at the neck joints. Most finishes have a maximum working thickness. 2K polyurethane is typically 5 mils. Exceed that in the corners and they will crack because the film is too thick which makes it brittle.
Choice of grain filler will have very little to do with this.
emoney
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If your joints aren't as close as you'd like, it might be wiser to search for a finish that's easily repairable...kinda like Nitro.
While no one can tell the future, the movement of wood these two wise contributors have shared is pretty much inevitable in the right situations. Don't forget, "cracks" are where stress escapes and you don't want a guitar with a bunch of built up stress inside, anything could happen.
While no one can tell the future, the movement of wood these two wise contributors have shared is pretty much inevitable in the right situations. Don't forget, "cracks" are where stress escapes and you don't want a guitar with a bunch of built up stress inside, anything could happen.
Thanks for all replies!
That's how my neck joint looks:
Space between is about 0,1-0,2mm. I tried my best but I can't do it more tight.
I never used polyurethane and nitro paint for guitar. I painted previous guitars with acrylic paint but it's to soft. I read that nitro likes to cracks if it's badly done.
That's how my neck joint looks:
Space between is about 0,1-0,2mm. I tried my best but I can't do it more tight.
I never used polyurethane and nitro paint for guitar. I painted previous guitars with acrylic paint but it's to soft. I read that nitro likes to cracks if it's badly done.
Daniels Guitars
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No where near good enough imo, you need to do more work to close the gaps right up
emoney
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I agree, you CAN get that joint tighter as it looks relatively straight. Because of that, Peter's recommendation of pulling sandpaper through should help a bunch. Pull the neck out, put the paper in, put the neck back in. It's not an immediate solution, but it's the best one. Take your time.
As a side note; ever noticed how a lot of set neck guitars come with a darker finish at the neck-to-body joint and then usually the back of the headstock? That's an old factory trick to cover up those crappy joints.
As a side note; ever noticed how a lot of set neck guitars come with a darker finish at the neck-to-body joint and then usually the back of the headstock? That's an old factory trick to cover up those crappy joints.
fatdaddypreacher
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again try you must, young swisher, do you can.
cmjohnson
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My standard finish is DuPont (now Axalta) Chromasystem acrylic urethane. Honestly I'm not much of a fan of nitro lacquer and once I went with Chromasystem, I knew I'd found my answer. With care it can be applied as thin as a nitro finish, not damp body vibrations, and will last a VERY long time. And no checking! Some people would consider that to be a negative, but I'm not one of those people.
