Gloss black - what primer/undercoat

[profchris]

I'm making myself a resonator ukulele. The top will be mainly a chrome cover plate, and the fingerboard will be white pearl celluloid (known as Mother of Toilet Seat in the fraternity). So of course, I need to paint the body gloss black. The body will be birch ply.

I've done something similar before, using shellac to seal the ply, spraying black automotive paint, wet sanding to level, and then two or three coats of Tru Oil on top. This looks good from a distance, reasonably OK close up.

Any suggestions for getting a higher quality gloss black finish? I'm guessing the secret is in the primer and/or undercoat, but I am remarkably ignorant about painting.

The finish needs to be fairly thin, but not at the "only measurable in microns" level.

 

[marcros]

black dyed shellac, over black dyed wood? i have only done it once as an experiment but it looked good.

 

[n0legs]

If it was me, I would sand and seal the plywood.
Find the highest build primer I could safely use and apply a few coats.
Sand it back with a 320 grit paper. Apply 2 more coats of primer, then flat this back with a 600 grit paper.
I would then use a "guide coat" over the primer. Allow the guide coat to dry then flat it back with a 600 grit again. If there is any "guide coat" left in the hollows I would apply another few coats of primer.
"Guide coat" once again and flat back, if at this point all the "guide coat" has gone I would go to a 800 grit paper. Flat the whole thing then move onto my finish coats.
Apply a few coats and allow to harden/dry, de-nib the finish coat with 1200 then paint my final coats.
Allow the finish to harden/dry, then flat back with 1500 then 2000 grits.
Get a decent polishing compound and hand polish the finish. Remove all traces of the polishing compound, then apply a good quality wax. Buff to shine and enjoy.

 

[profchris]

Marcros - black dyed shellac is tempting, as I'm used to finishing with shellac. Dyed with? Lamp black? And is it translucent or solid black?

Nolegs - any particular kind/colour primer? I'm familiar with the coat/sand/repeat process for finishing with clear, and with pore filling.

 

[marcros]

i used a wood dye- transtint, but you won't be able to get hold of that one.

it was a solid black, but I am not sure whether that was the black shellac, or because i had dyed the timber beneath.

 

[n0legs]

Nolegs - any particular kind/colour primer? I'm familiar with the coat/sand/repeat process for finishing with clear, and with pore filling.

I would use U-Pol primers, spray cans, for ease. Excellent products.
They are around a mid gray in colour.

 

[profchris]

Thanks guys.

I'm going to try dye with shellac - http://www.ebay.co.uk/itm/131021751221

Will report back.

 

[Kalimna]

This might be the stuff that would work well. There is a fair bit to spraying well, but a bit of practice on test pieces will help. I've used their translucent nitro cans on a uke before and the end result wasn't bad at all.

http://www.manchesterguitartech.co.uk/p ... r-aerosol/

Adam

 

[ED65]

I've done something similar before, using shellac to seal the ply, spraying black automotive paint, wet sanding to level, and then two or three coats of Tru Oil on top. This looks good from a distance, reasonably OK close up.

Any suggestions for getting a higher quality gloss black finish?

I think you were halfway there to a very nice job and then took a step back by what you put on top. Automotive paint is capable of much higher gloss than a product like Tru-Oil can give, and additionally it is far harder so will hold up to wear better.

You could just buff up the paint to a gloss once you have a sufficient build to flat off, then polish using T-Cut or the like, but if you want a clearcoat on top of the black for added protection then some kind of lacquer would be infinitely preferable to an oil/varnish blend like Tru-Oil.

 

[profchris]

I've done something similar before, using shellac to seal the ply, spraying black automotive paint, wet sanding to level, and then two or three coats of Tru Oil on top. This looks good from a distance, reasonably OK close up.

Any suggestions for getting a higher quality gloss black finish?

I think you were halfway there to a very nice job and then took a step back by what you put on top. Automotive paint is capable of much higher gloss than a product like Tru-Oil can give, and additionally it is far harder so will hold up to wear better.

You could just buff up the paint to a gloss once you have a sufficient build to flat off, then polish using T-Cut or the like, but if you want a clearcoat on top of the black for added protection then some kind of lacquer would be infinitely preferable to an oil/varnish blend like Tru-Oil.

The Tru-Oil was a bit of a bandage - I was building to a deadline and running out of time, so couldn't spray more coats, level, buff etc. Over an incompletely level black finish, Tru-Oil's soft sheen disguises the irregularities and looks pretty decent.

I might still use it on this one for two reasons - first, the soft sheen is possibly more attractive than a full gloss shine for this application, and will help the shine of the chrome cover plate stand out in contrast, and second, repairing nail scuffs from strumming is a 10 minute job with Tru-Oil.

Or I might do it right - I suspect a lot will depend on how urgently I need to play it as this one is for me.

 

[profchris]

This is how it has turned out so far - not too bad, but I intend to strip and redo it as explained below.

The black dyed shellac gives exactly the effect I wanted with Tru-Oil on top - a decent gloss sheen, but less glossy than the chrome cover plate or Mother of Toilet Seat fretboard, so that these stand out. From a few feet away it looks great, up close you can see the problems.

1. My surface prep wasn't good enough. I'd expected the shellac to build so as to fill the slight defects but it didn't behave as normal - I suspect the dye to have been the cause.

2. The shellac didn't harden as fast as normal, so when I sanded back I went through in spots.

So I shall make up a test piece. After sanding, I'll dye the wood, resand, redye, until I have a good surface, uniform black. Then I'll apply undyed shellac, allow to cure, and level. Next dyed shellac, leaving twice the cure time and levelling very delicately. Finally, Tru-Oil on one half, polishing and buffing the shellac on the other, to see which I prefer.

If neither works well I'll go to automotive paint, following Nolegs' method. I can see that will produce a good result, though maybe more high gloss than I discover I want.

None of this is essential as it plays and sounds rather well, and the audience won't see the flaws. But I know!