Buffing polyurethane

[vinnydbass]

I'm finishing a fretless with polurethane, ive done it before with great results. Does anyone have any advice for buffing for a glossy finish?

[SurferJoe46]

In days past I've used Black Magic first and maybe a swirl remover and a cotton hood.

Lately I use cornstarch and pure talcum powder and a 10" poly wheel at 300 RPM.

After that a solid carnauba paste wax at 300 RPM on a clean terry head. Repeat every other day for a week and it's done.

IF YOU CAN SMELL the urethane out-gassing - wait longer before buffing.

Just for my own interests I'm trying a no-buff color and poly clear coat on an old guitar. Pixs later if it turns out more the 60% OK.

[Rocky McD]

If you have done it before, what type of buffing equipment did you use then? Poly is more difficult to buff because it is tougher than Lacquer. A large Arbor buffer is probably best, but you could make do with smaller types. I use doubled 8" buffing wheels mounted in my drill press and run it at about 800 rpm. The smallest would be the foam pads made for hand drills.
Rocky

[SurferJoe46]

Originally Posted by Rocky McD

If you have done it before, what type of buffing equipment did you use then? Poly is more difficult to buff because it is tougher than Lacquer. A large Arbor buffer is probably best, but you could make do with smaller types. I use doubled 8" buffing wheels mounted in my drill press and run it at about 800 rpm. The smallest would be the foam pads made for hand drills.
Rocky

Poly burns a lot easier so you gotta keep the RPM and the diameter down! Really down!

The larger the wheel, the faster the outer diameter speed in inches per second and once you pass the point of no return you will end up scraping the clear off and starting all over again.

Keep the speed down and keep the diameter of the wheel you use small - under 10 inches is better - but 8 inches is better yet.

I wouldn't take a 12" over 200 RPM or a 10" over 300 RPM and your 8" should never go over 400 RPM in my book.

I also have a Blue Point pneumatic polisher/grinder and several Mac/Proto and Snap-On electrics.

[Sardine]

Originally Posted by SurferJoe46

Lately I use cornstarch and pure talcum powder and a 10" poly wheel at 300 RPM.

After that a solid carnauba paste wax at 300 RPM on a clean terry head. Repeat every other day for a week and it's done.

Originally Posted by SurferJoe46

Poly burns a lot easier so you gotta keep the RPM and the diameter down! Really down!

What kind of finish are you using? Most modern conversion finishes (read: 2-component, requiring a catalyst, with the exception of UV urethane) are far more heat and abrasion resistant that nitrocellulose.

Also, cornstarch, talcum powder and carnauba wax? What magic is this? I very much doubt that foot powder has the desired abrasive properties to buff a finish, much less the regularity in particle size required for an even scratch pattern. And although carnauba wax is great stuff in its place, I don't see any reason to apply it on top of a film coating far more durable than the wax itself, and in the event that it were desirable, a single application should be more than adequate. Waxes are too soft to develop appreciable build.

If your methods are based on personal experience and work for you then more power to ya, but if not you may want to re-evaluate your finishing procedures.

As an aside, just to debunk this myth for any unaware, high gloss finished are attained by abrasion, not from the heat produced by buffing. The heat is merely a by-product.

Vinnydbass, I'm guessing you don't have a pedastal buffer, in which case the foam dill buffing pads that stewmac sells are great. (You can also sometimes find these at auto parts stores.) Use paste buffing compound with these, and if you use a liquid swirl remover, apply it by hand with a very soft cloth. If you use a powered buffer for this, you'll paint your shop with swirl remover.

[SurferJoe46]

Well - footpowder is not what I said - you assumed that somehow.

I said 'talcum' and that's an industrial grade polishing trick from many years ago when swirl removers (Black-Magic types) weren't available.

It has such an exceptionally fine tooth that it really just seems to glide over the surface and not cut at all - but it is really creating microscopic conchoidal surface fractures - which the carnauba will fill in later.

I used talc for final polishing to within a 1/2 helium light band for some liquid oxygen centrifugal pumps when I worked in cryogenics. It was amazing to me to see the metal actually become more and more polished as talc was pressure ground over the surface.

Believe me it is one of the finest finishing abrasives you can find. Place a tiny bit between your teeth to see for yourself.

Carnauba - not carnuba - will provide a thixotropic layer that keeps the surface from burning - and yes, there's heat. With cutting/polishing there is always heat.

'Waxes' are too thin to form a good surface - you're right - but CARNAUBA is one of the hardest waxes - in fact it needs severe high pressure milling to even get it to the 1/4 micron particulate size small enough to suspend in a vehicle.

EVERY surface has minute scratches and flaws, and carnauba bean wax is very much capable of filling small valleys and scratches in the final surface.

Carnauba wax also builds well and it has a really good ability to accept more build up after 24-48 hours of solidifying. This ain't Turtle Wax or Simonize.

I've painted for years - yes even some of the modern two part polys and kickers - and as good as they are they can always be improved upon with a good buffing of carnauba.

Anyway - I still say to keep the heat down and the RPM to a minimum with a fairly small diameter wheel of your choice - and use the finest compounds and finish with the talc for an unbelievable surface before you put the carnauba wax on.

I like several coats of carnauba --- many times more than 10.

Those that I paint and treat this way have not generated any complaints and the results have worked well for me for a long time.

Yeah - it's a little olde time-y and labor intensive - and that's why I only paint maybe one or two units a year any more. I'm retired from working for a living and I only do this sidebar work as a labor of love --- and always for free for friends.

I do not permit any waiting lists nor guaranty a finished-by date. I'm done when I am done. I may never do another one again. I dunnow.

[Beauchene Implements]

Subbed... and I hardly ever sub. This is great info, SurferJoe!

[LedBelli Bass]

Originally Posted by SurferJoe46

Well - footpowder is not what I said - you assumed that somehow.

I said 'talcum' and that's an industrial grade polishing trick from many years ago when swirl removers (Black-Magic types) weren't available.

It has such an exceptionally fine tooth that it really just seems to glide over the surface and not cut at all - but it is really creating microscopic conchoidal surface fractures - which the carnauba will fill in later.

I used talc for final polishing to within a 1/2 helium light band for some liquid oxygen centrifugal pumps when I worked in cryogenics. It was amazing to me to see the metal actually become more and more polished as talc was pressure ground over the surface.

Believe me it is one of the finest finishing abrasives you can find. Place a tiny bit between your teeth to see for yourself.

Carnauba - not carnuba - will provide a thixotropic layer that keeps the surface from burning - and yes, there's heat. With cutting/polishing there is always heat.

'Waxes' are too thin to form a good surface - you're right - but CARNAUBA is one of the hardest waxes - in fact it needs severe high pressure milling to even get it to the 1/4 micron particulate size small enough to suspend in a vehicle.

EVERY surface has minute scratches and flaws, and carnauba bean wax is very much capable of filling small valleys and scratches in the final surface.

Carnauba wax also builds well and it has a really good ability to accept more build up after 24-48 hours of solidifying. This ain't Turtle Wax or Simonize.

I've painted for years - yes even some of the modern two part polys and kickers - and as good as they are they can always be improved upon with a good buffing of carnauba.

Anyway - I still say to keep the heat down and the RPM to a minimum with a fairly small diameter wheel of your choice - and use the finest compounds and finish with the talc for an unbelievable surface before you put the carnauba wax on.

I like several coats of carnauba --- many times more than 10.

Those that I paint and treat this way have not generated any complaints and the results have worked well for me for a long time.

Yeah - it's a little olde time-y and labor intensive - and that's why I only paint maybe one or two units a year any more. I'm retired from working for a living and I only do this sidebar work as a labor of love --- and always for free for friends.

I do not permit any waiting lists nor guaranty a finished-by date. I'm done when I am done. I may never do another one again. I dunnow.

So there!

[Sardine]

Originally Posted by SurferJoe46

Well - footpowder is not what I said - you assumed that somehow.

I said 'talcum' and that's an industrial grade polishing trick from many years ago when swirl removers (Black-Magic types) weren't available.

It has such an exceptionally fine tooth that it really just seems to glide over the surface and not cut at all - but it is really creating microscopic conchoidal surface fractures - which the carnauba will fill in later.

I used talc for final polishing to within a 1/2 helium light band for some liquid oxygen centrifugal pumps when I worked in cryogenics. It was amazing to me to see the metal actually become more and more polished as talc was pressure ground over the surface.

Believe me it is one of the finest finishing abrasives you can find. Place a tiny bit between your teeth to see for yourself.

Carnauba - not carnuba - will provide a thixotropic layer that keeps the surface from burning - and yes, there's heat. With cutting/polishing there is always heat.

'Waxes' are too thin to form a good surface - you're right - but CARNAUBA is one of the hardest waxes - in fact it needs severe high pressure milling to even get it to the 1/4 micron particulate size small enough to suspend in a vehicle.

EVERY surface has minute scratches and flaws, and carnauba bean wax is very much capable of filling small valleys and scratches in the final surface.

Carnauba wax also builds well and it has a really good ability to accept more build up after 24-48 hours of solidifying. This ain't Turtle Wax or Simonize.

I've painted for years - yes even some of the modern two part polys and kickers - and as good as they are they can always be improved upon with a good buffing of carnauba.

Anyway - I still say to keep the heat down and the RPM to a minimum with a fairly small diameter wheel of your choice - and use the finest compounds and finish with the talc for an unbelievable surface before you put the carnauba wax on.

I like several coats of carnauba --- many times more than 10.

Those that I paint and treat this way have not generated any complaints and the results have worked well for me for a long time.

Yeah - it's a little olde time-y and labor intensive - and that's why I only paint maybe one or two units a year any more. I'm retired from working for a living and I only do this sidebar work as a labor of love --- and always for free for friends.

I do not permit any waiting lists nor guaranty a finished-by date. I'm done when I am done. I may never do another one again. I dunnow.

More power to ya then. When you mentioned cornstarch and talcum powder in the same sentence, I naturally assumed (erroneously, it would appear) that you were referring to the types sold in grocery stores for skin care.

As far as carnauba wax, I know what it is; I use it all the time as a friction polish on woodturnings. But even as hard as it is, it has always shown damage and smudging after a lot of handling. While it does leave a gorgeous finish, I personally wouldn't use it on something that is by nature handled as heavily as an instrument, especially not on a fretless fingerboard.

[SurferJoe46]

Have you ever buffed out a finish with PBA*?

I've got 40-lbs of the dry powder yet from Plastics Lab, and used it a lot then but not since.

*Poly-Butylactate or mold-release agent, and it's extremely hardy and won't wear off easilly. The sheen and luster looks like liquid glass after a buff out.

[vinnydbass]

to anyone who wanted a follow up for my project:

DIY Fretless!!!