Spraying Poly?

[koshersteel]

howdy,

  Well, I'm done finishing w/ Nitro, the stuff just makes me sick. I'd like to switch to a poly but don't know much about it. Are there any major differences between spraying poly vs. nitro or is it basically the same idea (building an architecture of thin layers and then polishing to a mirror finish) with a different product? Would I mix colors into poly (what kind of dyes) or just spray the dyes mixed w/ alcohol and trap the color between layers?

  I was thinking about using System 3 WR-LPU topcoat since I am already using the System Three clear coat for pore filling. Is there an industry standard brand when it comes to poly (like McFaddens w/ Nitro)? What does Warmoth use?

  Thanks for any help you guys can provide? Cheers,

 

[Patrick from Davis]

I used General Finishes gloss poly urethane on my bass body a while back.  This was with an HVLP gun and turbine system a friend has.  The weather was important.  Too hot and the stuff would dry before it hit the body and turn gritty.  It was very easy to do, just the gun cost a mint.  There were these Scotch Brite like pads that were 600 grit my friend had, and you have to "dull up" the previous coat for the next to stick well.  You do not have to do this every coat, but it is just another level of insurance so I did it every time.  The thinner the coats the better, and I had sprayed about 7 coats quite thin on it.  It looks like it just goes from spotty to continuous, and stop.  The levelers in it would work and it'd look like a million bucks in 30 minutes.

Polishing, 400 wet seemed to bite a lot.  Kinda scary, you wet sand with friggin 400 and it seems like it is just blazing through the finish.  Then I went to 600 wet and then 1500 wet sanding.  Polished it with Turtle wax car polish.  I just used clear, so I am unsure about adding the dyes.
Patrick

 

[-CB-]

You might want to look into SprayMax 2k clearcoat as a top coat.  Its a true 2part in 1can topcoat. 

You will need to scuff sand with 400 or 600 between coats.

Poly - as in Home Depot type - polyurethane finishes are not suitable, far far too soft.

The 2k epoxy is hard as nails like car paint.  Hell, it IS car paint.

These finishes do not blend and melt into each other, so you do need a scuff sanding, cleaning, dust removal between each coat.  Three medium thick layers of epoxy should be just fine - my test shows that two coats is perhaps not quite there on wood samples, but worked ok on a metal piece - such as a motorcycle fender.  Level sand and buff the final coat.

If nitro makes you sick, then an epoxy finish will make you sicker - for EITHER finish - go get a 3m organic vapor mask and use the damn thing ALL THE TIME.  Nitro will wipe your brain out faster than bourbon on steroids, the effect being cumulative. Epoxy (poly) that dries hard (as opposed to the crap they sell as consumer products) will tear your lungs out, resulting in chemical asthma that is permanent and damn near untreatable.  Use the mask!!!!!  If you can smell the fumes - the mask is shot, get new inserts for it.

 

[SimsCustomShop]

Polyester is what I use (for a sealer anyways) its hard as a rock

 

[MedianMusic1]

Warmoth uses polyester as a base coat to fill the wood grain, then Urethane as their primary finishing material. For my phoenix guitar project I used Alsa Killer Cans (automotive urethane) throughout. It's great stuff, but expensive. For my challenger guitar project I used Duplicolor filler/primer and their Truck, Van, & SUV colors (automotive acrylic lacquer). For finishing, I used Spray Max 2K Urethane clear with no compatibility issues. Check out my video below...

[youtube=425,350]http://www.youtube.com/watch?v=qwws6f0r2iw[/youtube]