Rainbow Sheen in the Lacquer

[brewsterallen]

Finishing up a body project and I have been spraying clear lacquer over black lacquer one coat per day. At this point I am letting the lacquer cure before final sanding and buffing. I have noticed, when holding the body on an angle, there is a rainbow sheen to the finish. Will this buff out when I polish the body?

[drmcclainphd]

Originally Posted by brewsterallen

Finishing up a body project and I have been spraying clear lacquer over black lacquer one coat per day. At this point I am letting the lacquer cure before final sanding and buffing. I have noticed, when holding the body on an angle, there is a rainbow sheen to the finish. Will this buff out when I polish the body?

Not likely. You're seeing a diffraction pattern of differing depths of layers, with differences that are close multiples of the wavelengths of light. Like octaves for photons. You see the same from oil film on water and the business side of CDs and DVDs. The layers underneath are bouncing photons between their surfaces, and the ones that come out to whole number multiples of the wavelength make it through. The others bounce around until they decay or find a place where the thickness is a multiple of their length. Since the effect is due to layers already covered over, the more you put on the deeper they're buried. They won't rub out. Maybe sand out. Polishing will just put a smooth surface on the topmost layer.

But before you freak and take a grinder to it, look at it. Is it cool looking? Cool enough to keep? I've had more than a couple 'happy accidents' over the years.

As for lacquering, why clear coat it? A good surface doesn't improve with clear, and a good lacquer stands up to stuff without the extra protection. Clear will scratch white. Black will scratch black. Initially they're both white but you can polish black back to black. Polishing the white from clear gets foggy/translucent white at best.

Best lacquer is appliance epoxy. Super tough, super shiny, super easy to get great results. BUT. Every coat has to go on within 30 minutes, and then it has to sit for at least a week. This is because the epoxy lacquer has so much more volatiles. They seep out slowly through the paint. If you trap them under another layer more than 30 minutes but less that a week later, the surface gets crazed from the outgassing. Glossy alligator skin looking surface is not pretty and epoxy is a downright sunnagun to sand off.

It *can* cover your present surface. Completely and well.

[bullfrogblues]

Sounds like it could be 'blushing' in the lacquer, moisture trapped in the finish.

[brewsterallen]

Originally Posted by bullfrogblues

Sounds like it could be 'blushing' in the lacquer, moisture trapped in the finish.

That's what I was thinking. Purchased a can of Blush out. I will post my results when I have the opportunity to spray when the weather is better.

Thanks for all your posts!

[Keyser Soze]

If it is blushing your best option at this point may be to wait and let it dry further, the problem may self correct. Even if it is not blushing as each layer contracts/gets physically thinner it's ability to noticeably refract will diminish.

[brewsterallen]

Originally Posted by brewsterallen

That's what I was thinking. Purchased a can of Blush out. I will post my results when I have the opportunity to spray when the weather is better.

Thanks for all your posts!

Yup, blush out removed the rainbow effect. It also crazed the final finish. Well, I'll wait until it cures and sand it out with 400. If I hit wood I'll just repaint in black. If i don't blow through the black, I'll just finish what I have.

[drmcclainphd]

Originally Posted by brewsterallen

Yup, blush out removed the rainbow effect. It also crazed the final finish. Well, I'll wait until it cures and sand it out with 400. If I hit wood I'll just repaint in black. If i don't blow through the black, I'll just finish what I have.

Maybe not removed so much as melted it into the base coats. My sympathies.

Seriously, spend the $6 or so for a can of Rustoleum appliance epoxy.
Get a scrap of otherwise inferior wood, even a piece of 2x4, and give it a thin coat on just one surface say, every 5 minutes for 30 minutes. Then let it sit a day and look at it. I knew guys who were paying car painting places $100 to bring their stuff in and have the left overs sprayed on for them. They all said my results were better, and when I told them how they all switched. Sand your stuff down and wait 7 days, and the epoxy will cover even the left over patches. Ain't no truth like physical proof in hand.

[brewsterallen]

Originally Posted by drmcclainphd

Maybe not removed so much as melted it into the base coats. My sympathies.

Seriously, spend the $6 or so for a can of Rustoleum appliance epoxy.
Get a scrap of otherwise inferior wood, even a piece of 2x4, and give it a thin coat on just one surface say, every 5 minutes for 30 minutes. Then let it sit a day and look at it. I knew guys who were paying car painting places $100 to bring their stuff in and have the left overs sprayed on for them. They all said my results were better, and when I told them how they all switched. Sand your stuff down and wait 7 days, and the epoxy will cover even the left over patches. Ain't no truth like physical proof in hand.

OK, but this is epoxy you can't polish it like lacquer right?