OT: Clear Coating Over Oil-Based Paint

[Nerdlinger]

Hi Everyone!

I made a thing out of brass, engraved letters .015" deep, painted it with oil-based paint, then faced the surface the letters are on. It looks awesome since the surface is a nice shiny brass with perfect paint-filled letters. I spray lacquered the whole thing in an attempt to preserve the appearance and the lacquer on top of the paint instantly blistered/wrinkled. Google confirmed you cannot do that but I am having some trouble finding what CAN be done to clear seal over oil-based paint. I will continue to research on-line but thought I would ask if anyone has any first-hand experience on this topic.

Thank you!

 

[surplusjohn]

try a varnish, solvent would be mineral spirits vs lacquer thinner.
oil paint cures by oxidation, once it is cured it is resistant to mineral spirits but not the stronger solvents used in lacquer.

 

[cosmos_275]

shellac or wax might work, but not durable.

 

[Dan from Oakland]

Clear Krylon acrylic in a spray can is pretty mild and should not raise your oil base paint.

 

[michiganbuck]

clear

Rust-Oleum (?)​

 

[Gordon Heaton]

Polyurethane, such as Varathane has worked for me.

 

[Bill D]

Shellac is the classic middle coat or primer coat over unknown s. It sticks on top of anything and anything will stick on top of it.
Bill D

 

[Gordon Heaton]

It's not the sticking, Bill. It's the incompatibility of the topcoat with the paint that causes the paint to 'fuzz', lift or distort.

 

[M. Moore]

Gordon,
What Bill is saying is that the shellac will stick to whatever paint the OP used without blistering. Then you can use any clear coat over top without any trouble. It really is a miracle finish. It is also used to seal in odours, like smoke. I also just learned the other day that it makes a good
adhesive that can be easily undone and completely cleaned off the part without harsh chemicals. So it can be used for light milling jobs, where surface area to height are reasonable.

 

[rons]

Use 2 part paint that really hardens.

 

[rons]

Clear nail polish is something to try and it doesn't cost too much.
In the electronic project days I used clear nail polish on top of rub-on lettering.
I don't regularly keep up on the prices.

 

[Bill D]

Clear nail polish is something to try and it doesn't cost too much.
I don't regularly keep up on the prices.

Dollar store, Useful for marking wires, rulers, etc.
Bill D

 

[SeymourDumore]

If you have a place near you that is in the business of selling automotive paints, they will have the stuff you need.
I only refer to it as "adhesion promoter" because that is what I was told way back when to call it, but everyone will know what you mean.
It does comes in a spray can, and I swear you can lay it on dogshit, wait 30 minutes, and then you can paint said dogshit any color you want with anything you've got!

 

[boslab]

I did a few months at a sign firm as a youth, incredibly enjoyable btw, they had an engraving shop, they did bank and doctors plaques, the letters were filled with cellulose car paint ( warning if you have an old tin of British racing green on the shelf covered in dust, be careful opening it, I opened one and it exploded, the whole thing was like mr bean painting a room)
The filling was done with a disposable syringe, left to dry and overpainted with clear coat 2 pack .
It was a long time ago btw, I loved engraving, it was so relaxing, I even bought a Taylor Hobson engraver but it was a vanity really, it doesn't get much use .
Mark

 

[Nerdlinger]

If you have a place near you that is in the business of selling automotive paints, they will have the stuff you need.
I only refer to it as "adhesion promoter" because that is what I was told way back when to call it, but everyone will know what you mean.
It does comes in a spray can, and I swear you can lay it on dogshit, wait 30 minutes, and then you can paint said dogshit any color you want with anything you've got!

So the idea is to use the "adhesion promoter" over the oil paint to allow clear coating with anything? My neighbor is a body shop so I'll ask him. Thanks!

 

[Nerdlinger]

I did a few months at a sign firm as a youth, incredibly enjoyable btw, they had an engraving shop, they did bank and doctors plaques, the letters were filled with cellulose car paint ( warning if you have an old tin of British racing green on the shelf covered in dust, be careful opening it, I opened one and it exploded, the whole thing was like mr bean painting a room)
The filling was done with a disposable syringe, left to dry and overpainted with clear coat 2 pack .
It was a long time ago btw, I loved engraving, it was so relaxing, I even bought a Taylor Hobson engraver but it was a vanity really, it doesn't get much use .
Mark

I dig what you're saying...very satisfying to see the "perfect" engraving come out. In the corner of our "pushback room" we have a WW2-era "GREEN" engraving machine. It uses stencils that you trace with a "pen" and an articulating arm that translates the motion of the "pen" down to some multiple (say 5:1) to an engraving bit in a tiny spindle. Totally good for nothing these days but I love that old stuff.

By the way - the term, "pushback room" is part of our every day culture around here. Is that a Precision Instruments original or is that term used elsewhere? "Where do you want this broken blah? Eh, we might need it some day...put it in the pushback room."

 

[Gordon Heaton]

Gordon,
What Bill is saying is that the shellac will stick to whatever paint the OP used without blistering. . .

Just checked on shellac... In my youth, the shellac used for wood finishes was the original type, harvested from some kind of bug. The stuff in the hardware store these days is a man-made chemical compound. Can I count on it to be non-reactive with enamel paint?

 

[rons]

Just checked on shellac... In my youth, the shellac used for wood finishes was the original type, harvested from some kind of bug. The stuff in the hardware store these days is a man-made chemical compound. Can I count on it to be non-reactive with enamel paint?

Called the lac bug that likes trees. India, China.

What Is Shellac? Uses in the Beauty Industry and Environmental Concerns

Shellac is a natural resin used in beauty products from moisturizer to mascara. Learn where it comes from and whether or not it's environmentally friendly.

www.treehugger.com

 

[MrStretch]

Probably not the shellac itself, but what it's dissolved in. Traditionally alcohol is used.

 

[Nerdlinger]

Went with a spray-on varnish. It isn't perfectly leveled...looks like either tiny air bubbles or some dirt/dust got highlighted. Either way the paint is protected and I am still very happy with the project overall. Thank you for all your help!