Engraving multiple paint layers

[Craig McWilliam]

I've been figuring out cutting and engraving on a Speedy 100R virtually on my own, with varying results, and lately I've had to engrave a top layer of coloured paint off of a white base coat on both plastic and aluminium. On flat panels we've applied silk screening paint as evenly as possible with a spray gun and although the results have been good the paint is never completely even and touching up areas without going through the bottom layer is tricky, engraving on parts that aren't flat is trickier.
I've had to engrave the client's 2K Flowline, which is hardier but came with it's own set of problems and their QD enamel which was hugely frustrating.

I assume "laser proof" paint is a bit of a stretch but is there, by some miracle, a type of paint that I can use on both plastic and aluminum as a base coat that will be hardier and more resilient to lasering so I can engrave the top layer off confidently, without having to try tickling a few microns away with each pass?

[Mike Null]

Craig

Welcome to SMC.

I'm not aware of such a paint but we have a lot of members so I'm sure others will have some suggestions.

[Craig McWilliam]

Thank you Mike,
I've been lurking for a while and reading some of the posts by the guru's on here made me feel a bit like I was bashing buttons on the laser like a monkey looking for a banana. Wish I'd known about SMC months ago.

[Mike Null]

I doubt there are many things we haven't discussed here at one time or another so I'd suggest making the search button your friend. Sometimes that can save days of time over beginning a new thread.

[Dee Gallo]

Welcome to the Creek, Craig! Mike is right, there are threads here on pretty much every subject - start reading from the the beginning and you will learn everything there is to know!

I had some success with automotive primers and layering regular spray paint over it. The primer seems to resist the laser. In this test sample, you can see the 1st 3rd has no primer, the middle 3rd has white primer and the 3rd third has red primer. Over that is blue or black paint. When hit with the laser, the paint comes off and the primer remains. There was a little black primer at the very top, just to confuse you... black on black, was not going to work really... a little too subtle.

In the second example, I used black primer first and covered it with hammered copper paint. By hitting it lightly, I got a brown tone without going all the way through to the black. If you experiment with colors and settings, you can get a myriad of effects.

This technique works well on wood also. Just make sure you have a good couple of primer coats, sanded smooth and lighter cover coat.

[David Somers]

Great idea Dee! This went into into my stash of cool tricks right away! Wonder what it is in Automotive Primer that makes it resistant? Metal particles? Other additives? Hmmmm.

Thanks for sharing this!

Dave

[Joe Hillmann]

I was once brought in a job that was painted with a metal fleck automotive paint and a clear coat. I was only able to engrave into the clear coat and couldn't engrave the paint.

[Craig McWilliam]

Thanks Dee,
I actually read your post on engraving the cake pans a while back, they turned out really well! I'm doing something pretty similar now but not all the pieces I'm doing are flat which makes it really tricky to just get the top layer off. That's why I was wondering if anyone knew of a type of paint that would hold up a bit better against the laser so I could crank up the power to ensure that even the areas that are not perfectly in focus would also get engraved down to the base coat without completely removing it in the areas that are focused.
So far the automotive paint seems to work best but it takes days to dry and layering different colours often ends up with an orange peel finish.

[Dan Hintz]

I was going to suggest as Dee did, a more robust automotive paint as a background, and a lighter/thinner coat of something cheaper as an upper coat (I've made a few projects using that method over the years with great success, but not enough to say it's a guaranteed winner of a method... I may have just been lucky several times).

If your substrate supports it, powder coat would make a great base layer... it can be made much thicker than a typical paint layer, so it will take more abuse before cutting through.

[Dee Gallo]

David,

There was speculation when I first discovered this that the automotive primers use something like titanium, chalk or other powdered stone in their mixture. I don't know, but it was a happy find for me. I do put a couple of coats on to make it thick so that might make all the difference too.

Craig - several very light coats are better than one thick coat. It dries super fast and there is no orange peel. Put each coat on from a different angle too.