Reverse laser engraving, painting and laser cutting

[David DiPietro]

I am trying to quote on a job where I need to reverse engrave 450 4" x 2" (gemini clear matte/gold) and spray paint when engraved. The question I have is:
should I set up a matrix and engrave them all at the same time without vectoring out the actual size. Paint the entire sheet and then return to the laser and cut them out or do one at a time.
Another question is: is there a special paint I should be using? I tried this with Krylon for plastic and it seemed to be fine except for the smoking when I cut it out.
Lastly, I will need to apply adhesive tape so they can be mounted. I don't know if the adhesive will react to the paint?
Any input or suggestions would be greatly appreciated and what would be a cost to do the job, I am figuring $6.00 to $9.00 per plate.
I would be using a ULS 45w laser.
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Forgive me if the pic didn't load properly.
Thanks for having a look -

[Mike Null]

It is my practice to paint after engraving. I engrave and cut at the same time. You can speed your cut time by using the table tool in CorelDraw and convert it to curves. that will allow you to cut the full length and width of the engraving sheet in single passes rather than cutting each plate seperately.

Krylon has always worked well for me.

My pricing would be about $5.50 for those.

[David DiPietro]

It is my practice to paint after engraving. I engrave and cut at the same time. You can speed your cut time by using the table tool in CorelDraw and convert it to curves. that will allow you to cut the full length and width of the engraving sheet in single passes rather than cutting each plate seperately.

Krylon has always worked well for me.

My pricing would be about $5.50 for those.

Thanks Mike!
I will be using the matrix setup in Gravostyle which is pretty handy. Q; why would you paint after cutting? It just seems easier and cleaner to paint the entire sheet and then cut them out.
I am assuming you choose that method because of the off gas?

[Mike Null]

I felt that I could be more precise in my cuts.

[Kev Williams]

Nice thing about reverse engraving that will be taped afterward, don't need to worry about 'staying in the lines' ;)

My wife does most painting, the way she'd do it use flat black canned acrylic paint, brush it in and squeegee it off with transfer tape squeegee (we use the 'gold' squeegee's that never seem to wear out). The squeegee fills the engraving good, and cleans off enough of the excess in one or two swipes that you can just tape over it. Leftover paint on the squeegee gets smeared on the next part or swiped across the yellow pages. You can do this in full-sheet form or 1 plate at a time, doesn't really matter. Flat black acrylic dries fast, Windex or DNA cleans up after.

What I don't like about spray painting is no matter how much or little there's masking to do, which means UN masking to do, and hardly ever is one coat enough- the exception being black appliance epoxy, love the stuff but wear long sleeves and do it outdoors, protect your glasses, etc, the overspray goes everywhere and is sticky as -- epoxy! :D -

all the above is why we rarely spray, in the long run we get better results with less work swiping paint in/on...

[Mike Null]

Kev
i don't mask on this kind of job. I just spray the entire back side.

[Hilton Lister]

Just on the subject of engraving reverse plastic. Is there any foolproof way of getting a clean engraving so that the colors are sharp and clear? I always used to do 2 passes, one on focus and one out, but lately, I still have been unable to clear the dusty or cloudy finish. I'm not sure whether it is due a difference in materials or something I'm not doing correctly. How much out of focus do others use?

[Kev Williams]

... but lately, I still have been unable to clear the dusty or cloudy finish...
For that very reason I don't laser engrave in reverse, tool engraving only. Except for one customer, because I'm matching existing signage from their previous vendor, matte gray and matte maroon with white lettering using IPI material. When lasered, white paint barely gets to a light gray, which matches the old signs. Looks good, just not white. Tool engraved, white paint comes out WHITE :)

[Mike Null]

I believe all the reverse engraving I have done is using cast acrylic. Laser engraving cast will leave a frosted finish. When I'm doing this most of my paint color selections have been white or black which give a good color.

On the Rawlings signs they were filled with white paint. The restaurant sign was sprayed with red, engraved then brush filled with the other colors.

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[GLENN BRADDY]

To get rid of the frosting.. I have used
Meguiar's® PlastX™ Clear Plastic Cleaner & Polish, G12310, 10 oz., Liquid. Hope this helps!