Acylic Mirror Project

[Jack Harper]

Hello all. I am donating 400 black acrylic mirror cutouts with paint filled etched text and had a few questions.

One: Can I use the plastic film that came on the front of the acrylic mirror sheet as my mask to raster and then paint before vector cutting? Or, should I remove it and apply a new laser mask?

Two: Should I remove the mask befor vector cutting?

Three: I was planning on using the silver Krylon Premium Metallic paint to fill my text etchings. Is there any concern for crazing here?

Thanks.

[Dan Hintz]

If the text is small, I would replace it with vinyl transfer tape... you don't want to try picking out the middle of small letters. With the tape, you can soak them in water for a few seconds and it will rub off. If it's big text, I might be inclined to leave the original mask on as it will have a firmer grip (less wicking).

[Joe Pelonio]

I use tweezers to weed out the leftover transfer tape, it goes very fast if you use a light tac.

The factory plastic film melts to the cuts and also muddies up the etching so is really hard to remove. Paint also sticks to it more than to transfer tape, when you peel it the paint may come off the letters.

[Dee Gallo]

I use a plastic razor blade to remove tiny pieces of transfer tape - fast and easy, won't scratch plastic. They use them for auto detailing, so you know it won't harm the finish.

cheers, dee

[Jack Harper]

Thanks for everyone's input. Anyone have a problem with the Krylon and crazing?

[Rodne Gold]

I wouldnt front engrave them , reverse engraving requires no mask and looks better
PS most plastic used to protect acrylic is PVC based , cutting pex with it on is no big deal , rastering thru it is gonna give off chlorine and that combines with moisture to make HCL (hydrochloric acid) in the machine which is not a good thing.

You WILL have a problem with solvent based paints as most acrylic mirror is extruded acrylic and is highly stressed by the lasering , its a short chain polymer and most solvents will promote stress cracking , you need to use paints that are water based

[Jack Harper]

I wouldnt front engrave them , reverse engraving requires no mask and looks better
PS most plastic used to protect acrylic is PVC based , cutting pex with it on is no big deal , rastering thru it is gonna give off chlorine and that combines with moisture to make HCL (hydrochloric acid) in the machine which is not a good thing.

You WILL have a problem with solvent based paints as most acrylic mirror is extruded acrylic and is highly stressed by the lasering , its a short chain polymer and most solvents will promote stress cracking , you need to use paints that are water based

Rodne- Thanks for the info. I agree with the reverse engraving and did try that. The problem here is, because it is a smoked/black acrylic mirror, it barely shows through the front.

[Jack Harper]

OK. Based on Rodnes' paint comment, does anyone have a recommendation for a silver, water based spray paint? Thanks.

[Dan Hintz]

I don't know how large the piece is, but have you considered gilder's paste for this one? I don't have a specific paint to recommend...

[Jack Harper]

I don't know how large the piece is, but have you considered gilder's paste for this one? I don't have a specific paint to recommend...

Dan - That is how I have been doing my samples and it may be how I end up doing it all. The piece will be about 4' x 5' cut up into 400 pieces.

[Dan Hintz]

Can you thin the paste a bit and use a squeegee on the entire sheet? If you can, that would make the color fill step take 5-10 minutes for the entire lot. If you need to mask a portion off, maybe consider a mask similar to what PCB guys use for screening on solder paste... not nearly as fast as doing the entire sheet at once, but would still allow you to quickly squeegee the paste on without getting it into other areas.

[George Brown]

PCB guys use for screening on solder paste...

What do they use??

[Dan Hintz]

For large runs, they use several-mil thick piece of SS, but for small runs a piece of styrene or PETG