PDA

View Full Version : mirror acrylic



Graham Taylor
04-18-2017, 2:15 PM
Hi,

Is it best practice to cut mirror acrylic with the mirror side down or up?

I have a load to cut tomorrow as a rush job and I havent used it before?

As usual, thanks for any help and advice.

Graham

Scott Shepherd
04-18-2017, 2:20 PM
Mirror facing down.

Lee DeRaud
04-18-2017, 2:54 PM
Mirror facing down....with masking/transfer tape on the downward-facing side, just like normal clear acrylic.

That said, with the transfer tape on the 'money' side, I've cut it both ways, doesn't seem to make a difference.

Joe Pelonio
04-18-2017, 11:19 PM
I agree, either way works if you put transfer tape on it, but if you try to cut mirror side up bare, you may etch the inside of your cover. I know this from experience.

Pieter Swart
04-19-2017, 6:49 AM
I you cut the mirror side up, you may end up with a double image from the reflection, if you need a crisp image then mirror side facing down would be best.

Bert Kemp
04-19-2017, 11:32 AM
Question........ do you laser off the backing like you would a regular mirror?

Graham Taylor
04-19-2017, 12:42 PM
1st lot done, man does this stuff stink :eek: - much more than the normal acrylic so I assume it is the backing material.

Joe Pelonio
04-19-2017, 11:34 PM
Question........ do you laser off the backing like you would a regular mirror?
I have, yes, engrave off clip art, then apply translucent vinyl, and hang in a window. Nice effect when the sun hits it.

Dennis Watson
01-27-2018, 4:33 PM
Im burning thru. Mirror side up or mirror side down, what?

Trying some mirrored acrylic for the first time this morning and seems I am getting best results from leaving the plastic protection on with grey side on bottom. If I put the grey side on top I get a reflection arc.

This is opposite of what is said here, right?

Weird that if I cut with no plastic or painters tape on top it fogs inside.

Lee DeRaud
01-27-2018, 5:13 PM
Trying some mirrored acrylic for the first time this morning and seems I am getting best results from leaving the plastic protection on with grey side on bottom. If I put the grey side on top I get a reflection arc.If you're vector-cutting it, just treat it like regular clear acrylic. You need to mask the bottom side or you get marks from beam bounce-back off whatever table/grid/pin-array it's sitting on. The fogging you speak of is the same bounce-back effect, but from the reflective side of the mirror coating.

I take the plastic stuff off: I just don't trust it to come off cleanly after it's been melted/burned during cutting. I then remask one side with transfer tape...that's the side that goes down. For the mirror stuff, that's the uncoated side, since I'm usually rastering the coating off, but that's also the right way for vector-cuts.

Summary: peel, mask clear side with transfer tape (or painter's tape for small pieces), cut/engrave clear side down, coated side up.

(At this point someone will come along asking about front-surface mirrors, but if front-surface mirrored acrylic exists, I've never seen it and wouldn't have any use for it anyway.)

Dennis Watson
01-27-2018, 6:11 PM
Lee,

Im in for the night now so tomorrow I will try taping the clear side with the painters tape and then turn it over and burn thru with the grey side up. I am cutting out letters for a friends Cobra mustang that he will put on his trunk lid cover. So the letters are roughly 3" x 7" long.

Nice and big and no rastering.

Kev Williams
01-28-2018, 1:11 AM
To say 'mirror side up' is confusing; if the shiny side is facing up, the coated side is actually "down"...
--same thing with 'mirror side down', the mirror itself isn't up, but the coating is...
;)

My take- no matter what plastic you're cutting, if you want a pristine cut then transfer tape both sides. For mirrored plex, put the COATED side up so the laser hits it first-- as the laser cuts thru the non-reflective side it vaporizes the reflective side, and transfer tape won't reflect back laser light. The only reflections will be of the white visible light caused by the heat of the cutting.

Mike Null
01-28-2018, 8:22 AM
I cut some red mirrored acrylic last week, face down, and a black outline followed the cut line. Not too noticeable but if you were looking, it was apparent. I pointed it out to the customer and they didn't mind.

Dennis Watson
01-28-2018, 12:21 PM
Yesterday evening I was burning 3/8" holes as a test and I did get good results with the grey side on bottom, painters tape on top and running the feed rate high and burning each hole 4 times to cut thru.

Oh and i am raising this acrylic 1/8" above the table with some scrap pieces of birch so there is no possibility of flashing back.

John Lifer
01-28-2018, 7:32 PM
I engraved a 24x24" the other day, Rowmark Mirror, Into the Mirror material, which is the back reversed. Worked perfectly, I ALWAYS remove the plastic or paper depending on the acrylic. My customer gave me some acrylic mirror, and I test engraved his logo, again on the back in reverse. No issue at all. If you are trying to engrave on the front, Yes, I might leave layer on..