Help dealing with the semi transparency of acrylic?

Hey guys!! So I’ve been getting really into the acrylic side of things and have been absolutely loving it. I have run into an issue with the semi-opaque quality of the acrylic on a couple different occasions. I was wondering if anyone had any solutions to this.

Basically what I’m running into is just when I do an installation or assembly I end up with either seeing either the transfer film or the glue through the white acrylic. Obviously the ideal solution would be getting thicker acrylic but right now glowforge isn’t offering quarter inch acrylic in the larger sheets which is what I tend to use and order.

You should be able to see behind the white acrylic where my glue stops. I would love to put glue all the way to the edge but then it overflows and ruins the backboard.
20190702_124500|500x500

For anyone curious this is the final project.

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I can’t see what you’re referring to in the picture, but when you say glue, are you using acrylic cement?
https://www.tapplastics.com/product/repair_products/plastic_adhesives/tap_acrylic_cement/130/296 or equivalent?

You apply that to the edge after the two pieces are put together and it wicks into the seam eliminating the sort of edge I think you’re referring to. I’m terrible with glue and even then I only sometimes get tiny bubbles. For something as precise as your sign I’d cut out a matching piece of masking tape to cover the black, glue the white on, and then pull the masking

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Yeah, it’s hard to see in the photos but there is a darker sort of shape on the bottom half of the skyline where you can see where the glue went up to but not Beyond. And yeah that is the glue I’m using. I can’t get too close to the black without fear of it ruining the background. I like the idea of the Mask. I have a feeling that wouldn’t work in this case.

Also try scoring the acrylic around the outline. That will create a sort of “fire break” for the solvent/glue so it doesn’t overrun.

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You can probably find a more opaque acrylic. Some of the major distributors sell varying opacity plastics.

Or you can use an opaque background sheet…that should cut the light transmission through the white.

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Both good suggestions!! I’m a sucker for the proofgrade these days. I haven’t broken into other suppliers but yeah that’s probably where I need to do. Darn.

PS
Glowforge, if you’re reading this, I will send you a pizza if you start selling quarter inch large sheets of acrylic.

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If you’re going to branch out from PG, acrylic is the place to do it. I’ve had no issue with any of the non-PG acrylics I’ve tried, other than mirrored, which was a PITA. And I typically just use PG settings where possible.

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Glowforge isn’t manufacturing their own acrylic. You will easily be able to find what you need at another supplier.

For the pieces you have shown you would find good success with 3M 9502 tape. It is a double-sided tape that you apply to the underside of the pieces you are cutting. It gets cut through with the acrylic, then you peel off the masking and stick it down. It is not optically clear but in this application whatever kind of shadow it might cast would be even across the entire piece. I bet it would look good.

You can see some more adhesive notes of mine here.

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I could swear I’ve bought 1/4" thick PG acrylic before…

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Nice project and very cool you’ve been diving into acrylic! I adore the stuff. Luckily acrylic is pretty much acrylic since the chemical composition of it doesn’t vary much so it might be worth seeking out a local supplier for the quarter inch stuff. I don’t buy acrylic online anymore since I can get it so much cheaper locally. (I could make a killing selling the green edged stuff that’s always out of stock here. I have stacks of it laying around from my local store. :stuck_out_tongue: )

The folks at my Tap plastic said it’s extremely difficult to get a clear gluing becasue it’s hard to keep from getting air pockets and bubbles. I gave up after dozens of tries and figured if the pros couldn’t do it, I never will. So now I design around it and try to hide the seams or I use the 3M tape, but it’s still not perfect. I apply the tape before I cut everything out so it’s a perfect match on the edge. It does get pricey though since there’s some wast of tape and you can still see the air bubbles in it a little bit. For smaller pieces the acrylic solvent works best, but if it can’t flow to the middle of the piece you’ll still end up with a visible air pocket.

Oh hey, another solution is to use matte acrylic when you can as it hides the glue and fingerprints. I love the texture and feel of it and if I had to choose, I’d say it’s probably my favorite materiel. Not that it helps you here, just FYI.

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I’m sure you have…they do carry 1/4"…in a few of the acrylics.

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@geek2nurse emphasis mine. Have you gotten the big sheets of it? I didn’t think they had ever offered the thick stuff in the Pro sized sheets, but maybe they did and I never noticed because I only have a basic :thinking:

You might try other vendors such as estreetplastics.com that have varying opaquenesses of acrylic. They have a small sample kit with all their whites that you could test out. I’ll post the link below.

Their acrylics cut excellently using proofgrade settings. I generally order 30-50lbs of acrylic at a time from them, mostly black and white but all thicknesses.

https://www.estreetplastics.com/category-s/326.htm

Aside from that, when I need to solvent weld acrylic face to face like that and dont want to risk dribbling solvent on the background, I’ll stand the pieces up on edge, at an incline closer to vertical. This makes it easier to land the solvent on the edge of the top layer. If there’s a large surface area to glue, I’ll make the tiniest gap at the top edge of the pieces to give air bubbles a place to float out.

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Oh, THAT kind of larger. No, I’ve got a basic, so I’ve only bought the 12x20".

I like this idea. Maybe peel and spray paint one side of the acrylic black prior to cutting.

This would make it 100% opaque so you could use any thickness you wanted and save time and money in the process.

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