Best adhesive for gluing perspex?

[hootsmon]

Sorry if this has been answered previously, but can anyone recommend a good adhesive for gluing perspex?

Basically I've found some offcuts of perspex-sheet (say 5mm-10mm thick).
I'm toying with the idea of laminating 2-3 sheets together, in order to make a taillight diffuser, or possibly some sidelights as well. Ideally, I'd like the joint to be optically clear, as well as mechanically sound. However I've read that araldite (epoxy) does not give a clear join on perspex.

Any ideas? What about...

• SuperGlue (ie, cyanoacrylate) or
• Tarzan's Grip (a solvent-based glue)?

 

[trout]

superglue is out as it fogs the perspex .

there was a groupbuy in the marketplace for optical epoxy

 

[Steve K]

I make some housings from perspex (a.k.a. plexiglass here in the states). The walls usually get epoxied together, and then I tack the top on with RTV. The epoxy is the basic two-part type, and does get yellow with age. The RTV stays pretty clear, and would be a good choice for bonding one layer to another.

Is this the best way to diffuse light, though? Would you do better by using an abrasive to roughen the interior surface of the perspex?

I've been having similar thoughts, as I want to build a backlight for a stained glass window.

Steve K.

 

[hootsmon]

I make some housings from perspex (a.k.a. plexiglass here in the states). The walls usually get epoxied together, and then I tack the top on with RTV. The epoxy is the basic two-part type, and does get yellow with age. The RTV stays pretty clear, and would be a good choice for bonding one layer to another.

Is this the best way to diffuse light, though? Would you do better by using an abrasive to roughen the interior surface of the perspex?

I've been having similar thoughts, as I want to build a backlight for a stained glass window.

Steve K.

Thanks folks, you've given me plenty of info to give this idea a shot.

Regarding the taillight diffuser, my description wasn't all that clear (sorry). What I'm planning is just a 'Dinotte-style' helmet-light, that could accept a cylindrical perspex 'diffuser' optic, forming an end-plug at the back of the aluminium tube. So the diffuser would just be of a couple of perspex discs laminated together, and shaped so it's a push-fit into the 28mm ID tubing. Then I'd fit 1 or 2 red LEDs (using epoxy?) onto the inside surface of the perspex, with the intention of lighting-up the whole end-plug with red light. And yes, I was thinking of cutting the discs with a holesaw, so there'd be lots of machining marks to 'frost' the surface anyway.

 

[znomit]

I get stuff built out of perspex at work.
The engineer uses this concoction:
Perspex 5gms
Glacial Acetic acid 10ml
1,2 Dichlororethane 100ml
Well polished surfaces gives a very tidy join(some parts you cant tell its two pieces).

Some acrylics get nice and bendy in hot water and you might be able to fashion a curved dome that would work well too.

 

[hootsmon]

Ah, thanks Znomit. After inspecting some some perspex aquariums (I mean aquaria), I sort of guessed that some sort of solvent-based adhesive like that would give the best results. Not sure I can justify chasing those ingredients, however I'll probably try experimenting with a few easier-to-obtain solvent adhesives first.

 

[trout]

Ah, thanks Znomit. After inspecting some some perspex aquariums (I mean aquaria), I of guessed that some sort of solvent-based adhesive like that would give the best results. Not sure I can justify chasing those ingredients, however I'll probably try experimenting with a few easier-to-obtain solvent adhesives first.

We have a plumbing solvent based adhesive which is clear and used for plastic pipes You must have similar .

 

[hootsmon]

Good thinking; in my shed there should be some PVC solvent-adhesive. The PVC adhesive we get here is usually a bright blue colour, but it's still promising, and worth a try to see how well it bonds perspex. Assuming that works then I'd try plumbing-supply shops for a clear version.

Edit -- Yep, just checked and PVC adhesive is readily available in clear form as well.

 

[hootsmon]

Just an update... Still haven't tried PVC adhesive, because while browsing my local hardware shop, I decided to try Selley's Plastic Glue instead. It's not all that cheap, but it seems to meet the requirements OK. As a test I laminated 2 perspex cubes together. The glued joint is mechanically strong and optically clear; actually I suspect it might have been even clearer if I'd spread the glue more evenly. Here's a pic. (oh and pls excuse the saw-kerf ;-)).

 

[dinosaur]

glue with methylene chloride ~ a solvent, works by seeping between assembled joint and melting the acrylic ~ polish with duraglit wadding.

there are silicon adhesives specifically designed for strong glass to glass jobs ~ if you require something that needs a filler/adhesive combination search for 'aquarium silicone sealant'.

nb:

• the bathroom/kitchen silicon sealants have fairly low adhesive properties.
• pva does not survive if damp ~ especially warm damp.
• even if your item remains dry pva adhesives will not truly bond non-porous materials ~ the joint will behave as ultra brittle, more so with time.