What Did You Do Today (2016)

[Neil WyattModerator @neilwyatt]

I think the last several issues have had letters about gluing perspex.

244 – query about bonding acrylic from Ken Willson at the end of a letter

246 – one letter

247 – one letter

248 – two letters

Curiously most of the responses came from the Antipodes.

Most suppliers of cut Perspex/Acrylic offer Tensol in 50g and 500g bottles, it's also on eBay.

The main advantage seems to be that it runs very freely into a close joint by surface tension and the resulting bond is closer to a 'weld' than a glued joint. Superglue is very messy because of the bloom even though the glue is, essentially, acrylic itself.

I have some dichloromethane clutch cleaner so I will collect some in a jar for a quick trial.

[MikeParticipant @mike89748]

I've made vandal-resistant windows out of polycarbonate sheet. At one time the rumour was that it would repel a .22 rifle bullet, so I tested it. It won't, but the impact creates so much heat that the bullet home closes up. I can be full of useless information on occasions…..

[Neil WyattModerator @neilwyatt]

Acrylic may or may not be branded 'Perspex', most sellers also sell polycarbonate which scratches more easily but is less liable to crack, especially in thin sheets.

The DIY sheds seem to be moving away from it, Wickes don't sell it any more and B&Q only do it up to 2mm.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 11/12/2016 10:14:40:

… most sellers also sell polycarbonate which scratches more easily …

.

… Really

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 11/12/2016 10:04:20:

I think the last several issues have had letters about gluing perspex.

244 – query about bonding acrylic from Ken Willson at the end of a letter

246 – one letter

247 – one letter

248 – two letters

.

Thanks, Neil … I evidently haven't been reading all the letters

I've been a little pre-occupied for the last twelve months.

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Digging into it a little more Wisegeek has this write-up. It includes the statement "There are some misconceptions about acrylic, namely that it yellows, turns brittle, and cracks over time. Though this might be true of cheap forms of plastic, it is not so with acrylic." (My bold.)

My DIY Sheet has gone yellow, therefore it is not Perspex. (To be fair the store didn't claim it was.)

But it's a comfort to know that the genuine article is still available, buyer take care. Although Perspex is an Acrylic, not all Acrylic is Perspex.

And worth knowing that if a 'Perspex' project goes wrong, the failure could be down to the plastic rather than the solvent. Cheap acrylic, perspex and polycarbonate are visually hard to tell apart. Are there any easy tests that could be used to identify them?

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 11/12/2016 09:58:56:

I've got it in my bone-head that Perspex has become a generic description in the UK for 'any clear plastic sheet'.

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I'm sure you are right, Dave

The abuse of brand names is rife in this country

Hoover, Loctite, Dickson, and Biro are a few that spring to mind.

No-one seems to care much I'm afraid.

… It appears to be accepted as part of the 'evolution' of our language.

MichaelG.

[mark smith 20Participant @marksmith20]

Ive used dichloromethane for bonding acrylic , never used chloroform for it(does it even work?).

I have a metre long 5" diameter perspex tube that i used in my work for fuming wood using conc. ammonia. I had to bond a cap on one end and used the dichloromethane with acrylic filings. It has held for 2 years now ,although i did have to overlap the joint so that it appears like a weld.

Previous attempts ( using superglue and other specalist acrylic glues) held for between 1 week and a month and it wasnt much fun having the bottom falling out and the ammonia going everywhere..

Edited By mark smith 20 on 11/12/2016 10:50:00

[Michael GilliganParticipant @michaelgilligan61133]

This 'Technical Library' page should be a useful point of reference: **LINK**

http://www.perspex.co.uk/

.

Do please note, however, that the company is Perspex Distribution Ltd. **LINK**

http://www.perspex.co.uk/top-nav/about/

… and they also distribute materials other than 'real good old-fashioned Perspex that's the stuff you assumed it would be'

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mark smith 20 on 11/12/2016 10:46:14:

… for bonding acrylic , never used chloroform for it(does it even work?).

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Yes … see ealier posts

[mark smith 20Participant @marksmith20]

tensol 12 is one of the things i used which failed, funny though as it exactly the same as dissolving powdered acrylic in dichloromethane. I had never heard of using clhoroform and being a chemist i wouldnt have thought it would be as effective as dichloromethane (methylene chloride).

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mark smith 20 on 11/12/2016 11:18:57:

I had never heard of using clhoroform and being a chemist i wouldnt have thought it would be as effective as dichloromethane (methylene chloride).

.

Mark,

I would be very grateful for a brief [and not too technical] explanation of why ^^^

Thanks

MichaelG.

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 11/12/2016 10:25:21:

Posted by Neil Wyatt on 11/12/2016 10:14:40:

… most sellers also sell polycarbonate which scratches more easily …

.

… Really

Virtually every supplkier gives those as the pros and cons of acrylic vs polycarbonate.

"Acrylic is more likely to chip than polycarbonate because it is less impact-resistant. It does not scratch easily, however, and will not yellow over time."

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by mark smith 20 on 11/12/2016 10:46:14:

Ive used dichloromethane for bonding acrylic , never used chloroform for it(does it even work?).

Yes, we used to use chloroform at Philips Research Labs for bonding Perspex. It gives a nice clear joint but won't fill gaps.

Chloroform is easily available on Ebay.

Russell.

P.S. I think the  DIY store clear plastic that yellows might be polystyrene.

Edited By Russell Eberhardt on 11/12/2016 11:42:11

[Neil WyattModerator @neilwyatt]

What hasn't been mentioned is clear styrene sheet. This is cheaper than either acrylic or polycarbonate and is the least shatter proof.

Neil

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Neil Wyatt on 11/12/2016 11:42:05:

What hasn't been mentioned is clear styrene sheet. This is cheaper than either acrylic or polycarbonate and is the least shatter proof.

Neil

HIP or high impact polystyrene isn't too bad. I used to use it as the substrate for printed antennas as its RF properties are good.

Russell;

[Marischal EllisParticipant @marischalellis28661]

I will second, third, etc the use of Chloroform as a glue back in the late 60's early 70's. Don't know where it was bought but much used for assembling showcases without frames…so popular of the time. At that time there was much misunderstand, …well around me at least, that perspex could not be cut, with a saw, could not be bent by heat,etc. It was relatively new perhaps on the open market I believe and of course there weren't the adhesives now generally available and in use around then, Always thought the Chloroform was obtained from under the counter somewhere…..friendly nurse?

Best wishes to all.

[Sam Longley 1Participant @samlongley1]

Posted by Mike on 11/12/2016 09:29:59:

Yes, we used to make "glue" for perspex by putting perspex chips and chloroform in a tightly-corked flask, together with a few small steel ball bearings, and shaking it. I'm still here, but considering the number of dangerous chemicals I fiddled with in my 20s, I often wonder why!

But you probably applied a modicum of common sense, learned how to cope with such things, became a more rounded mature person able to deal with problems on your own & did not go running to the nearest H & S claims lawyer when you burnt your finger tips

[FrankiethepillParticipant @frankiethepill]

As a kid I used to use acetone. Dissolve some perspex scraps in acetone in a bottle- leave it to stew for a while (maybe a day or so) and play around until you get a thickish liquid, a bit like the polystyrene cement we use to use on Airfix kits. Ah Airfix kits, happy days making Spitfires and ME109s and hanging them from the ceiling of my bedroom….

[MikeParticipant @mike89748]

Thanks, Sam! Flattery will get you everywhere. But I do come from a generation which would not sue over an accident which was my own stupid fault.

[mark smith 20Participant @marksmith20]

Posted by Michael Gilligan on 11/12/2016 11:23:29:

Posted by mark smith 20 on 11/12/2016 11:18:57:

I had never heard of using clhoroform and being a chemist i wouldnt have thought it would be as effective as dichloromethane (methylene chloride).

.

Mark,

I would be very grateful for a brief [and not too technical] explanation of why ^^^

Thanks

MichaelG.

Michael , my chemistry is a bit rusty ,having looked around google it appears it has been used often for gluing plastics. So i wont go into it other than id expect dichloromethane to be a more effective solvent for acrylic but with shorter working time and chloroform possibly causing more stress fractures. Which is probably why dichloromethane is more used in commercial products. (though appears to have been removed from consumer based paint stripper like nitromors (which is now crap)

They are both similar solvents only different is the chloroform(trichloromethane) has 3 chlorines attached instead of two. . I have used chloroform for dissolving amber.

Also id like to debunk this myth of tv films ,dramas where someone puts some chloroform on a rag and knocks someone out instantly . Virtually impossible in real life unless the person is a willing guineapig and sits there for quite a while, without struggling.

Edited By mark smith 20 on 11/12/2016 12:24:39

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 11/12/2016 11:39:43:

Posted by Michael Gilligan on 11/12/2016 10:25:21:

Posted by Neil Wyatt on 11/12/2016 10:14:40:

… most sellers also sell polycarbonate which scratches more easily …

.

… Really

Virtually every supplkier gives those as the pros and cons of acrylic vs polycarbonate.

"Acrylic is more likely to chip than polycarbonate because it is less impact-resistant. It does not scratch easily, however, and will not yellow over time."

.

The reason I asked, Neil, is that polycarbonate is [was?] the material of choice for motorcycle visors, and similar. …. Chosen for both its impact resistance and its scratch resistance.

Perhaps there are various grades … I know not.

MichaelG.

.

Edit: … a little self-help >>>

It appears that polycarbonate scratch-resistance is provided by a coating !!

http://www.weetect.com/polycarbonate-coating/

I didn't know that 

Edited By Michael Gilligan on 11/12/2016 12:36:40

[CirclipParticipant @circlip]

Chloroform was the modellers fluid for gluing Acrylic back in the early days due to the unavailability of commercial adhesives to the general public at the time. Although "Araldite" had been widely used commercially it wasn't until the late fifties it became the "glue almost everything" (as cyanoacrylates seem to have become). Same with "Cascamite" for wood at the same time.

"Oroglass" was another commercial name (Might have been Beyer) which the dome of one of the coastal resorts attraction was fabricated from which burned rapidly in the sixties and yes, some acrylics do yellow with age and when fabricating, there is a difference between cast and extruded acrylics. Tensol has always worked for me.

Polycarbonate will stop a bullet, dependant on its thickness.

 

Regards Ian.

Edited By Circlip on 11/12/2016 12:48:51

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mark smith 20 on 11/12/2016 12:22:58:

…. So i wont go into it other than id expect dichloromethane to be a more effective solvent for acrylic but with shorter working time and chloroform possibly causing more stress fractures. Which is probably why dichloromethane is more used in commercial products. (though appears to have been removed from consumer based paint stripper like nitromors (which is now crap)

They are both similar solvents only different is the chloroform(trichloromethane) has 3 chlorines attached instead of two. . I have used chloroform for dissolving amber.

.

Thanks, Mark

That was brief, and certainly not too technical

MichaelG.

.

.

"… expect dichloromethane to be a more effective solvent for acrylic but with shorter working time and chloroform possibly causing more stress fractures"

… That ^^^ demonstates the chemist's intuition that you have and I don't

[Roger HeadParticipant @rogerhead16992]

Mark, I got a (very small) bottle of methylene chloride from our local plastic fabricators when I needed to do some repairs to a box of electronics. It worked fine, and I put the remainder away carefully in my general 'glues' cabinet, but a month later the bottle was bone dry. They had warned me about its volatility, but this was a glass bottle with a tightly-fitting lid and seal!

How do you store this stuff long-term?

Roger

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