Thread: Repair to Acrylic

Hi Mark

I think it might be repairable using a windscreen repair epoxy. Where you can get suitable stuff I don't know.

You say "in which my daughter worked" past tense -- she wasn't terminated as a result of the kid's destructive actions?

Hello Ian,

Thanks for the reply. I'll look into the windscreen repair epoxy. I've got some West system from a stitch-and-glue boat build, but will see if the other has specifically different properties.

No, I'm pleased to say my daughter left on very good terms, with an excellent reference from her manager. This was her casual high school/uni job (same one for over six years). Having finished her honours year, she has now got a 'real' (ie, permanent full time) position, using the skills she gained at Uni, in an engineering firm. The kid's mum paid (cost price) for the fish tank, and it was then offered to any employee who wanted (or had a parent who wanted!) to have a go at repair.

I must confess that the tank has been sitting on my workshop assembly table for several months ...

the windscreen stuff used locally seems to be exceptionally "runny" and will wick along very fine cracks.
I have no idea if it is compatible with acrylic.

Mark, you could try talking to a Perspex/Acrylic supplier - maybe there's one in Nowra? The glue that they use dissolves/melts the acrylic slightly - I don't know what it is but I'm pretty sure that ether will do the same thing. All you have to do is find someone who'll supply you with some ether.....

If you have another piece of acrylic around you could try breaking it slightly (hit it with a hammer) and then apply some heat from a butane torch - maybe it might melt into a weld?

Makes sense Ian. Actually, I've found un-thickened West to be very runny, and am pretty sure it is OK with acrylic.

But Brett's suggestion is a good one. No-one in Nowra (or even Unanderra that I can see), but I can call the people in Sydney from whom I've previously bought some acrylic - now why didn't I think of that? That's why we have the WWF of course, so others can sometimes do our thinking for us.

Finding diethyl ether in retail quantity might be a challenge. Last time I had anything to do with that was a(n in retrospect un-necessary) sinus antrostomy/drainage in ~1962. Turned me off rockmelon for decades!

In the years that I was a grad student in Oz, we built all sorts of jigs and fixtures out of perspex (acrylic).
Assemble the unit with masking tape. Drizzle a few drop of chloroform down the seams.
That was plenty to melt the adjacent surfaces and fuse them together.
Come back tomorrow.

The lab bought the raw components for Araldite in 1 liter tins, we mixed our own to go off at 60C over night.
Many were the days to find the araldite oven half full of children's toys undergoing repair.
That leads me to think that maybe you can mix methacrylates with epoxies.

Thanks for the comments RV.

I actually have both acetone and sodium hypochlorite, so could make some chloroform, and would only need a few drops as you remark. The concrete verandah area of the workshop is pretty well ventilated.

However, the epoxy route is less involved, and the mis-alignment of edges might be an issue with a pure solvent technique. Think I'll make a bund with Blu Tack, drizzle it on, and let it soak into and over the defect.

Will get some Blu Tack later this week, and will post photographs of the outcome, satisfactory or not.

I think epoxies will basically work with anything, except poly-olefins.

a few years ago I bought some thin 2mm clear acrylic/Perspex to make model cover boxes. mitred corners etc. I bought from PlastiX at Rockdale and they sold me a little bottle of acrylic bondo clear liquid that you only needed to put a drop on the mitred edge and it seeped in and ran along the join all on its lonesome ad welded the joints together. fantastic stuff, no mess, give them a call (02) 9599 2499.

Once upon a time, the interior rear view mirror fell off the windscreen in my car.
At the dealership, I got the smallest little tube of very runny adhesive to stick the mirror back on the glass.
I'll bet that capillary action would suck that stuff into into the crack.

Plan B: Discount the thing and sell it as a terrarium for Red Back spiders.

Originally Posted by markkr

I actually have both acetone and sodium hypochlorite, so could make some chloroform, and would only need a few drops as you remark. The concrete verandah area of the workshop is pretty well ventilated.

Don't do this. You can also make chloroacetone, which is an incredibly potent tear gas. It's also highly toxic. I have personal experience with it's big brother, bromoacetone, from my previous life as a broke grad student. If it gets too hot phosgene can be a side product too.
Cheers, Robbie.

Firstly Robbie, the last time I encountered a reference to phosgene must have been a good 50 years ago. My father (an organic industrial research chemist) told me what must be the ultimate obscure Dad joke:

oral examiner to none-too-bright chemistry undergrad 'what is the valency of phosphorus in phosgene?'

Now, down to business.

The epoxy repair appears to have worked. I used West 105 resin and 206 hardener. I realise the repair will probably go more cloudy/creamy, but wanted to use what I had.epoxy plug.jpg

After four hours testing with a full tank, no leak. You can see the remnants of the Blue-Tack bund, which I have now removed. The plug is probably 1mm in thickness. The Blu-Tack came off quite easily - left it 48 hours in view of current ambient temperatures.

What I found interesting, is that this epoxy has flowed through the defect. Palpable on the inside is a uniform, smooth, raised ridge, where previously there was a jagged edge. However, it didn't drip; surface tension formed a perfect surface. So, apparently just runny enough. I would imagine that, having flowed through and around the defect on the inside, the epoxy should form a permanent, 'locked' plug from both sides of the acrylic.

Thanks again to all who replied with suggestions; in particular Robbie with his valid warning about amateur chemistry.

Mark

Cloroform is ofted used for "welding" acrilic. Is very liquid and works like methel ethel ketone MEK used for styrene. Is baisicly a suitable solvent that disolves the surfaces its in contact with that will hopefully become one when the solvent evaporates. Would try this on scrap first to chech for discoloration, fogging or distortion. As for getting some? have heard that some chemists will supply (dont have a ballaclava and a roll of duct tape hanging out of your pockets)