Gluing Acrylic sheet

[Sub MandrelParticipant @submandrel]

Hi my stepson is asking if there is anything he can use to 'heal' a crack in acrylic sheet?

Is there something that can be 'run' into the crack? Stopping it spreading is nmore important than appearance BUT A NICE JOB WOULD BE BEST.

Neil

[Sub MandrelParticipant @submandrel]

[Mick DParticipant @mickd41895]

Hi

Acetone is a solvent for acrylics, it will wick into the crack if it is fine.

Regards Mick

[Kevin BennettParticipant @kevinbennett25223]

hi drill a small hole at the end of the crack it will stop it running any further across the sheet

Kevin

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Windscreen repair kit will do it perfectly but a bit expensive to buy .

Unless very complex shape or priceless probably easier to make a new one .

Alternatives :

Make your own filler using Perspex glue and scrap Perspex .

Glue a thin sheet patch on the less visible side .

If thick enough and flat cut the damage out and insert a piece of new sheet .

Michael Williams .

[Sub MandrelParticipant @submandrel]

It's a curved boat windscreen. I suggetsted drilling a hole to stop it propagating, but that wasn't popular. Thsi is the second attempt at a replacement. I'll suggest acetone or weindscreen repair kit. Both should be less than the price of a new 6' sheet of acrylic.

Thanks guys.

Neil

[Chris TriceParticipant @christrice43267]

You won't make an invisible repair. Sorry, but not acetone. You want chloroform or Dichloromethane. If you're in the UK, try EMA in Shepperton (01932 228228) and try there PPC2 solvent cement.Is this surface crazing or a crack all the way through?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Stub Mandrel on 31/12/2012 21:39:44:

I suggetsted drilling a hole to stop it propagating, but that wasn't popular.

Neil

Neil,

With apologies for offending your stepson's visual sensitivity:

Drilling that hole is the most effective part of this repair scheme.

It need only be 2-3 mm diameter, and can be plugged after the screen has been solvent welded.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

If repair fails … this might be of interest:

MichaelG.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Just for interest :

Whilst it is true that drilling a hole will inhibit crack propagation in some circumstances and in some materials it is not the universal cure it is always claimed to be – often the crack will just change direction . It only really works in ductile materials with very moderate stress levels .

Use of the drilled hole in wood is fascinating – sometimes a crack will stabilise for hundreds of years and sometimes it will grow at visible speed and split plank completely .

There is a whole section of stress analysis dealing with crack propagation and a whole branch of NDT for detecting and monitoring cracks . Understanding how cracks form and grow is of particular importance in the Aircraft , Nuclear and Process Chemicals industries .

[Michael GilliganParticipant @michaelgilligan61133]

Neil,

Michael Williams is, of course, correct in saying that the "hole" does not always work.

A couple of things will improve your chances …

1. The hole must be at, or just beyond, the very end of the crack. If the crack extends, even microscopically, beyond the hole then it will give no relief.
2. The hole should be round and smooth. Burnished is best.

Good luck with it.

MichaelG.

[Ian S CParticipant @iansc]

About 15 years ago I donated a turret from an Avro Anson to the Airforce Museum in Christchurch, don'tknow if it was the one used for the resoration aircraft in the museum. The Perspex on it had a number of repaired cracks, all stop drilled 1/16", then a patch fitted over the crack, bolted in place with what looked like 4ba bolts, and fiber/nylon lock nuts, don't think any glue was involved in the repair. Ian S C

[johnp10Participant @johnp10]

When I was at school during the war we used glacial acetic acid to produce clear joints.

Most of the other chemicals were unobtainable then.

It should capillery into the crack easily.

John.

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