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DIY: acrylic lid repair

Acrylic Repair Done Right

[Chloroform]
[Italian version]

Product: Chloroform, supplied by local pharmacy
More information: Wikipedia on chloroform
Reviewer: Hartmut Quaschik - TNT Germany
Reviewed: May, 2009

There are often opportuntities to buy old used turntables. Some of them have acrylic lids, and most times these old turntables are shipped by post, not using the original box. The result might be a crack in the acrylic lid.
I always wondered how to repair these things. This picture shows a past attempt with superglue. Superglue is no good for the lid, as the acryl shrinks and does not bond, so I rather wrecked the lid. Look here:

[Don't do this!]

When I talked to a friend about this topic he told me a rather unbelievable story: when he was working as a holiday student at Pink Triangle UK, he used chloroform to bond the acrylic sheets together that form the lid of a turntable. Further reading at wikipedia teached me that it is indeed the right substance to work with.
As chloroform had been used as narcotic substance in dental clinics and hospitals for long years, I was afraid using it at home, but my friend confirmed that as long as you don't inhale it directly, there is no chance of being sedated. Nevertheless we have let the window open when working with Chloroform.

Important saftety information

As chloroform is a harzardous substance, don't use it closed rooms, use it only as described here, and keep it away from children. Store it safely.

Preparations

For an acrylic lid repair, you need only a small amount of chloroform, about 10ml (for US: a third of oz.). Unfortunately, my local pharmacy had no chloroform on stock, and they wanted to let me order a quantity of 1 litre minimum, so I had another friend bring me a small bottle from another pharmacy.
What else: we need some adhesive tape to fix the acrylic pieces, and a tool to apply the chloroform to the acryl. We used the handle of a spoon, but any other suitable tool might work as well.
Very important: if a previous owner of the turntable already tried to repair the lid using more ordinary glue, you have to remove all of this glue first - this can take a long time. Make sure the broken pieces fit together with next to zero gap. Chloroform cannot fill gaps, it just can bond together acrylic parts already touching one another.

Procedure

Use adhesive tape to lock the acrylic parts into position, leaving next to zero gap between the parts meant to be bonded. Take some chloroform with the spoon, err ... tool, then apply let the chloroform flow in the gap. Work along the whole edge. It takes just a moment for the chloroform to bond the pieces, so there is no time to readjust, but you can always break them up along the edge.

[Pink Triangle lid repair]

Result

We successfully repaired an original Pink Triangle acyrlic lid, where the pieces got somewhat loose, then a lid for a Thorens, which had been cracked at the previous owner's location, and which someone has tried to repair with ordinary glue. All things worked afterwards, the Pink Triangle lid was like new, and the Thorens lid was fully functional again, but optically looked still bad, due to the tried repair.

[Thorens lid repair]

Conclusion

If you have a cracked lid, this method is worth trying for yourself.

Added December, 2009

A thoughtful reader, Roberto Amato from Italy, wants to share with us his long-term experience with using chloroform for glueing acrylic material. He not only found a better way appplying the chloroform, he also points to a solution filling the gaps of broken parts.

The first thing is that the best way to pour chloroform instead of a spoon is to use a hospital plastic syringe with its needle on (you can buy it together with the chloroform!). The plastic the syringe is made with does not melt, and neither does the soft black sucker inside. The needle can be positioned very precisely, especially at the 90 edge of two acrylic pieces. You can use just the quantity you need, can suck chloroform from the bottle easily and you can keep the syringe full of chloroform, without the chloroform evaporating, for a long time. Very handy. It allows you to work carefully with plenty of time at disposal. When you are done, can put back in the bottle what's left in the syringe.

The second thing is that you can prepare (in a separate bottle) some chloroform with some small pieces od acrylic inside. It takes some time, but they will melt completely and make the liquid somewhat dense. This mixture can be then be used to fill cracks or gaps in not so even materials. If you allow the pieces to dry throughly you can pour again the mixture how many time you like, filling the gaps little by little, adding some more acrylic material each time. Depending how dense you made the mixture, it can still be picked up with the syringe. Best regards, Roberto Amato

Copyright © 2009 Hartmut Quaschik - www.tnt-audio.com

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