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MG TD TF 1500 - Melting Steering Wheel

Over on the Y board, there is discussion about melting steering wheels following the polishing of them. Admittedly, it was a while back.

Has anyone experienced this problem?

Cheers
Stuart
Stuart Duncan

Stuart, are they referring to melting when the owner gets over ambitious with the polisher and compound..or melting experienced for some reason after the cleanup and polishing process?
I have seen other polishing projects go sideways with too much speed and pressure on the pad while polishing. I have not seen steering wheels affected in any other manner. When polishing be patient, begin with the most course compound and gradually work toward less aggressive compounds. You should not have any problems.
Regards, Tom
tm peterson

Tom
The following is an extract from Rodney/Rocky, of Virginia, post on the Y BBS.
"Many years ago, I was waxing my YB when I decided to spruce up my steering wheel rim. It was dull and ratty, I assume the wheel was original to the car.
I wiped the rim with the wax applicator. I believe I was using Turtle Wax, but this was over 30 years ago.
To my complete surprise the plastic liquified and dripped away over the course of a week or so.

I am a degreed chemist and know of no plastic that can dissolve like this: with no additional solvent the polymer apparently "unzipped" and reverted to monomer units. I recall the liquid did have a distinctly organic odor.
............
I ended up with the bare metal core of the wheel rim. Fortunately, as the wheel is the same as that used on TD/F's and many other contemporary cars, I was able to acquire a new one.

Stuart
Stuart Duncan

Stuart, Thank you for the follow up. 3 words:that is crazy
Regards, Tom
tm peterson

Stuart, Dave Hill wrote elsewhere about the chemistry of the original wheels. They are not strictly 'plastic' as we know it. A combination of celluloid and nitrate as a plasticiser was used.

"The originals were made from celluloid and suffer from celluloid rot involving loss of the camphor plasticiser and other degradation processes, which cause shrinkage and cracking. The marbled effect was achieved by loose blending of two or more colours of celluloid, with alcohol as an additional softening agent during processing. The alcohol is driven off before use."

So if the polish or cleaner used had an alcohol base could that be the reason for the breakup of the wheel?

I have restored mine but put it away as the high heat here in summer would lead to more cracking.
M Hyde

Sounds to me that whatever was used to polish the rim contained a fluid that is a good plasticiser for celluloid. It wouldn't be alcohol because owing to high volatility it wouldn't be around long enough to do anything. Its more likely to be a phthalate or some other ester. The process isn't melting as it doesn't involve heat, from what has been said.
When I was a PVC chemist many years ago, I observed the effect of phthalate plasticisers on nitrocellulose first hand. We stored some coloured pencils in a flexible PVC sleeve and in a few days the coloured nitrocellulose paint on the outside of the pencils was turned to goo by migration of plasticiser (phthalate) from the flexible PVC. The problem was overcome by using much higher molecular weight plasticiser that didn't migrate.
Celluloid is made from nitrocellulose and a plasticiser - traditionally camphor, but can be phthalate based
Dave H
Dave Hill

Yep, had one melt on me...started dripping on the upholstery...what a mess. Not sure what caused it other than trying to clean it. Mine had gone greyish and I was trying to restore the black color. Sorry, can't remember what I used but it was probably a combination of a number of cleaners.
Gene Gillam

This thread was discussed between 10/02/2023 and 16/02/2023

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