Use of MEK to restore idler wheel?

[cooperman]

I have an idler wheel from a BSR 810 deck that has become hardened. I've seen threads that advise the use of methyl ethyl ketone to restore hardened rubber components. I'm wondering what the best way to apply the MEK would be. Should I immerse the wheel in the MEK? If so, how long for?

[RojDW48]

MEK is a rubber restorer used in the offset litho print industry. It is very effective, but immersion is not a good idea. spin the idler and apply MEK with a cloth or cotton bud. Acetone has a similar formula and works quite well - also less toxic !

[Bazz4CQJ]

MEK is an exceptionally powerful solvent; I wouldn't go anywhere near a rubber idler wheel with pure MEK.

Whether MEK in low concentration in some other medium might be be effective is possible.

B

[RojDW48]

Originally Posted by Bazz4CQJ

MEK is an exceptionally powerful solvent; I wouldn't go anywhere near a rubber idler wheel with pure MEK.

Whether MEK in low concentration in some other medium might be be effective is possible.

B

I used it for many years when I was a printer to revive the rubber blanket of an offset litho machine. Acetone, however, is a more sensible domestic option simply because it is so common - nail varnish remover.

[DMcMahon]

Personally I have had minimal success but some people say they have had good success with reviving/softening hardened rubber idler wheels using Glycerin.

David

[GMB]

I would not have expected MEK or acetone to be a good idea for idle wheels.

My understanding is that MEK is a solvent for rubber - but rubber is very cross-bonded so rather than dissolving the rubber it more likely dissolves into it. I think the offset litho folks exploits this to deep clean their rubber sheets and revive the surface.

I have read that acetone will swell rubber worse than MEK.

I have always used alcohols for cleaning rubber - like ethanol, propanol or brake fluid. I did once manage to soften some hardened rubber by soaking in brake fluid.

[emeritus]

Glycerine fixed the surface of the rubber-coated metal disc of the variable speed adjustment mechanism of my Eumic cine projector. It worked by adjusting the radial distance at which a polished steel ball pressed against the rubber on the disc. The rubber had become shiny, resulting in slipping. Smearing the rubber surface with glycerine, leaving it for a few minutes, and then cleaning it off with water, completely restored grip to the rubber.

[GrimJosef]

Glycerine also softened the rubber surrounds on some vintage KEF B139 drivers I had. Their specified free-air resonance was at 25+/-5Hz and, presumably, when new the surround was compliant enough that they achieved this (one of KEF's datasheets says that the typical production spread was +/-2.4Hz). After 40-50 years the rubber had stiffened enough that the resonances I measured were more like 35-40Hz. Gently rubbing glycerine into the surround couldn't quite get them back to 25Hz, but it did get them comfortably below 30Hz.

Cheers,

GJ

[Cathovisor]

MEK, the railway modeller's adhesive of choice for decades as it welds hard polystyrene together beautifully.

It also stuck the tops onto my chemistry teacher's pens exceptionally well, as he discovered when he taught me in particular about ketones.

[DMcMahon]

The only time I have ever used MEK was long time ago, used it to clean ends of ABS pipe before bonding the pipe to ABS fittings using ABS cement.

David

[ajgriff]

Originally Posted by GMB

I did once manage to soften some hardened rubber by soaking in brake fluid.

Might be worth noting the difference between DOT4 & DOT5 brake fluid. DOT4 is glycol based and therefore organic. DOT5 is silicone based and therefore synthetic. Both are designed to be harmless to rubber but I've no idea whether one or the other is more effective at softening hardened rubber (synthetic or natural).

Alan

[fetteler]

I'm sure you all know this but keep brake fluid away from painted surfaces

Steve.

[HG MICKE]

For cleaning and restoring the grip on idlers and pinch rollers I have had great success with Platenclene a product designed for print rollers. I have been using this for nearly 20 years and unlike most solvents it does not degrade the rubber over time.

Colin

[GMB]

Might be worth noting the difference between DOT4 & DOT5 brake fluid. DOT4 is glycol based

Thanks for that. So I was talking about DOT4 brake fluid.

As I said, alcohols (i.e. things with OH groups) seem to be safe. Ethylene glycol and glycerol both fall into that general category.

[theoldtrout]

I've had varying success with MEK on idler wheels and rubber roller. I've found lightly roughing the rubber with wet and dry paper helps the softening process. Be careful with MEK it is carcinogenic.

[kalee20]

Originally Posted by theoldtrout

Be careful with MEK it is carcinogenic.

It's not generally regarded as such!

[emeritus]

I thought the problem with MEK was that if you smoked a cigarette when using it, the glowing end was hot enough to break down the vapour to form a highly toxic gas.

After the potential health problems with MEK were identified, someone produced a plastic solvent called MEK PAK. I forget what it contained, but the bottle said it was not MEK. Nonetheless, I did buy a small bottle of genuine MEK at a pre-Covid model railway exhibition. I actually wanted Plastic Weld (dichloromethane), but the stall only had MEK.

[retailer]

I didn't ever think to use MEK as a product to restore idler wheels - explains why it causes rubber gloves to swell - I've used it many times to help clean laminations when repurposing transformers, it turns even the most stubborn varnish soft so it can be scrubbed off - not a pleasant job - rubber gloves swell and eventually become so soft they break so I've stopped using them. If it is a carcinogen then having it so readily available doesn't make sense, I can get a 4lt tin filled at the local autopaint supplier.

[emeritus]

Just checked the label on my small bottle of MEK. Nothing about it being a carcenogen, just warnings about highly flammable vapour, use in well-ventilated room, do not smoke, vapour harmful by inhalation.

[Goldieoldie]

Originally Posted by HG MICKE

For cleaning and restoring the grip on idlers and pinch rollers I have had great success with Platenclene a product designed for print rollers. I have been using this for nearly 20 years and unlike most solvents it does not degrade the rubber over time.

Colin

What method do you use Colin ,just wipe the rubber or soak etc ?