Modern radios - rubber finish

[newlite4]

Well, after several attempts with all manner of surface treatments I took the plunge and applied cellulose thinners. The white lettering is UNDER the rubber layer which appears to be a sort of clear compound which is deposited onto the black plastic. The base material provides the colour, whilst the rubber layer is a clear finish. Obviously the lettering will be lost, but essential legends could be applied after the layer has been cleaned off. Using cellulose thinners removes this layer rapidly without damaging the plastic underneath, certainly preferable to the original sticky gooey mess.
Neil

[richrussell]

It's used on a lot of car interior surfaces these days - soft plastics give a feeling of quality apparently.

I managed to successfully remove it from a sticky remote control by using liberal amounts of petrol after working up through other solvents. However finding something that'll dissolve the soft coating but not the harder plastic underneath is tricky.

[dseymo1]

Is the coating available for DIY use?
While the stuff can be a pain, it would be handy for refurbishing items which look wrong in glossy plastic.

I think it is very plasticized PVC, i.e. it has a lot of a low evaporation solvent in it making it more flexible. This also (I think, it's been a while) dissolves skin oils into the plastic, hence going 'orrible after a lot of use.

[MurphyNut]

Originally Posted by newlite4

Many sets use this "temporary" finish, Tivoli PAL, Pure Classic, as well as a host of hand helds. I wish makers would stop doing this, it is worse than the Philips "suedette" finish on their early eighties test equipment that over the years turned into a sticky fluffy mess.

Totally agree I have Tivoli PAL, otherwise a very good radio apart from the coating you mentioned, it doesn't last very long. My Pal started looking so bad I removed all coating back to the base plastic and though it looks completely plain it still looks much better than it did.

[Tractionist]

Brethren!

Having recently been unceremoniously presented with a Pure ‘One Classic’ DAB unit – literally ‘fused’ to the plastic carrier bag into which it had been wrapped, by an old girlfriend..... I have spent many fruitless hours attempting to remove this ‘goo’.

Initial attempts involved:

• Jizer de-greaser
• Flash floor cleaner
• Ciz bath cleaner
• IPA
• Lighter fluid [pure petrol]
• Paraffin
• Milton
• Cellulose thinners etc. etc. (the list is long – believe me).

All the foregoing proved futile and merely moved the stuff around – which was what it was doing in the first instance!

But I have now found a very effective ‘solution’ – albeit one that many of you may not be enamoured of!

I used a cold soak bath of caustic soda solution [and I do mean caustic – not ‘washing’]. This reduced the ‘goo’ to a white/emulsified film within minutes and thereafter permitted it to be easily rinsed and wiped off. Presumably foaming oven cleaner would have a similar effect – but I haven’t needed to try this. The plastic sub-striate is unharmed – but this process does necessitate a full case strip [and as you are doubtless aware – this stuff does attack alloy/aluminium].

I haven’t used this process near any legends yet – so I am unsure whether it will dissolve/remove them [they may require masking-off etc.]. However – it is the only thing used to-date that actually works!

If you guys try this – please, please ....... I implore you all to take appropriate precautions i.e. eye protection, neoprene/nitrile gloves, plastic baths etc. etc.

Drastic measures eh? !!!!

[Tractionist]

P.S. I have now finished this 'de-goo' and the results [having polished the set with Pledge] are very satisfactory/pleasing.

The caustic soak did not affect or attack any of the legends - but this comment applies only to this particular set [please be careful with yours and experiment].

It should not be necessary to use anything more aggressive than a soft sponge and paintbrush to remove the 'emulsified scum' after soaking in the caustic bath.

[McMurdo]

Interesting what you say about the caustic.
Below (from B&Q) is a bottle of genuine caustic soda powder.

That particular manufacturer was a client of mine and I used to go and fix the machine that bottled this stuff. I can vouch that it will slowly etch then dissolve metals and certain plastics, as I once fixed a fault caused by a dripping of soda gathering in a loop of extra-flexible pvc covered cable and taking it down to earth when the insulation disappeared.

Maybe one of the chemists would like to expand on that!

(doesn't dishwasher powder contain it too?)

[ms660]

It can make paint brushes go very limp

Lawrence.

[Jon_G4MDC]

Re Post #27.
I'm warming to the idea of calling that "Scum Finish".
It doesn't start that way but that is how it ends up - caustic applied or not!

[G6Tanuki]

Originally Posted by pwdrive

It can make paint brushes go very limp

I've had this happen - nevertheless NaOH is a very effective stripper - I used it to remove the paint from the steel case of my Eddystone 840A some while back - it worked where the current 'environmentally friendly' Dichloromethane-free Nitromors/Rustin's paint-strippers failed.

Just don't use it on anything aluminium- zinc- or magnesium-alloy though!

[Cheapest place to get pelleted NaOH is an agricultural suppliers: dairy-farmers use loads of the stuff to clean the fatty residues from their milking equipment]

[Goldie99]

As "one of the chemists", I would just like to remind the non-chemists that caustic soda, despite it's usage in a wide range of applications, does need to be handled correctly - it's not the most innocuous material, and does need to be handled accordingly, and with caution... it can and will hurt you if abused !

Any commercial product containing significant amounts of caustic soda will carry health & safety warnings, specific to that product. It should also have an associated MSDS (material safety data sheet), although you may need to request it. I'd simply advise anyone using such products to read & heed the warnings - they are there for a good reason....

As to it's ability to 'strip' a 'rubber finish' from something - unfortunately it depends very much upon how the 'rubber finish' is made, and which plastic it's made of.... it won't 'dissolve' plastics as such, but it may degrade / break down their polymer structure, making them removable. Whether it will be very 'selective', and leave the bits that you want, is much harder to predict, and again depends on various factors, not least the plastic(s) concerned. It's a bit like the old dip tanks for stripping paint from furniture, it usually worked, but you never knew quite what you'd end up with until it came out of the tank.... those tanks were typically full of caustic soda.

[Tractionist]

Mmmm ...... Oh Dear - the word has got around!

My Kid Bro' has now presented me with an identical set, and the same lady says that she's going to drop-in two further specimens!

The product that I used/use is basically a bath that I sling all my bar-b-que implements and oven trays etc. 'in' at the end of the season ..... and doubtless dispensed by Kevin's machine!!

I agree with Goldie too .... this material is not 'benign' - a strong alkali is equally as hazardous as a strong acid ... so do be careful.

Anyway - I'll post some 'before and after' pics of the latest Pure [what a misnomer eh?!] 'One' after I've divested it of this disgusting filth!!

[Tractionist]

'Before' and 'After' images as promised:

'Orrible to lovely.

I agree with Goldie99 that caustic soda is very hazardous and very useful. This stuff is dangerous, bags loads of common sense and it is fine, do it outdoors and have a running hose nearby just in case. Much better cold and wet than warm, dry and dissolving.

[vidjoman]

Just a random thought. I have no experience of this so if anyone knows if it'll work or of any hazard please chip in. How about cloudy ammonia? Reason behind the thought - it works if you put a pad soaked with it into a black plastic bag with oven shelves with burnt on grease etc., and leave overnight in the shed or garden and it softens the muck and makes it easy to clean. Oven cleaners often contain either ammonia or caustic soda and do the same job. It's nasty stuff if you breath in the fumes so take care if you try using it.

[Billy T]

Originally Posted by Goldieoldie

Another solvent you could try is the stuff for removing sticky labels. Check first it does not attack the plastic! Pete

I use an orange based product called Desolvit, it has a natural citrus base and it cleans just about everything sticky except a well-filled nappy.

If it is not available in your neck of the woods, Swarfega may be effective as it includes citrus oil, which is the foundation for Desolvit.

Cheers

Billy

[astrouk1]

Regarding the Ethanol comments above for indoor heaters, it's sold as bioethanol for indoor ribbon fires. It doesn't have the nasty colouring additives. The good ethanol is about 96% ethanol & 4% water, I've used it for cleaning for some time. Very good for sticky spots on equipment.

[ColinTheAmpMan1]

As another one of the "chemists" on this forum, there is a product called "industrial methylated spirit", or "denatured alcohol", which you might be able to buy from a pharmacy, if you ask nicely and explain what you want to use it for. It may be available via the web, come to think of it.

The everyday "methylated spirits" contains, along with ethanol (ethyl alcohol in old money), methanol (methyl alcohol: sends you blind, mad and dead), pyridine (smells and tastes nasty, renders you sterile) and a purple dye (methyl violet). These are designed to discourage drinking it.

Industrial methylated spirit lacks the pyridine and the dye, but still has a proportion of methanol to render it inadvisable to drink it.

Any ethanol-based solvent will contain water, as it absorbs it very easily, as indeed does methanol. There is a substantially anhydrous ethanol called "absolute ethanol", but I doubt you will find that too easily. It has to be "duty paid" since it can be diluted with water or whatever and drunk without harm (except for the usual health problems associated with alcohol consumption). Bear in mind that common spirits such as vodka are ~40% ethanol, so attempting to drink neat "absolute alcohol" at virtually 100% purity has extra hazards.


With regard to caustic soda, someone has already quoted the chemical formula as NaOH, but no-one that I have seen has stated its correct chemical name as "sodium hydroxide". It does indeed have uses and hazards in its use. Gloves should always be worn when using it, as it has a property of turning skin into a soap-like material. When this happens, the afflicted person is unlikely to think this is a problem and not bother to wash the affected area with lots of water. This would be a big mistake, as the chemical will continue turning the skin, and indeed any flesh, into the soap-like material. It is (or perhaps was) used in the preparation of soap, actually. As has already been said, it attacks metals, especially aluminium and its alloys, and will liberate hydrogen when doing so. The hydrogen is a serious hazard as it is combustible and explosive when combined with oxygen, either from the surrounding air or from any other source.

As is often said, "if in doubt, don't" and this should be observed when using either of the two products I have written about. Except, of course, for we chemist "smartarses" who do whatever we like <Joke Mode OFF>.
Colin.