Plastic cases that go sticky

[Zero999]

I've used citrus-based cleaner with ethanol (sometimes sold as air freshener sprays). It works remarkably well on anything sticky. But be careful around areas that have printed text, labels etc... as it will erase those too.

Be  careful with some plastics. Citrus oil contains limonene which can dissolve some plastics. Most notably polystyrene but also ABS, which contains styrene and is commonly used in consumer goods.

There's even interest in using it for recycling polystyrene.
https://www.chemicalonline.com/doc/new-recycling-process-uses-limonene-to-dissol-0001

[807]

Thanks for all the suggestions, and some interesting info. 

I did try the Cif bathroom/kitchen cleaner, as I had some here. It helped to greatly reduce the tackiness. It is almost "normal" to the touch now, but not quite. There's just a slight bit of tackiness still. Just enough to be annoyingly noticable. I might give it one last go with the Cif, perhaps with the rough side of a washing up sponge this time. I would rather keep the labels intact, but if they get rubbed off then it's not too much of a hardship. I know what the buttons do.

On a similar note, it was mentioned in a previous post about rubber feet. I have a few Racal Dana 1998 frequency counters. A couple of them have metal standoffs at the back to protect the connectors. The standoffs have (or had) black rubber bumpers on them. When I was rearranging my test gear a few months ago, I took the counter off the shelf & stood it up on the floor. When I went to pick it up, it had stuck to the carpet! All 4 bumpers had turned into a gooey mess, like thick tar. Some of it had even run down the back of the counter.

[Gyro]

A dusting of Talc can be used to reduce the residual stickiness, but is a temporary measure as it will eventually soak up the plasticiser and add to the mess.

[tooki]

Besides, plasticizer migration works the opposite of how you think: it migrates from soft plastics to hard ones and softens the hard ones. Plasticizer migration would result in the plastic going soft, not in the rubber going gooey.

Yup.  The worst offenders (as in way too much plasticizer) in my experience are fake "silicone" leads, which are really just overly-plasticized PVA.
The result is that if you keep them in a plastic box, the lead can literally meld into the box, due to the plasticizers.

I assume you mean PVC? (PVA is the water-soluble polymer in white school glue and wood glue.)

I often want softer multi-strand wires, and don't usually need the high temperature capability of silicone leads, so I wouldn't mind them being PVA or some other non-silicone plastic, but the migrating plasticizer makes them annoying to store; they need to be stored away from anything plastic, including cutting mats and such.

FWIW, the softest PVC wires I've found that you can buy today* are the LifY from Kabeltronik. Many manufacturers make LifY, but most use the coarsest stranding allowed under the LiFY wire code. Kabeltronik uses much finer stranding.
For example, for 0.25mm²:
Standard flex LiYv for reference: 14 x 0.15mm
Helukabel LifY: 65 x 0.07mm
Kabeltronik LifY: 128 x 0.05mm

For larger cross-sections (0.75mm² and up) Lapp also resells really nice, super soft LifY.

Wire stranding alone doesn't tell the whole picture, but the Kabeltronik and Lapp are really, really soft.

I have a feeling that newer wires and cables are stiffer in general. To some extent that may be to make them environmentally friendlier, but I think a lot of it is just companies being cheap.

For example: at work, I found three reels of RG-174 cable. Two from Huber+Suhner (Swiss made, currently around $400/100m) and one from Tasker (made in Italy, around $100/100m). Despite both being the same spec, the H+S one is nice and soft, with smooth, flexible PVC insulation, while the Tasker one is stiff, with rough, matte, inflexible PVC insulation. The Tasker's insulation is admittedly easier to strip, but for test leads and the like, I have to use the H+S. I'm not sure why the flexible PVC would be more expensive, but it must be...


*At work I have a few old spools of Swiss-made Soflex PVC wire that is super-flexible. It also uses the 128 x 0.05mm construction. But the company that made it was sold multiple times over the years and as best I can tell, hasn't been made for many years, even before the current owner, Nexans, closed the Swiss wire plant. Nexans doesn't appear to super-flex wires at all, they seem more focused on electrical installation and transmission.

[AndyBeez]

... All 4 bumpers had turned into a gooey mess, like thick tar. Some of it had even run down the back of the counter.

I feel your pain! It seems that this type of 'rubber' turns into a crude oil slick, just because it can
This is also a self-destruction failure mode for drive belts inside 1980s cassette recorders.

A dusting of Talc can be used to reduce the residual stickiness, but is a temporary measure as it will eventually soak up the plasticiser and add to the mess.

Talc is very good for capturing the gunge before it's scrapped off using a dead bank card. I tried sawdust, but this just makes a mess on the bench

Despite the soft-feel coat being prevalent on many electronic devices made in China over the last 25 years, there is little information around as to what it is. One source suggested the material is a type of organosilane acrylate which, after application to a hard plastic surface, is 'baked on' using strong ultra violet light. This is when the soft touch surface texture forms. So it might be interesting to see what happens if a sticky case is exposed to strong UV light - is the degradation re-reversible? Interestingly, the soft surface is meant to be inert to solvents, detergents and alcohol. Which is why it is recommended for use in sanitary sensisitve consumer products like children's toys, phone cases, wearable tech and even, haptic toys for adults

Below, this is a pair of magnetic cupboard lights that are suffering severe degradation. In fact, they are so sticky, they can stick to the side of the fridge without using the magnets! I will clean them up over the next few weeks and hopefully report back. At time of writing, I have the sticky shells inside a bag of talc, which should help to soak up the worst of the crap. On the photo, see how the colour from the black plastic button has migrated into the sticky surface. Some weird chemistry going on.

[Gyro]

I think I mentioned it once before in another sticky goo thread, but I have a Logitech Harmony remote that suffered rubber breakdown on the rear surface. I completely removed the coating with meths to reveal... another, solvent resistant, Logitech logo. Now that's thinking ahead!

[Halcyon]

I think I mentioned it once before in another sticky goo thread, but I have a Logitech Harmony remote that suffered rubber breakdown on the rear surface. I completely removed the coating with meths to reveal... another, solvent resistant, Logitech logo. Now that's thinking ahead!

It's almost as if they knew/expected their product to degrade in this way.

It reminds me of a pair of running shorts I bought. The laundry tag literally says "Designed to fade".

[Nominal Animal]

I assume you mean PVC? (PVA is the water-soluble polymer in white school glue and wood glue.)

Right.  I'll be in that corner there stuffing crayons in my nose and eating wood glue.   

[Circlotron]

So it might be interesting to see what happens if a sticky case is exposed to strong UV light - is the degradation re-reversible?

I've got a USB stick with this very problem. I've put it in the EPROM eraser for 1 hour and we'll see what happens.

[5U4GB]

I just had a quick look at a bottle of DIY store stuff that I have in the garage. The caution label says "contains Ethanol UN1170" but no mention of Methanol or complete ingredients list. Yes, purple in colour with distinctive smell. Sold for spirit lamps / stoves, hard surface, and glass cleaning, de-greasing etc.

It depends on the country, "methylated spirits" here is almost pure ethanol with a tiny amount of denatonium benzoate added to make it unpalatable.  There's zero methanol content, which would make it poisonous.

[5U4GB]

If cleaning with alcohol (most should be fairly plastic safe) and detergent doesn't work, then you could try covering it with a lacquer, to encapsulate it.

I wonder if Penetrol would work for this?  It's sold as a flow additive for oil-based paints but if used by itself it penetrates into whatever it's applied to and then when left for a week or so it forms a hard varnish-like surface.  Petrolheads swear by it for protecting rusty surfaces from further rusting, I've used it on rust-prone workshop tools to prevent the rust in the first place.

[5U4GB]

On a similar note, it was mentioned in a previous post about rubber feet. I have a few Racal Dana 1998 frequency counters. A couple of them have metal standoffs at the back to protect the connectors. The standoffs have (or had) black rubber bumpers on them. When I was rearranging my test gear a few months ago, I took the counter off the shelf & stood it up on the floor. When I went to pick it up, it had stuck to the carpet! All 4 bumpers had turned into a gooey mess, like thick tar. Some of it had even run down the back of the counter.

Ugh, I've got some late-90s electric equipment that's done the same thing, it looks like the original material the feet were made from was chocolate mousse.

And some slightly exotic gear from the mid-90s where the manufacturer discovered, some time after they shipped it, that the adhesive on the labels they used would break down over time and eat through the metal enclosure.  Last I heard they had stacks of them in a climate-controlled warehouse somewhere.

[Zero999]

If cleaning with alcohol (most should be fairly plastic safe) and detergent doesn't work, then you could try covering it with a lacquer, to encapsulate it.

I wonder if Penetrol would work for this?  It's sold as a flow additive for oil-based paints but if used by itself it penetrates into whatever it's applied to and then when left for a week or so it forms a hard varnish-like surface.  Petrolheads swear by it for protecting rusty surfaces from further rusting, I've used it on rust-prone workshop tools to prevent the rust in the first place.

I have no idea. I've never heard of it, until now. Going from what I found using Google, it might attach some plastics, but can't be sure either way.

[rdl]

I wouldn't use Penetrol as a cleaner. That's not what it's for. It's some kind of modifier for oil-based paints. It contains only 70% volatile by volume (which appears to be mostly petroleum distillates) that means a large part of it is some kind of solid, or non-evaporating material.

[Zero999]

I wouldn't use Penetrol as a cleaner. That's not what it's for. It's some kind of modifier for oil-based paints. It contains only 70% volatile by volume (which appears to be mostly petroleum distillates) that means a large part of it is some kind of solid, or non-evaporating material.

I think that's the ides: the solid, non-evaporating material will remain on the surface, sealing in the goo. The trouble is the other stuff might attack the plastic.

I was thinking of a spray on lacquer which will dry very quickly and the solvents should evaporate before having chance to damage the plastic.

[Circlotron]

So it might be interesting to see what happens if a sticky case is exposed to strong UV light - is the degradation re-reversible?

I've got a USB stick with this very problem. I've put it in the EPROM eraser for 1 hour and we'll see what happens.

It seemed to improve ever so slightly. Maybe. So, yeah, nah.

[jpanhalt]

If the stickiness is due to UV exposure, you are not reversing that "degradation."  If what you are seeing is real (what were your controls?) you are seeing additional UV "bleach" (i.e., destroy or change) what was made initially.  UV irradiation can be used synthetically, but those reactions need to be monitored/limited so as not to go past the desired point.

I do not think stickiness from such coatings principally is from UV.

 

[AndyBeez]

So it might be interesting to see what happens if a sticky case is exposed to strong UV light - is the degradation re-reversible?

I've got a USB stick with this very problem. I've put it in the EPROM eraser for 1 hour and we'll see what happens.

It seemed to improve ever so slightly. Maybe. So, yeah, nah.

Yah, nah, maybe I wonder how many Joules per square meter of UV + days/weeks, it will take to harden off completely?
We might need one of those industrial steriliser death ray lamps - as seen on @BigClive


YouTube has a few videos demonstrating sticky coat removal: Most involve mechanical rubbing with copious quantities of neat acetone. This does have positive results, but I think the rubbing action is doing most the work, rather than the acetone reconstituting the surface texture. Personally, if you want your lab to smell like a Vietnamese nail bar, then go ahead. Just don't switch on anything that makes sparks

There seem to be two families of soft plastic coating. An inherently soft plastic that's used in higher end devices, such as those Logitech controllers and mice. This plastic seems to sweat plasticiser after a few years of use. In worse cases, it might turn into chocolate mousse. Then there is the soft touch coating used on budget devices, which is aerosol deposited and hardened with UV. It's so cheap, it is not intended to last.

Maybe I'm just being cheap, but I'm experimenting with a safe way of removing the spray on coating: after 24 hours, the talc has captured a lot of the gunk. The talc and gunk mix can be sloughed off without leaving a sea of sticky globs. However, there is still a very thin sticky layer on top of the plastic, which I will treat with more talc. This is rather reminiscent of a car body restoration, where every piece of paint has to be removed. There is no chemical strip option and grit blasting might be too aggressive on a computer mouse.

+EDIT+ I was told of automotive soft touch spray paints which use a chemical activator, rather than UV light. This is a spray paint product available in the UK called Tactile. The link is to the supplier's material safety datasheet PDF, which gives an insight to the chemistry used in soft touch finishes
 - https://cdn.shopify.com/s/files/1/0552/4006/5107/files/MSDS-Tactile-Spray-Can-CP-Ltd-2022.pdf?v=1645203245

[armandine2]

https://www.eevblog.com/forum/chat/overpriced-stuff/96/

.. leave product reviews to shame the manufacturers 

[5U4GB]

I wouldn't use Penetrol as a cleaner. That's not what it's for. It's some kind of modifier for oil-based paints. It contains only 70% volatile by volume (which appears to be mostly petroleum distillates) that means a large part of it is some kind of solid, or non-evaporating material.

I think that's the ides: the solid, non-evaporating material will remain on the surface, sealing in the goo. The trouble is the other stuff might attack the plastic.

Ah, good point, I've only seen it used on metal.  If you want to see a typical off-label use of this kind, google "rat rod".

[Black Phoenix]

I know very well that "rubbery premium touch" on plastics that go bad with time and it is a pain to remove. I have an AKG K845BT headphones who the plastic parts are covered in such soft touch coating that was a sticky mess after some years of use.

My solution was to basically strip everything to the plastic, apply a coat of plastic primer and then 3 coats of black matte paint, together with a light coat of clear matte.

Now it looks even better than before and way stronger than before. Now the other problem I need to solve is that it randomly turns off and on during use, but since it has a 3.5mm jack I can just simply plug in the cable and use it wired until I have the patience to solve his problem.