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Plastic cases that go sticky

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Circlotron:

--- Quote from: Circlotron on February 25, 2024, 05:32:13 am ---
--- Quote from: AndyBeez on February 24, 2024, 08:50:09 pm ---So it might be interesting to see what happens if a sticky case is exposed to strong UV light - is the degradation re-reversible?

--- End quote ---
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.

--- End quote ---
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:

--- Quote from: Circlotron on February 25, 2024, 08:52:31 pm ---
--- Quote from: Circlotron on February 25, 2024, 05:32:13 am ---
--- Quote from: AndyBeez on February 24, 2024, 08:50:09 pm ---So it might be interesting to see what happens if a sticky case is exposed to strong UV light - is the degradation re-reversible?

--- End quote ---
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.

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

--- End quote ---
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 8)


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 :D

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  :box:

5U4GB:

--- Quote from: Zero999 on February 25, 2024, 05:56:49 pm ---
--- Quote from: rdl on February 25, 2024, 05:24:59 pm ---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.

--- End quote ---
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.

--- End quote ---

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".

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