Materials sience/ chemistry question - Can rubber f*** up PVC surfaces? Or maybe, what can?


Apr 3, 2016
Hi there fellow Citizens,

I've gotten myself a bag specifically meant to put tin whistles in, which then I did. After having them in there for over 8 months, I someday noticed, I haven't done learning/practicing to play them for some time got them out and noticed the PVC whistles didn't seem to like it.
One whistle in particular - made of ivory white CPVC with a machined surface - looks rather bad. It now has areas of grey spots/dots in a diagonal grid pattern, where it probably was in tight contact with the bag's fabric. That pattern you can also feel with your fingers. In the narrow area of the seam of the bag's whistle slot, the whistle instead got discoloured to something yellow or orange or brownish, while I at least cannot feel anything with my fingers.

Some black PVC whistles - don't know the type of PVC - with a visually smooth shiny surface, which feels rather grippy - has been bothered, too, but too a way lesser degree. Here I can only find a narrow band of a diagonal grid pattern, which I can only see against the light as spots of dampened reflectivity, that I also cannot feel haptically. That affected area would have sat against the bag's slot's seam.

I asked the merchant, I got the bag from, what chemistry might explain this. They said, they relayed the question to the manufacturer, and asked for a picture, but after that I haven't heard anything for two weeks now.

In the meantime I noticed, that the bag's fabric is seemingly dip-lined with a thin grey layer on the inside. I'm guessing this layer is rubber. Hard to say - the layer is rather thin and the fabric rather stiff in relation.
Now I think this alleged rubber might have bonded with the machined (as in increased surface area by microstructure) CPVC surface, which would explain the grey dots, which I can feel with my fingers. And the discolouration in the areas that touched the seam - not in direct contact to the thin inner lining - might have come from some plastizicer in that layer, maybe?

Maybe someone here might be knowledgable about how to f*** up PVC and can comment. That'd help me, when choosing another bag.

Thanks so far,
After finding out if a PVC whistle is indeed what I thought it would be I thought: I don't have a clue what could be the cause. But a quick search got me here:
"CPVC pipe manufacturers are well aware of the incompatibility of CPVC drain piping toward most hydrocarbon based chemicals and yet they continue to promote the use of CPVC piping for sink drain piping in laboratories."
Who knows, there might be some hydrocarbon based chemicals used in the material of the bag?

It reminds me of my shoes. I got myself some fake-leather shoes and used waterproof spray on them, after reading the label if it was suitable. After it dried I noticed the spray appeared to have removed the black color of the shoe.
When contacting the shop selling the waterproof spray they stated this spray wasn't suitable for fake-leather, only real leather (which I think is a meh argument, as it stated it was for multiple materials not only leather).
When contacting the shop selling the shoes I got in contact with the company making the shoes. They weren't aware of any issues with waterproof sprays and stated any spray for leather should work on their fake-leather to.
So my conclusion there was: I don't know what caused it. But I got a free pair of shoes from the shoe brand, which was nice.
So you might not find out the cause, but maybe you can work out something with the bag company to?
After finding out if a PVC whistle is indeed what I thought it would be
In the context of a bag for tin whistles, by PVC whistle I meant a tin whistle/penny whistle, which is a certain kind of flageolet, that's made of PVC.
So you might not find out the cause, but maybe you can work out something with the bag company to?
That's contrary to what I'm after. The whistle still works fine. It's just a shame it looks shitty now. I want to be able to make certain I avoid something like this in the future. I still want to put my whistles in bags. :)
Thanks for the find. Though I don't know, what's there in synthetic fabrics or rubber (, if that inner layer is rubber, or some rubber-esque whatever otherwise) to be found more or less frequently.