Sticky stuff in octave mandolin case

I noticed a while ago that the sides of my octave mando had a sticky-ness on the surface, but it's something I can't see. I'm fairly sure that I can remove it using naphtha (lighter fluid?), but it apparently is also on the inside of the case, on the plush interior, just on the sides. I don't know what it is, or how it got there, and there is nothing you can see, no discoloration or anything, but I can feel it with my hand. Can naphtha be used on the plush interior of a case? Anyone have any experience with this sort of thing?

Jack

If you use Naphta on the plush it will/can dissolve the glue for the plush, so it will loosen and maybe the glue will penetrate the cloth even more. So be very careful.
I Have used Naphta for removing the cloth, modify the foam and then stick the cloth back on.

Of course you could just wipe it with your hand and then see if you can get it off your hands with just soapy water? Use the mildest solvent first.

It’s not hydro-gel? That stuff seems to be everywhere nowadays.

Jack, is it affecting the finish on the instrument? It the plush contains vinyl and the finish is lacquer you might see some reaction.

Does anyone in your vicinity do artwork, or photo mounting, and use a spray-can based adhesive? In my experience, the overspray from these cans can get lofted easily into the room air and deposited absolutely everywhere, resulting in sticky surfaces. If your case lid was open, it would get inside.

A different kind of sticky surface can result from folks in the kitchen doing some frying in skillets, which can also throw up micron-scale aerosols of cooking oil. If any of microscopic droplets of oil land on your case, they can subsequently oxidize and produce a very sticky substance.

Both of these kinds of droplets can be removed by many kinds of organic solvent, such as ethyl alcohol, isopropanol, or naphtha. Treat a cloth (like a microfiber cloth or soft towel) with this solvent and then try wiping a sample area of the outer case surface. If it works, you can also use this approach on the plush inside of the case. Just don't apply the solvent directly to any case surface. That way, it can't soak in too deeply and affect the case adhesives and all that.

Do you know what finish is on the instrument? There have been finishes that had this problem; becoming "sticky". Major manufacturers have files lawsuits and the finish companies have had to pay. If your instrument was made by a maker who used such substandard finish and received a settlement, you might have a warranty claim (if you are the original owner).

Some great replies, thank you all. Poul Hanson, thanks for the warning about using naphtha on the plush; I don't think I'll chance it. The instrument is by William Petersen, made in 2002 I believe (I bought it used) so I don't know what kind of finish it is. But the finish doesn't seem to be harmed, just sticky, and only on the sides. No art sprays are being used here, and the case is closed when I'm not playing the instrument. I might try the naphtha on the instrument, and alcohol on the plush in the case. Simon mentioned hydro-gel - I have no idea what that is. I'll have to google it. I might try just soapy water first. It's a mystery to me where this stickyness came from.

jack

Sorry Jack, I don’t know the name of it in English, it’s a water alcohol gel mix that’s used in hospitals, and now everywhere, by everyone as a sterilizing gel for the hands. Can leave a mess on instruments.

Main ingredient, couldn’t find the actual stuff itself: https://en.m.wikipedia.org/wiki/Hydrogel

So basically it's hand sanitizer. I don't think that's what is in my case, as I discovered the problem sometime last year, before I was using hand sanitizer.

An update: I cleaned off the instrument with the lighter fluid, came out fine. Then I used Dawn detergent and warm water on the inside of the case, using the suds on a sponge, not a lot of water. I rinsed off the soap with a wet sponge, wet only with water. When it dried one side was still a little sticky so I used rubbing alcohol on a cotton pad to clean it further. After the case was dry I put the instrument back into it and everything seems to be fine now. I still don't know what the sticky stuff was or how it got there.

Jack

if it were me I think I'd leave the instrument out of that case for a good while to see if either develop the sticky issue again-might help figure out if its the instrument or the case causing the issue.

d

Good idea. I can leave it on the stand for a while.

Jack