Oh no, not again! Melted Bumpons!

Rick Granick

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One of the pieces hanging in our workroom exhibited melted bumpon symptoms, so I checked it. Sure enough: melted! The thing is, these were ROUND brown ones. We have been led to believe that the problem was confined to the square brown ones, and an isolated batch or two. This piece was framed in the late '70's.
:mad: Rick
 
Just replaced broken glass. Picture has been in the customers garage. Melted WHITE bumpons, never saw them melt before, they were like tub caulking. Got on everything.
 
These are apparently a polyurethane plastic material that deplolymerizes into a sticky goo. I have seen them as “feet” on the bottoms of computers and monitors. All models were the same and purchased at the same time. A couple had the meltdown and left a very sticky goo on the tables. Apparently polyurethane requires a precise chemical, temp and time process during manufacture or it can be unstable. Perhaps the environment has an influence.

Seems to have longevity issues as a foam as well. I've seen the foam surround in older speaker drivers flake away. Camera owners who have an older camera my notice the foam light seals starting to flake. The foam in my 25 year old Ricoh XR-7 35mm SLR is getting a bit sticky and is flaking away.
John
 
I use the felt ones. They don't melt. They are cool. But, they do sometimes just fall off. Still... they don't leave that gooey mess.
 
I never used the brown bumpons but this week I got a report from a customer that a Black bumpon had melted. And it was not the 3m brand but a generic brand from United Mfg.
 
I have had the issue with the round brown, never used the square brown. Switched to the round clear 'cause 3M said they don't melt(!?)
 
I can't imagine the round ones and square ones are actually made of different materials. That would be just plain weird.

I've heard of problems with black and brown Bumpons, but have never actually seen the problem. I've never heard of white Bumpons.

I use the clear. Jim Miller offered a great tip about putting a little square of clear framer's tape, or equivalent, on the corners before you put the Bumpons on. This really does help keep them from getting knocked off.

Melty Bumpons must be the asbestos of the framing world. I can visualize teams of highly-trained technicians going around the country replacing Bumpons before it's too late and cleaning walls when it already is.
 
John: I have had the little rubber feet on the botom of a cordless phone start to melt too. As for the speaker surrounds, that is typical age problem with older speakers, as you mentioned. Did you know you can replace the foam surrounds yourself with an inexpensive kit? I've done it, and it's very easy and effective. Can't remember the name of the supplier offhand, but they were very friendly and helpful too. If anyone is interested, I can look up their name and contact info. Wish I had known about that before I bought new woofers for my old Thiel Model 01's.

As to the melted Bumpon issue, I was the first to bring this issue up a few years back (remember the Hershey Kisses on a Radiator?), and after discussion here and with 3M, I was under the impression that the problem was confined to a bad batch or two of older formula Bumpons. Now it would seem more like a generic, and potentially much more widespread, problem. Ron's Bumpon Squad doesn't sound like such a bad idea.
fire.gif
Rick
 
Rick, Thanks for the tip. I've heard of the repair kits. Those weren't my speakers, but I have a set getting older that are good at the moment. I've heard people using "Foamies" to replace the light seals on cameras.
John
 
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