un-deforming rubber parts

[Jules Richardson]

Can anything return deformed rubber parts back to original shape? (perhaps just application of heat, but what about castor oil or some other magic?)

Background: The rubber weather-stripping around an exterior door at work has been squished in one spot because someone added a metal strip to the entire width of the door, which encroaches into the space occupied by the weather-stripping when the door's closed. Result is the appearance of a little triangular air gap above and below the metal strip when the door's shut, which is rather noticable when it's bastard cold outside (it was

-31C last night).

I can cut the metal strip back by a 1/2" or so easily enough so that this is no longer happening and the door closes evenly against the frame, but I'm not convinced that the weather-stripping will return to its original shape without some help (and of course maybe it's permanently snafu and I'll end up removing and replacing that portion, but it'd be nice to try a few other options first).

cheers

Jules

[Dave Liquorice]

What happens when you open the door? Though at -31C you probably don't want to do that and the rubber will be rock hard anyway...

Time and warmth might let it return to it's orginal shape but how much deformation are we talking about in relation to the size of the weather strip?

[geoff]

In message , Jules Richardson writes

WD40

[Jules Richardson]

It just remains in the deformed state (and feels quite solid to the touch, although the rest of the strip is still pliable). I expect it's been subjected to this for years.

Well the strip is probably about 12mm uncompressed (i.e. door open) and squashes to 9-10mm with the door closed - expect in the region where the metal strip on the door interferes, which is "permanently" deformed down to about 5mm.

I've heard of castor oil helping to rejuivenate dried-out rubber, but I don't know if it (or anything else) is any use for something which has been deformed due to compression. It may be that replacement is the only option.

cheers

Jules

[harry]

If you can get the part out. Cooking it up in hot water for half and hour or so helps.

[Terry Fields]

A good idea providing the rubber is oil-resistant, such as nitrile. If it isn't, the door might will need to be re-sealed.

The oil and solvent in WD will cause the rubber to swell, and it might be enough to return it to its original profile (provided the outside temperature is warm enough). Gentle heat from a hair-drier might help the process, but it will take time and perhaps re-application.

I had a leaking garage roof where the felt had split; applying WD 40 a couple of times a year kept it watertight for some 10 years, until a new neighbour wanted his garage re-felted, and as they were attached we had both done at the same time.

[Dave Plowman (News)]

I've heard of some using car brake fluid for the rubber surrounds on speakers to restore flexibility. Not tried it myself, but it's cheap enough to try. The ordinary, not silicone, stuff.

[geoff]

I'm not just a pretty face, you know

[Grimly Curmudgeon]

Brake fluid contains seal sweller; brush some on.