Choice of rubber cloth

[SteveS]

I'm in the process of rebuilding the bellows for a former Salvation Army reed organ.
I have been provided with some samples of rubber cloth but am not sure which to use since I haven't acquired an exact match.

The original rubber cloth, as described by a supplier, looks like a denim cloth covered in glue then painted.
Comparing it with the samples I have it doesn't look similar, so it's difficult to say what it is.
The original cloth looks to be painted black on the outside, this has now cracked severely in places.

The original bellows cloth is 0.5mm thick (0.020").

The samples I have are described by the supplier, with thicknesses, as follows:



pneumatic cloth
0.19mm



motor cloth
0.39mm



medium rubber cloth
0.78mm



thick rubber cloth
0.84mm




What are the relative merits of each type of cloth as a replacement for the original cloth?
What can I expect in terms of physical exertion required with these types of cloth?
Which would be best for my application?

Thanks for your help
Steve

[SubBase]

For the tiny feeder bellows, I'd use the thinnest stuff. They will close tighter and thereby gain efficiency. You could use that for the reservoir, too, but the thicker stuff would be a nice upgrade. Depends on whether you want to order two types I guess.

Casey

[SteveS]

Casey - Thanks for the reply.

When you say the feeder bellows do you mean the exhausters?
The exhausters on my reed organ are quite large 12" x 16" and open to about 6.5".

Steve

[PeteKnobloch]

Are you sure that someone didn't paint black rubber paint over the old 90 year cloth to try to seal it 20 years ago? They sold special products to do this some time ago. Most of the thicker cloths used for reservoirs and pump bellows should use rubber sandwiched between 2 layers of cotton cloth front and back. I would go with the motor cloth because it should be around .015 inches in thickness. The thin pneumatic cloth is only coated with rubber on one side of the cloth and won't hold up as long.

Pete

[SteveS]

Pete
Yes good idea it could be that the original cloth was painted in an attempt to seal it.
The cloth itself is a single layer denim-type material which appears to impregnated with a sealant (90 year old rubber or rubberized glue?).
Sounds like motor cloth for the exhausters and medium rubber cloth for the air reservoir.
Steve

[PeteKnobloch]

These thicknesses you are quoting seem to translate nicely into US inches for the standard thicknesses used for rubberized cloth that I use for my player piano work. If the original cloth was coated with rubber later in life, it might have been closer to the motor cloth thickness without the paint. That is why I choose this. With the samples that I have in hand, either the Motor cloth or the Medium Rubber cloth would work just fine. Both being very flexible.

Pete