is there anything to help dried/old paper surrounds?

[freddi]

got some very dry vintage RCF 12" whose paper surrounds look and feel very brittle - one has a crack - they don't seem to have been doped like CTS, etc. - is there any nearly idiot-proof treatment which will do more good than harm?

[marchel]

I think the surround needs replacement, I dont think there is anything you can do about it short of a replacement.

[freddi]

imo they have "some" life left - a suitable coating might extend life a bit - one speaker has a few radial cracks in the paper surround--- these are 12" drivers with a horrendous 2.5 ohm dcr , fs ~62, qts in the 0.7 region - dust-cap is interesting as is an inverted cone

[tomtt]

rubber cement might be, what you may be looking for.







74

[Cal Weldon]

Tom, what is the base solvent in rubber cement? I am wondering if he might want to cut it back a little before applying?

[e_fortier]

Not that I know them but give these guy a call;

http://www.simplyspeakers.com/2doityourself.htm

Eric

[tomtt]

Originally posted by Cal Weldon
Tom, what is the base solvent in rubber cement? I am wondering if he might want to cut it back a little before applying?

copy and paste from wiki -


Rubber cement is an adhesive made from elastic polymers (typically latex) mixed in a solvent such as acetone, hexane, heptane or benzene to keep them fluid enough to be used. This makes it part of the class of drying adhesives: as the solvents quickly evaporate, the "rubber" portion remains behind, forming a strong yet flexible bond. Often a small percentage of alcohol is added to the mix.

Formula

The formula for rubber cement varies according to its targeted application. Those commonly used in office and art applications are usually non-vulcanizing and seldom differ between brands. However, they have been reformulated over time due to concerns over the toxicity of the chemicals involved, especially in regard to its use by children. Consumer-grade products generally no longer contain benzene because of its link to certain cancers. Instead, they tend to be based on less toxic solvents such as n-hexane and n-heptane.


Rubber cement based on n-heptane is very popular and ubiquitous in the United States, but is generally unknown and unavailable as a consumer product in the UK and some parts of Europe, possibly due to the severe fire hazard of that formulation. A similar solvent based product called "Cow Gum" was common in the UK, but is no longer in production. Current solvent based options include Marabu-Fixogum and Platignum "Studio Gum" which are marketed in the UK and Europe.


note a difference here -


For tire patching, shoe repair, and other industrial applications, vulcanizing formulas are preferred. These contain chemical additives which enable them to cross-link and harden into a tougher, more resilient form.




http://en.wikipedia.org/wiki/Rubber_cement



132

[HK26147]

nearly idiot-proof treatment

It good to know that benzene is no longer used.
Still I'd be afraid about aggressive solvents and old brittle surrounds.
If the surrounds are not dirty or can be cleaned without further damage,
I would try a benign latex caulk, or a flexible fabric glue ( thinned ).

But like marchel said: replacement might be the best option.

[chrisb]

Originally posted by HK26147

It good to know that benzene is no longer used.
Still I'd be afraid about aggressive solvents and old brittle surrounds.
If the surrounds are not dirty or can be cleaned without further damage,
I would try a benign latex caulk, or a flexible fabric glue ( thinned ).

But like marchel said: replacement might be the best option.

how would you propose to replace an accordion pleated paper surround?

Foam or even synthetic rubber surround kits would most likely be available in an appropriate size, but very careful cutting would be required to remove the existing, damaged surround, and more importantly, the compliance and other characteristics could be significantly affected by the new material.

If the damaged area is accessible from both sides, why not try something like patching with a sandwich of rice paper and diluted Weldbond or puzzlecoat (PVA white glue), applied with Q-tips.


You could also check with someone who specializes in repairs and restoration to vintage drivers. They may be able to recommend materials for reconditioning /doping , or have alternate methods for repairing torn pleated surrounds.

http://www.thespeakershop.com/home/speakerrepair.html

[HK26147]

how would you propose to replace an accordion pleated paper surround?

Ideally, from one of several sources that carries pleated surrounds.

You do raise an issue that I also wondered about - What are the differences ( if any ) from one vendor's surrounds/kits vs another.
How much influence does it have, since it is half the suspension system?
And I wonder if we as DIYer's put more thought/concern into it than the original manufacturers.
Unfortunately there are no soft/medium.stiff options, I know of.

The comment "very brittle" made me think ( that while it may have a small tear ) it would be like patched a sun cracked worn out tire - Fix one spot apply power and another tear appears.
Is the current compliance and resiliency ( of a a brittle surround ) anything like it was when new anyway?
A surround that is torn/not shot - I have ( as chrisb said ) used small pieces of tissue/wrapping paper and soft white ( fabric glue )