Re-edging 1500Al-1?

[S.O.Stefansson]

Fellow JBL enthusiasts,I have a pair of K2 S9900, I believe they are from 2011. My question is on the rubber edges of the woofer 1500Al-1, they are no longer completely black, but rather dark greyish. I uploaded a couple pictures. Anyway, is this to be expected? They feel fine, neither stiff nor sticky. Should I just go ahead and don't think of this, or should/can they be replaced (re-edged)? Thanks and best wishes,Sigurd Stefansson

[Earl K]

I would certainly put re-edging out of your mind for the time being.
- As far as I'm concerned, the color change is normal for aging rubber compounds.

You might want to research if there are any "rubber rejuvenation" compounds ( from th car industry as example ) that can bring back the original black color with out "attacking: the rubber.

1audiohack ( LHF member ) bought Butyl Rubber Surrounds from Japan some years back.
- I believe he used them to Re-edge some 2234h woofers ( I also believe that the measured Fs was just like the Foam originally used ).

1audiohack's Thread (https://www.audioheritage.org/vbulletin/showthread.php?38253-2234-Butyl-Surrounds-from-Japan)

:)

[DerekTheGreat]

Thank you for the link, Earl!

Great read, I hadn't seen it before. Makes me regret the foams I just put on my 2215's.

[Mr. Widget]

I would certainly put re-edging out of your mind for the time being.
- As far as I'm concerned, the color change is normal for aging rubber compounds.
+1

DO NOT ATTEMPT TO FIX THESE WOOFERS!!! They are essentially unobtainium and if you do any work on them, the likelihood of a positive outcome is low.

I'm pretty sure this is purely a cosmetic issue. JBL used a foamed rubber that is called EPDM. You should find out if there are cleaners for this exact type of rubber that will not damage the rubber or shorten its life.


Widget

[christo]

+1 DO NOT ATTEMPT TO FIX THESE WOOFERS!!! They are essentially unobtainium and if you do any work on them, the likelihood of a positive outcome is low. I'm pretty sure this is purely a cosmetic issue. JBL used a foamed rubber that is called EPDM. You should find out if there are cleaners for this exact type of rubber that will not damage the rubber or shorten its life. Widget Mine looked like that a few years ago I just use a damp terry cloth rag and very carefully wipe the rubber. They look like this now. I did Google EPDM Cleaner and found the following - My advice is only use a damp cloth with water don't bother with any cleaner - as if there are issues there is no way back!

[Mr. Widget]

Good feedback!

Widget

[turnitdown]

Continuing with the automotive product line of thinking...there is Back to Black made by McGuires that will dress the rubber without further oxidation. I'ts cosmetic only...OR, put the grills back on and fugettaboutit. It's just surface oxidation.

[RMC]

RE Mine looked like that a few years ago I just use a damp terry cloth rag and very carefully wipe the rubber. They look like this now. I did Google EPDM Cleaner and found the following - My advice is only use a damp cloth with water don't bother with any cleaner - as if there are issues there is no way back!

+1, same as christo

Did the same thing, couple of years back, on my 1977 Polk Audio Monitor 5 rubber surrounds and they came back pretty good. These are also essentially unobtainable. The before and after cleaning pics were posted in my BGW Amp thread. I still own and use them (about 47 years now) and i'd do it again if i have to. Can't kiss them goodbye...

Richard

[BMWCCA]

Continuing with the automotive product line of thinking...there is Back to Black made by McGuires that will dress the rubber without further oxidation. I'ts cosmetic only...OR, put the grills back on and fugettaboutit. It's just surface oxidation.

Mothers products makes Back-to-Black.
Meguiar's product is Ultimate Black Plastic Restorer

I could not find the chemical component list for Mothers.

Here's the Mequiar's ingredient list:

Ingredients CAS Number Function
Water 7732-18-5 Diluent
Dimethicone 63148-62-9 Gloss Enhancer
Mineral Oil 8042-47-5 Solvent
Acrylic Polymer
Withheld as
CBI
Thickener
Dimethoxysilyl Ethylenediaminopropyl
Dimethicone
71750-80-6 Gloss Enhancer
Light Aromatic Hydrocarbons 8052-41-3 Solvent
Isopropanol 67-63-0 Solvent
Fragrance Ingredient
Withheld as
CBI
Fragrance
Component
Acrylic Polymer
Withheld as
CBI
Thickener
Aminomethyl Propanol 124-68-5 pH Adjuster
Polymeric Benzotriazole 104810-47-1 UV absorber
Polymeric Benzotriazole 104810-48-2 UV absorber
Bis(1,2,2,6,6-Pentamethyl-4-Piperidinyl)
Sebacate
41556-26-7 UV absorber
Fragrance Ingredient
Withheld as
CBI
Fragrance
Component
Methyl 1,2,2,6,6-pentamethyl-4-piperidinyl
sebacate
82919-37-7 UV absorber
Magnesium Nitrate 10377-60-3 Preservative
Fragrance Ingredient
Withheld as
CBI
Fragrance
Component
Hydroxyisohexyl 3-Cyclohexene
Carboxaldehyde
31906-04-4
Fragrance
Component
Fragrance Ingredient
Withheld as
CBI
Fragrance
Component
Citronellol 106-22-9
Fragrance
Component
Fragrance Ingredient
Withheld as
CBI
Fragrance
Component
Fragrance Ingredient
Withheld as
CBI
Fragrance
Component
Methylchloroisothiazolinone 26172-55-4 Preservative
Methylisothiazolinone 2682-20-4 Preservative

[pos]

Aerospace Protectant 303 could also be an option as it is often used to clean and protect edrum rubber cymbals.

In Europe this product is difficult to find and we tend to use a product called Protectolan for that purpose: https://www.drum-tec.fr/protectolan-cymbal-cleaner-and-protection-100-ml
I do use that one or my rubber cymbals and if I still had drivers with rubber surrounds I would be tempted to try it on them.

There is also this one called CYMPROTECT: https://www.r-drums.com/english/shop/cymprotect/

[christo]

Continuing with the automotive product line of thinking...there is Back to Black made by McGuires that will dress the rubber without further oxidation. I'ts cosmetic only...OR, put the grills back on and fugettaboutit. It's just surface oxidation. Thanks to everyone for their input. I have used all the automotive products mentioned on autos... If my memory servers me correct they are all like a cream, it would be a PIA to and apply and not get it on the paper cone. The Aerospace Protectant 303 looks interesting and if I was to attempt it, I would try this product but… EPDM roof membranes remain stable over time and can have a life expectancy of over 50 years – I’ll be long gone by then. So as “turnitdown” says put the grills back on and fugettaboutit!