Lans-a-loy Repair Question

[Oldmics]

Gentlemen

We have some pretty creative minds on this forum so heres todays delema.

Looking for some sort of chemical to melt and then refuse Lans-a-loy surrounds.

Have a few units that have small separations but not split all the way thru.If I could liquify and move some of the existing Lans-a-loy material around and then have it dry in its new location as a patch,it would be a beautiful thing.

I"ve tried most of the usual household and reconing chemicals with no success.

M.E.K. doesnt work and neither do lacquer thinner,wd-40,alcohol and some chemical cleaners.I just thought about ammonia and will try that.


Any suggestions ??????


Oldmics

[aust-ted]

Hi Oldmics

We need to find out the chemical composition of Lansalloy. Once we find that out it should be easy to determine what will bond to it. I have a friend who is an industrial chemist who may be able to help out.

Regards
Ted

[Oldmics]

Since you can use brake fluid to reactivate stiffined Lans-a-loy,I would assume that its a petrochemical.


So what would dissolve a rubber band?

Oldmics

[aust-ted]

Since you can use brake fluid to reactivate stiffined Lans-a-loy,I would assume that its a petrochemical.


So what would dissolve a rubber band?

Oldmics

Yeah but we need to know which petrochemical. Anyone got an idea? Polyethlene? polyproplyene? etc

Regards
Ted

[Mr. Widget]

Is this for you or a paying job? If it is yours, ship it to me and I can most likely fix it.

Widget

[Earl K]

Hi There,

Looking for some sort of chemical to melt and then refuse Lans-a-loy surrounds.

- Have you tried applying heat ? ( a chemical catalyst isn't necessarily the only sort needed )

- I realize you're hoping to discover that this stuff can be treated as if it was PVC where you can add acetone/? ,,,,which chemically melts it ,,,, and then have it reconstitute itself once the acetone vapourizes .

- I think LansaLoy is a lot closer to rubber than plastic, so I'm pretty sceptical about this whole process . Rubber turns back into a shapeless glob that needs reforming ( vulcanization ? ) after it has been heated .

- I'll think some more about this .

[aust-ted]

Earl

If we knew for sure it was a butyl rubber then we could easily work out what bonds to it

Regards
Ted

[Earl K]

Hey Ted,




- I have a few le14a(s) with the LansaLoy surrounds. Some are eventually destined for refoams since I "pooched" a few rehabs .

- My first LansaLoy rehab was of a surround that had 2 concentic splits that circled around @ 80% of the surrounds' circumference ( this appears to be similar or worse than Oldmics situation ). I chose to DOT 3 Brake Fluid the material and then apply a thinned down, silicone-based skin over these splits in the LansaLoy. This worked well and I ended up with a Fs in the low 20s. This would still be my first choice ( apart from refoaming ) if confronted again with a similar situation .

- FWIW ; Zmax on these older surrounds is considerably lower than the newer foam types with a lower Q ( a broader impedance skirt ). This lower Zmax is somewhat electrically similar to throwing a conjugate resistor across the woofer . ie , it aids in dampening . That is the singlular most important reason that I try to maintain these old surrounds ( apart from just being lazy ).

- Some excess/surplus LansaLoy is needed so someone can experiment within a crucible ( to test this melting theory ).
- Bunsun Burner anyone ?

[Zilch]

What we REALLY need is a suitable butyl surround like LE14H-3.

Ask a volume reconer/refoamer to save Lans-a-loy surround fragments for experimentation, maybe.

In about 30 days, we'll have plenty to work with.

[gerard]

hello

Sorry Gentlemen but what is a lansaloy ?
And what do you look for ? A special type of glue ?
if yes I may help you !

gerard

[Mr. Widget]

It is the foam material JBL used from the late 50's through the mid 70's as a surround material. Originally it was an off white. With age it darkens to a tan color and stiffens. An application of DOT-3 brake fluid will soften it and return it to a state that is similar to new as long as the surround hasn't been cracked by trying to operate the driver while the foam is stiff.

Widget

[boputnam]

Widget, Ms. Gadet - and you... - take beautiful pictures!!

Hey, Oldmics

In a vacuum of real compositional knowledge, I'd be tempted to treat with DOT3 to the extent you can, and then carefully mend the splits with Household Goop, or other rubber-type cement that stays pliable.

I worry that any attempt at using a Lans-a-loy solvents could end in a disaster of unstructured goo, where the original surround shape gets lost and cannot be recovered.

[Mr. Widget]

Widget, Ms. Gadet - and you... - take beautiful pictures!!

Thanks... I took them awhile back when I was eBaying off my LE15A collection.

Bo...you should keep to the Front of House!

DO NOT USE CONTACT ADHESIVE ON YOUR LANS-A-LOY!!!!

"I worry that any attempt at using a Lans-a-loy solvents could end in a disaster of unstructured goo, where the original surround shape gets lost and cannot be recovered. :"

I'll second that.

Widget

[boputnam]

DO NOT USE CONTACT ADHESIVE ON YOUR LANS-A-LOY!!!!

Yea, well it ain't really like contact adhesive - it's more of a robust rubber cement. Bonds not-too-fast. I've used it in situations where it lasts for years and remains very pliable, and is completely airtight.

Anyway, what the hell is the polarity??

[4313B]

I'd be tempted to treat with DOT3 to the extent you can

Oh God! Not you too!

Oh what am I saying! I too would dump brake fluid on other people's JBL's.