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kef 104/2 B110 COATING

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bradspit1

Active Member
Hello everyone! ive just managed to land myself a pair of 104/2 for a good price but in need of some tlc. in particular the mid drivers coating is peeling / delaminating. from some googling and reading this is a pva type of coating i believe? ive seen speaker repair sites selling bottles of redoping glue and wondered if i could remove the remaining coating with tweezers and redo the coating? i know the coating serves a purpose so its not a purely cosmetic exercise and im never going to get them to factory condition but im thinking a single layer of the coating would protect them without hopefully affecting the sound of the driver? im also replacing the tweeters as one is dead and have gone for the vifa DX25TG from wilmslow audio which seem to be a good match according to neil from wilmslow. they are 4ohm and 93db which is close to the T33 spec i think. i am also doing the inner foam doughnuts on the B200 drivers and luckily mine are an earlier 2 post pair ( matched a-b) so have the rubber outer rings which is a bonus. finally the cabinets need some attention and have deep scratches and im thinking to sand them back and maybe oil them with danish oil or similar? has any one done cabinet work and can recommend what grade of sandpaper or wire wool to use? ive heard 000 gauge wire wool mentioned before. any feedback would be gratefully recieved as im in love with the sound of these speakers even with a tweeter out! thanks for looking brad.
 
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The drivers were a Bextrene (styrene-butadiene copolymer) cone damped with a Plastiflex PVA (polyvinylacetate) coating. I don't know if you could find Plastiflex today.
 
thanks for the reply Lou. i guessed the exact coating they used might not be available but wondered if something like this would work : https://speakerrepairshop.nl/index....c&action=article&group_id=18&aid=5333&lang=en. i was thinking 1 coat only just for protection as the original coating has flaked badly and looks unsightly and wont be giving much protection now id imagine. my thinking is one layer would hopefully have minimum impact to the sound compared to putting down 3 or 4 layers which im guessing would.
 
The Plastiflex coating was not applied for protection but to achieve the proper damping of the speaker cone. It has an effect on the sound, even the thickness affected the sound. The coating you reference is a silicone based coating and IMO would change the sound of the speaker. Also that silicone coating is designed for paper cones and might not adhere to the Bextrene cone of the 104/2. I would try to find a source for Plastiflex or something similar (polyvinyl acetate in a suitable solvent).
 
thanks again Lou. so even the fact it is peeling off badly has probably altered the sound already. hmmm where to find a similar product though? time to get googling i suppose unless someone else can pitch in with a product they found or have already tried this?
 
I am not sure that the Plastiflex in your link is the same formulation as KEF used.

Anyway, I was researching my notes on the coating KEF used and came across a statement that said the coating on the back of the cone (several coats) did the real damping and the coating on the front (single coat) was only used to make the central dust cap stick and be airtight. The coating on the back did the real damping and was controlled by weighing the coated cone.

So maybe you don"t need the front coating.
 
Lou thats fantastic info and just the type of info i,d hoped someone had access to or could recollect. i guess i just leave well alone then. it does look unsightly seeing the peeling to the cones but i guess the sound is the most important consideration. thanks very much for your input im very grateful. the stuff in the link was the nearest that ebay had to offer and im sure wasnt the stuff Kef used lol.
 
If you really want to coat the front cones, something similar to the KEF formulation is actually Elmer's White School Glue. The Borden Co (they started Elmer's Glue) actually supplied KEF the Plastiflex coating for their Bextrene speaker cones. The glue would have to be thinned down with water and best applied by spraying on to get an even coat.
 
Lou thanks again for your input. i will check out Elmer,s glue for sure as i,d like to tidy them up without affecting the sound if i could. ok google here i come lol.
 
Yes Elmer's white school glue. It dries clear. I have used it as a spray diluted down (about 4 to 1) with water for model railroading applications. You have to play around with it to get it to the right consistency to spray properly. Any spray bottle works. if you did decide to use it, i would try it first on some practice pieces to get the coating right so you don't overdo it.

People also use it less diluted for decoupage and apply it with some type of foam brush. That could work also for your speakers.

You can read up about these applications.

My only concern is whether it will stick to the Bextrene cone.
 
thanks for confirming that Lou. the store that stocks it is 5 mins away from my house so thats a bonus. will buy some for sure and will wait until the refurb of the cabinets and refoaming of the center doughnuts of the b200,s has been done before i decide to proceed. you,ve been a great help with your advice Lou, many thanks.
 
just for info if anyone is planning on refurbing your speaker cabinets if they are in poor shape, try howard restore a finish first! this stuff is superb! i was about to start the long process of sanding back and re finishing the 104/2 cabinets but heard about this stuff and gave it a try and they came up great. dont get me wrong its not showroom finish and some scratches are still visible but kind of filled in to look better. perfectionists may not feel its good enough but im very happy with the finish. now its time to remove the b200,s to redo the inner doughnuts!
 
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