Hasselblad A12 back - 'Brushing up' light seal?

Twotone · Apr 23, 2023

Hi folks,

I've got a few A12 backs for my 500C/M that need the light trap seals changing.

This consists of the foam strip that sits within a folded bit of 'foil' which is some sort of plastic and then a separate 'woven' seal that sits in a groove on the rear of the 'face plate'.

I've got a few kits coming which include both seals, but after speaking to a few different Hasselblad technicians, I've established that the thin 'woven' seal doesn't always need changing as often and can be 'brushed up'.

Before I get a stiff bristled brush and persuade the seal to 'stand up', is anyone aware of the appropriate method beyond what I'm suggesting?

Thanks,
TT

Axelwik · Apr 23, 2023

Wasted film and time is more valuable than a few dollars in parts, but the only parts I ever change are the plastic/foil piece and foam. And the parts from Hasselblad are just as cheap as the aftermarket.

While you're waiting you can put a piece of black electrical tape over the darkslide slot to prevent light leaks, and just leave it on. The darkslide doesn't need to be inserted to change film - can be done right on the camera without removing the back. I see so many newbies taking the back off to change film - it's a lot easier to fumble around with two things rather than three (four when you count the film)!

Pieter12 · Apr 23, 2023

Alex Varas · Apr 24, 2023

I think their assumption is correct. For me if looking at the front plate horizontally I can see the seal coming up a bit, no need to change it. Brushing up works fine as it works in older light seals in cut plate holder.

Twotone · Apr 24, 2023

Alex Varas said:
I think their assumption is correct. For me if looking at the front plate horizontally I can see the seal coming up a bit, no need to change it. Brushing up works fine as it works in older light seals in cut plate holder.

Thanks for this - is there any particular method or brush type suggested?

Twotone · Apr 24, 2023

Axelwik said:
Wasted film and time is more valuable than a few dollars in parts, but the only parts I ever change are the plastic/foil piece and foam. And the parts from Hasselblad are just as cheap as the aftermarket.

While you're waiting you can put a piece of black electrical tape over the darkslide slot to prevent light leaks, and just leave it on. The darkslide doesn't need to be inserted to change film - can be done right on the camera without removing the back. I see so many newbies taking the back off to change film - it's a lot easier to fumble around with two things rather than three (four when you count the film)!

I absolutely agree, I wouldn't cheap out for the sake of it!

Thanks for the suggestion.

mshchem · Apr 24, 2023

You need to change the foam in the seal. To do this you need to disassemble. If the flexible plastic is still good I suppose you could find foam??

Brushing just gets rid of the powdered dried out foam, doesn't solve the light leak.

Easy and fast, load film, install back, pull dark slide, cover slot with a couple layers of black electrical tape.

I would just replace the seals. I'm a bit shaky and I can do it.

mshchem · Apr 24, 2023

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Twotone · Apr 24, 2023

mshchem said:
You need to change the foam in the seal. To do this you need to disassemble. If the flexible plastic is still good I suppose you could find foam??

Brushing just gets rid of the powdered dried out foam, doesn't solve the light leak.

Easy and fast, load film, install back, pull dark slide, cover slot with a couple layers of black electrical tape.

I would just replace the seals. I'm a bit shaky and I can do it.

Hi there,

I'm not talking about the flexible plastic or the foam seal, I'm talking the separate thin woven seal.

Im happy to change it, but the reason for this thread is because two different ex-Hasselblad technicians have informed me it doesn't need changing each time the foam seal is changed, and can instead be 'brushed up'.

The purpose of my post was to understand the particular method in which people use to brush it up but I'm just going to have a go and see.

Thanks

mshchem · Apr 24, 2023

Twotone said:
Hi there,

I'm not talking about the flexible plastic or the foam seal, I'm talking the separate thin woven seal.

Im happy to change it, but the reason for this thread is because two different ex-Hasselblad technicians have informed me it doesn't need changing each time the foam seal is changed, and can instead be 'brushed up'.

The purpose of my post was to understand the particular method in which people use to brush it up but I'm just going to have a go and see.

Thanks

Got it! I would start with a stiff toothbrush. I've not had problems with, what I call "felt" seals, at least not that I know of. I have a couple small brass brushes that could maybe work.

Now that I know what you are doing, I'm going to be checking my A-12 magazines

itsdoable · Apr 24, 2023

The velvet strip does not need to be replaced unless it looks bald. Most aftermarket kits (like the one listed above) do not come with the velvet strip, Hasselblad OE kits do.

The Hasselblad OE seals use a metal foil instead of plastic. The metal foils last forever (unless you accidentally fold/wrinkle them) and you can just scrape the old foam off, and cut some replacement foam for them. It's the foam that deteriorates. But the aftermarket plastic kits work fine and are inexpensive.

Hasselblad A12 back - 'Brushing up' light seal?

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