Cleaning out old light seals

clingfilm · Feb 20, 2017

I'm just getting around to replacing all the light seals in my RB67 and I'm just at the stage of cleaning the traps. I'm using isopropyl alcohol but not all of the gunk is coming off? I've scraped quite hard with a bamboo chopstick but there's still a tiny layer of residue left.

Should I use something else to get this off or is it fine to leave on?

(The image at the top is of the residue)

anfenglin · Feb 20, 2017

I'd leave it on, it's not flaking off and the slightly rough surfaces makes a good base for the new seals to glue on.
My guess is that here the deteriorating old seals roughened the layer of paint up a bit, i've seen a similar thing in prisms of Mamiya M645s, the slimy and gummy foam ate up the silvered surface of the prism.

tedr1 · Feb 20, 2017

Isopropyl alcohol is good because it is mild and plastic safe. There are two stronger solvents that will remove any adhesive residue however plastic-safety is reduced. Naptha is available as lighter fluid and is an excellent mild solvent. Acetone is stronger however it is generally not plastic safe, when used with care it is a great cleaning agent.

mgb74 · Feb 20, 2017

I've seen (in typical stores) isopropyl alcohol sold in 50%, 70%, 91%, and 99% strengths (70% is most common). If you were using 50 or 70%, you might try a more concentrated version.

mdarnton · Feb 20, 2017

Around my violin shop I use odorless paint thinner for that type of thing. It's very low in terms of solvent strength, but is good with adhesives, waxes, etc--the kind of things we don't think of as permanent--while it doesn't attack paint, varnishes, etc. It would probably be OK on most plastics, too, but the thing always to do is run a spot check on a hidden spot with a little on a q-tip, first, to see if that does anything bad. If not, then you're good to go.

Alcohol is not the best solvent for this. Solvents have two variables at least: their strength, and specificity in what they'll attack. Alcohol is both relatively strong, and not really suited for adhesives, which is why it won't attack plastics, which are somewhat similar.

However, in this case, it's probably OK to take a stiff piece of plastic and use it as a scraper to get off what is get-offable off, and call it a day. I mean something like the sharp edge of a credit card. . .

canvassy · Feb 21, 2017

tedr1 said:
Naptha is available as lighter fluid and is an excellent mild solvent.

Naptha is what I use for taking off old seals, it works quite well.

pentaxpete · Feb 21, 2017

I've tried several times to buy 'Isopropyl Alcohol' here in Brentwood, Essex ( England) and no pharmacy stocks it -- I was told they need a 'special licence' so i use Lighter Fuel.

tedr1 · Feb 21, 2017

Yes perhaps it is restricted in retail environments for some safety reason. Over here it is a first aid item for cleaning the skin around a wound, quite harmless (although flammable).

This industrial supplier seems to have some but seems to be out of stock right now http://uk.rs-online.com/web/p/precision-cleaners-degreasers/0567890A/

EdColorado · Feb 21, 2017

I keep a can of white gas, otherwise known as Colman fuel, for repairs. It's a form of naphtha and works quite well on adhesives and doesn't harm plastics or most paint.

Pentode · Feb 21, 2017

Naphtha is what I would reach for.

Also, once you're down to that last bit of residue, the alcohol may be evaporating before it has a chance to soften the dried adhesive. You may try taking an alcohol-soaked Q-Tip (or cotton swab, for the generic) and resting it on a spot of adhesive for a minute or so and then trying the bamboo "scraper" again. The swab will stay wet for a while and may allow the glue to soften up some.

Lastly, +1 on using old credit cards to make custom scrapers for this type of thing.

LimeyKeith · Feb 22, 2017

pentaxpete said:
I've tried several times to buy 'Isopropyl Alcohol' here in Brentwood, Essex ( England) and no pharmacy stocks it -- I was told they need a 'special licence' so i use Lighter Fuel.

This is where I got my last bottle a couple of days ago: https://www.amazon.co.uk/dp/B00WL8NHEA/ref=pe_385721_37986871_TE_item

tokam · Mar 4, 2017

+1 for naptha / lighter fuid / white spirit / Coleman fuel. I find it far better than IPA which I use for other cleaning jobs. I also found naptha the best solvent for removing the degraded rubber coating on a Minolta Dynax 7 AF camera. It won't affect the plastic underneath.

DON'T use Acetone. Generally it is not plastic friendly.

Michael W · Mar 5, 2017

pentaxpete said:
I've tried several times to buy 'Isopropyl Alcohol' here in Brentwood, Essex ( England) and no pharmacy stocks it -- I was told they need a 'special licence' so i use Lighter Fuel.

I tried to buy it in Sydney a few years back and got the third degree at a pharmacy - apparently it's popular with drug users to clean needles. So i bought some on ebay from a place that did body piercing supplies.

klownshed · Mar 5, 2017

Isopropyl is also what I use. When the wooden scraper can't get the last bits, a cotton bud usually gets the last of the goop.

I get isopropyl from RS in the U.K. Maplins also supply it as it's used to clean electronic components.

tokam · Mar 6, 2017

Michael W said:
I tried to buy it in Sydney a few years back and got the third degree at a pharmacy - apparently it's popular with drug users to clean needles. So i bought some on ebay from a place that did body piercing supplies.

Michael,

Bunnings, (big home hardware store over here), will sell you IPA, Naptha (Maybe called shellite), acetone, MEK, turps, kerosene and methylated spirits by the litre or larger container. No problems with getting solvents in Sydney.

I buy syringes and drawing up needles from pharmacies for mixing up HC-110. Haven't bought a syringe in 3 or 4 years but I have a selection of 5 ml, 10ml and 20ml devices.

RalphLambrecht · Mar 6, 2017

pentaxpete said:
I've tried several times to buy 'Isopropyl Alcohol' here in Brentwood, Essex ( England) and no pharmacy stocks it -- I was told they need a 'special licence' so i use Lighter Fuel.

have you tried Boots?

klownshed · Mar 6, 2017

RalphLambrecht said:
have you tried Boots?

Boots don't stock Isopropyl.

The best place to get it in the UK for a consumer (i.e. not business to business) is from Maplin. If you don't have one nearby you can buy online. They sell it as an electronic cleaning solvent. It used to be sold as a tape head and vinyl record cleaner.

Buying it as an electronic cleaner ensures you're getting something that leaves virtually no residue and is relatively safe to use. Lighter fluid is not so residue-free and can leave oily residue.

Isopropyl can be diluted in water, which is sensible for testing to make sure you're not cleaning more than the gunk away. Use it as dilute as you can to get the job done. Used neat it's good for soaking cogs and gears. If it's good enough to soak a PCB in...

http://www.maplin.co.uk/p/isopropyl-alcohol-1-litre-re71n

TheRook · Mar 6, 2017

That little bit? I'd leave it on. Soon enough it will be covered by a new layer of light seal. As long as the remnants of the previous seal don't cause unevenness in the new seal, it won't be an issue.

benjiboy · Apr 24, 2017

THis stuff is magic https://www.amazon.com/Goo-Gone-Sur...qid=1493063794&sr=8-4&keywords=goo+gone+wipes and doesn't smell bad.

Patrick Robert James · Apr 24, 2017

Goo gone like Benjiboy linked to will work. Personally I would use Acetone as long as there are no plastics and it doesn't affect the paint. Test it. Goo Gone can affect paint as well, so test it.

When I replace seals, I make sure the surface is perfectly clean. If you are going to do it, do it right!

paul ron · Apr 24, 2017

EdColorado said:
I keep a can of white gas, otherwise known as Colman fuel, for repairs. It's a form of naphtha and works quite well on adhesives and doesn't harm plastics or most paint.

thats the stuff!

Tim Stapp · Apr 24, 2017

Not much experience with removing seals, but for alcohol, you may try looking for shellac thinner.

paul ron · Apr 24, 2017

home depot paint section... denatured alcohol quart can.

benjiboy · Apr 25, 2017

A much less messy way is to use the medical wipes that they useremove the gunk left by plasters in hospitals on human skin, just wrap one around a Q Tip and run it along the grooves.

dmr · Apr 25, 2017

I've never heard of isopropyl alcohol being restricted anywhere. I mean it's not a prime substance for abuse and it's far less flammable than gasoline.

Having said that, I learned that the worst part of changing light seals is getting the old grody ones out. Most important thing you need is patience. Personally, I would remove all of the residue from the old seals in order to give the new ones as clean of a gripping surface as possible. I've used acetone and it works well but as was said, it attacks some plastics.

Cleaning out old light seals

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