Rust question
 

Is rust progressive? I.e once it has begun does it continue to spread and damage metal, even if it is no longer in the environment that caused the rust originally?

Apologies if this is a dumb question, I couldn’t find the answer by searching. I have a chassis that has a little bit of rust on it, along with some transformer frames and laminations. I wouldn’t say it was serious or deep, the set works and I’m not fussed on the visuals as it will be hidden away.

But I wondered if I should do anything preventative before putting it back in the cabinet, I.e to stop it getting worse.

It was stored in a damp environment for many years but is now in a dry heated home.

Re: Rust question
 

I've personally never had it spread. I can't see how it would if it's in a warm and dry environment as any remaining moisture would've been driven out after several days? Though once there's rust, if untreated it's much easier for it to spread if given the chance to

'77

Re: Rust question
 

No, it won’t spread. It needs both oxygen (air) and water (liquid or vapour) to create the various iron oxides. Keep it dry as in low humidity, non-condensing and it will go into suspended animation !

Re: Rust question
 

Agree with posts 2 and 3. The critical thing with rust is it's porous nature- this as we know, is the reason even a small amount can't be sealed under fresh paint, carrying as it does it's own temporary supply of oxygen and water.

Dave

Re: Rust question
 

I notice that one the various repair and restoration shows which seem currently popular on TV that they very often leave things rusty, believing that this gives them character or a period feel.

However, one show decided to go down the route of applying some wax on a cloth, which may have dislodged any loose rust, but left a rusty surface. They felt that this improved the appearance and was an additional measure to deter further rusting, but I realise for that this may not be something you feel worthwhile in this case.

The only other issue that might be worth thinking about is whether the existing rust might shed any particles which might find their way in to some place where they do no good?

Of course, this could be a case of "if it ain't bust, don't fix it". I think I could be a "rustophobe"?

B

Re: Rust question
 

I can't see any justification for retaining rust to give something 'character' - wear and tear of in-service use is one thing, rust is usually caused by neglect and bad storage after something has fallen out of use.

Andy

Re: Rust question
 

Great news, I can enjoy it in it’s rusty goodness :D

I’d suspected the rust would cease once it was in a dry environment. Strangely after all the kit I’ve been mucking about with over the years, this is the first significant bit of rust I’ve encountered, most chassis’ I work on are perfect

The worst part was the rear socket panel (HMV 501), it had very deep rust and no paint on it. I removed 99% of the rust with a wire brush drill attachment, then sprayed it white.

Re: Rust question
 

I once got hold of a 1930s wall phone which had lived in a very wet environment. The chassis was thick with rust.

I removed the components, attacked it with a wire brush in an electric drill to remove the loose and friable stuff, cleaned it off with white spirit to leave a smoothish rusty surface (rather than bare metal), then sprayed with Hammerite smooth finish direct-to-metal paint. It looks fine and has been entirely stable.

Nick.

Re: Rust question
 

Another method not mentioned yet would be one of the commercial Phosphoric acid based rust treatments. They also form a phosphate layer which protects the surface from further rusting. I guess it depends a lot on whether the part is to be visible, or will be covered or painted in some way.

Alan

Re: Rust question
 

My experience has been that radios stored indoors don't rust unless they get damp for some reason, for example in a steamy kitchen or laundry room. If a rusty radio is brought into a dry environment no further rusting takes place once it's dried out.

Radios kept in a damp shed or garage will eventually rust even though steel parts may have been plated or painted from new.

Re: Rust question
 

Phosphoric acid is ideal for small steel parts that can be thoroughly de-rusted then immersed- but as a brush on jelly for (pitted) steel panels it promises what it can't deliver unless all the rust is completely removed from those nasty deep pits- not easy unless they are mechanically ground out. (Of course these days we have the Dremel..)

Dave

Re: Rust question
 

I use 36% hydrochloric acid for de-rusting. Sounds drastic but very effective. Then dry thoroughly and spray with 3 in 1 or any proprietary anti-rust coating. Strangely HCL acid seems to escape by some form of osmosis, even from thoroughly sealed bottles and tools,etc left in the vicinity which will rust rapidly. I know this sounds weird BUT I was plagued by corrosion in my workshop for years and tried everything;de-humidifiers, better ventilation,constant temperature above 18 degrees Centigrade, etc. Eventually I removed the sealed HCL bottles outside after leaving one over 3 foot distance from some immaculate brand new chisels and chrome vanadium coated spanners which heaviy corroded after 4-5 days!

Re: Rust question
 

This was kept in a garage for 30 years, and to be honest I’m not sure how well Sheltered that garage was. In bottom of the case It was full of dead insects, bits of leaf and sycamore seeds. It survived very well considering. Some delamination of ply and veneer here and there, but mostly in unseen places. All glued back down no problem. And no woodworm thankfully!

Re: Rust question
 

Post No.12- I have experienced the same effect with Hydrochloric (Muriatic?) Acid.
The polythene bottle started to suffer little blisters, and a steel table leg nearby became heavily rusted. No puddles or obvious leakage, but it was still evidently producing vapour.

It's a brilliant immersion de-ruster (although i add it to water to bring it down to around 16%,it works out more economic, slower and safer.)
Ideally it would be stored in a glass bottle with a tough HDPE jacket (but i doubt such a bottle exists!) Needless to say it eats Aluminium for breakfast.

Dave

Re: Rust question
 

Hydrochloric acid is essentially just Hydrogen Chloride (HCl), which is a gas at room temperature, dissolved in water. I would assume the plastic bottles it was stored in were to some extent porous to HCl, or had become so through degradation over the years.

We used to keep most strong acids in glass bottles, which were then indeed kept inside wide-mouthed, screw top, plastic containers, themselves stood in large spill trays, in a dedicated chemical storage cupboard...

Alan

Re: Rust question
 

Before we get too carried away, this is where we came in.

Re: Rust question
 

I always clean off loose rust and finish off with a light bicycle oil, not WD40 as it goes sticky although this was originally designed for this purpose. If it's rusting then the original plating has has been sacrificed.

Re: Rust question
 

Unless you want to get into more detailed and involved treatments that take lots of time and the removal of parts etc, a quick fix is to remove the surface rust using a scotch pad (green washing up pad), then wipe the area with a cloth soaked in WD40 to blend it in. It will then take on more of black appearance than 'rust', and it won't rust again if kept indoors at normal temperature and humidity.

Edit, just noticed that PJL has posted a similar procedure above.

Re: Rust question
 

If you're storing radios/parts in an environment where there's a possible risk of future rust, it could be worth looking at "Vapor phase Corrosion Inhibitor" products - you've probably come across these in the form of brown, slightly-waxy-textured paper used in packaging for drills, bearings, knives etc.

https://en.wikipedia.org/wiki/Volati...sion_inhibitor

Wrap your metal 'thing' in VCI paper, then over-wrap with cling-film! They didn't have cling-film during WWII but I've unwrapped several bits of 1940s US Military gear that's been protected by VCI paper and it's been in spectacularly-good condition.

Re: Rust question
 

I remember a rust treatment that when applied to rust would turn a slightly blue in colour.
John