Zinkpest ? for Frank H !

[keifer kahn]

Its been very informative angus,fantastic info.
All of my zink pest beasties have totally different types of zink pest characteristics.
The F&R tank badge has deep pits of corrosionwith zinkpest evident in the base of each pit .The zinkpest in this case ,is the light gray type.Like a mushroom colour .These pits& holes in some cases have eventually linked up together to form entire patches of zinkpest.Also what is evident are beads of silver left behind that could not be absorbed by the base zinc.
One of the gound dug IABS which is an FLL type,has the hard crystallized white form,and under magnification looks like large salt granules.It also has bubbling ,where the top finish has stayed intact,and the zinkpest has infested the metal underneath.Just like rust under paint.
The other badges i have,also have similar characteristics but none of them are exactly the same,
Its been a fascinating thread,This info has been greatly appreciated.
I assume from this thread,that some people like ground dug stuff,
I wonder if it possible to have a Ground dug forum to go along with the rest of the award,headgear,etc etc forums.
Thanks again for the info angus,i have found it excellent.Alot of answers to some questions ive had for a while.Excellent!

regards keifer

[anguspm]

Hi Skip,

I can't see a logical reason for zinc pest jumping from one badge to another unless they were touching (in the same way that a nut that rusts also contaminates the bolt). Corrosion can spread from metal to metal but only if it is touching. Keep a gap of a cm between each edge and you should be fine.

Whilst we talked about corrosion and how it forms we missed one of the ways to prevent it. We did mention sealing (paint, varnish etc) and removing moisture (de humidifying, dessicant) but forgot one concept which is "sacrificial protection".

Sacrificial protection: This is where you use a material that decays faster than that which you are trying to protect to draw the moisture away. This is most commonly found on ships. the steel hull of the ship will have a solid block of copper attached to it. The copper will decay/corrode taking the corrosive properties out of the water so protecting the steel. Within a case of badges or medals an iron nail in the bottom of the case would corrode but prevent the badges from corr****g. In many ways corrosion is like electricity in that it takes the path of least resistance.


ONE THING I FORGOT:

Cleaning zink pest away: Use alcohol sparingly only applying to affected areas by means of an artists paintbrush or cotton bud (those ear cleaner things). I am not yet up to speed on the materials used by the manufacturers to colour the badges and would recommend keeping the alcohol away from the wash where possible. I must admit to using it to clean dirt from a 1914 EK2 and it didn't upset the paintwork but like any solvent "try in a small area away from view before application".

If anyone needs more information or has a problem regarding corrosion and its prevention on pieces other than zinc then I'll try to help. A message on the forum or by PM is no problem for me.

Regards,

Angus

[don]

Thank you Anguspm.
The information on zink pest was great.

don

[skip]

Yep, I second that

[Tor]

Great information!

This tread is really helpful

[stogieman]

Excellent Thread!

I had mentioned in a thread a couple of years back about zinc being unstable and continuing to bond with free hydrogen in the atmosphere, but this thread has taken it to a much deeper and scientific level. Great information and well stated.
<p>
NOW Angus, help us out with the finish-issue??! WHY do zinc badges seem to "absorb" their gilding & silver washes??
<p>
If there were any way to stop that, it would make many a collector verry happy!

[MH184]

Rick,

I read you used to collect very old toys, I have several pre war Dinky Toys, have you ever heard of the the known measure to prevent metal splits and cracking in these early toys useing Linseed oil ! Could this aid in preventing badges from cracking I wonder..........Angus?????????

Kind regards,

Marcus

[James Noble]

I had mentioned in a thread a couple of years back about zinc being unstable and continuing to bond with free hydrogen in the atmosphere, but this thread has taken it to a much deeper and scientific level. Great information and well stated.
<p>
NOW Angus, help us out with the finish-issue??! WHY do zinc badges seem to "absorb" their gilding & silver washes??
<p>
If there were any way to stop that, it would make many a collector verry happy!

Rick, when you say gilding & silver washes are you referring to eletroplating or the use of metalic based paints?

[anguspm]

Hiya All,

Someone must have dredged this one up from history! At least someone knows how to use the "search" function!

Finish absorbtion on Zinc badges:

Ok for a start that title describes the exact opposite of what actually happens. We've all seen the Russian Front medals and the way the paint/finish starts bubbling. This is exactely what happens with the badges you mention only on a much finer scale.

Instead of the big flakes you are getting microscopic flakes being repelled/dislodged by the zinc all the time. Whilst to the naked eye it looks like the finish has been absorbed into the badge it has actually been "pushed" away. Because these badges weren't given a "primer" (sort of a paint equivalent of double sided sticky tape) to hold the paint to the badge the two chemically attack each other (like coke and pennys). This is why when the finish goes the zinc (badge structure) has a very small loss of detail. Similar to the grooves on a record changing from V to U.

Bad news There is nothing you can do to stop it. You cannot go in and put an adhesive between the metal and paint, its too late for that now. All you can do is make sure there are no catalysts around: moisture, scratches etc. Once the bare metal is exposed you could use a laquer to prevent zinkpest as described earlier.

Lubrication (Ooo err missus)

The point about linseed oil is a good one for dinky toys but probably not best for badges.

Basic principle: all metals expand and contract with changes in temp. By applying a penatritive oil the molecules in the metal are lubricated and can slide past one another easier. This is the same principle behind lightly oiling a gun barrel.

Why not badges: Determined by their individual manufactures the substances from which badges were struck, cast, stamped etc tend to be a mixture of low quality metals. The introduction of oil would probably do more harm than good. For example batch x of manufacturer y's IAB's contains 1% potassium. Not enough to see with the naked eye but upon the application of oil you'd soon see a whole new sort of zinkpest! Something akin to shaving foam would be near the mark! Secondly Badges do not crack due to drying out (lack of lubrication). With these badges its more brute force or metal fatigue (brittleness of metal increasing each time you stress it: known as work hardening).

I hope thats helped in some way?

regards,

Angus

[Eric Gaumann]

zinkpest, zink pest, zinc corrosion

Time to bring this one back...
....as a couple of my 3R tinnies are sprouting zink corrosion spots (here in the wonderful Florida humidity).
So should I give 'em a a good brushing (with nylon (or brass?) bristles) and then a vaseline coating? How about "mineral oil"? That's the stuff I use on kitchen cutting boards and knives.

[Darrell]

The residue of this is the fluffy white deposits you see on your badges (cant remember the chemical name for the deposit).

ZnO ? (zinc Oxide)

[Eric Gaumann]

ZnO ? (zinc Oxide)

If InO equals "rust" then ZnO is, indeed, "zink pest". Ie. crappy, ugly stuff that shouldn't be there and shows up unwanted and needs to go away.

[Darrell]

If InO equals "rust" then ZnO is, indeed, "zink pest". Ie. crappy, ugly stuff that shouldn't be there and shows up unwanted and needs to go away.

Well rust is Iron oxidizing to Ferric Oxide .... so I would guess this white substance is zinc oxidizing to Zinc Oxide

[anguspm]

Iron = Fe

FeO2 is rust

Eric,

Please DO NOT use a brass brush!!!! Spaerk plugs are different to tinnies

[burgerhaus]

Ok All,

Whilst not being an expert on badges and militaria and the problems inherrent I may be able to give a little background on "zinc pest" as its been called.

Background: I work in aviation engineering and there are two things an aircraft designer wants from a material: strength and minimal weight. Aluminiun/Zinc/Ceramics and Composites all have these attributes. It therefore follows that zinc is used in the casting of such components as gearbox casings.

Zinc corrosion: Zinc reacts to hydrogen by producing an endothermic (gives out heat) reaction. The residue of this is the fluffy white deposits you see on your badges (cant remember the chemical name for the deposit). This is in much the same way that Iron reacts to H2O to give rust.

Prevention: Zinc as a metal is fine if it is sealed from the atmosphere (paint/laquer etc) or kept in a humidity free environment.

Conclusion: For just about all of us it is impossible to build a "dry-room" or move house to death valley california (lowest humidity in the world?) so there has to be an alternative.

a) If you are one of those who likes to handle the badges on a regular basis then the application of vaseline will seal out the moisture from the badges surface. Just remember to check that the vaseline isn't drying out and letting the air and therefore humidity attack the badge. This is much the same as spraying the bottom of your car with oil before winter driving.

b) If you can get by without touching the badges put the into a frame or box that is sealed with a silica gel/ desicant pack. The desicant will remove the moisture from the atmosphere you've trapped. So preventing the decay.

NOTE: If your badge has its original paint remaining it will be sealed against the air and humidity so niether of these actions is necessary.

CAUTION: Using vaseline is a temporary measure that seals the badge. If removing it use alcohol (100% proof) as washing a badge in warm water introduces the agents that will attack the badge.

Hopefully I've managed to enlighten you guys as to how zinc corrosion happens in the same way that you have educated me with regard to badges and medals.

As a footnote to those who wish to wash zinc badges in water I have seen a helicopter gearbox pulled from the sea off Serbia that had been submerged for two days and all that remained were the titanium gear teeth!

Angus, I know I'm a litle late in this but do you mean 100% alchohol that we drink or something like rubbing alchohol? Thanks for your help. Robert