"Treating Lead Rot?" Topic

I have a handful of old Star Frontiers ships with a touch of early lead rot, and one with a more advanced case. Per the George R.R. Martin blog post quoted here: TMP link there is a treatment that can be done. Good turpentine can be found, but I'm a bit lost on the other ingredient, as "mineral oil" covers a lot of ground, and "highly refined medicinal mineral oil" is a new one to me.

Does anyone have a source or some guidance on reading the secrets behind the often terrible labeling of retail chemicals?

Drug stores usually sell mineral oil, or at least they used to.

Might have to try that.

Have some of the old Asgard minis that are 'infected.' Some quite bad.

Also some Minifigs.

Curious as to how that might affect paint though.

Guys,

What is lead rot?

Dan

Oxidation of the metals containing lead used in figures, esp ones made in 70's.

So modern casts should be ok?

Dan

Generally. Even the modern casters still using lead are not using the mixes that rot anymore, and the pewter that most use has little to no lead.

Here's the one that's bad, the Star Frontiers Terran Freighter. Untouched on the left, badly rotted on the right.

Likely a loss, or a wreck model.

Okay,

I am a former museum curator, which means I have a basic knowledge of preservation problems, but not a professional background in chemistry like a museum conservator. Apart from health issues, lead in itself is not the problem. There are lead objects found in archaeological contexts that are centuries or millenia old, so lead does not inevitably develop "lead disease," But impurities in a lead casting, such as acids and salts can make some particular objects more prone to oxidation than others. And the environment surrounding the lead also plays a big role. Direct contact with acids or acidic vapors in the air, salt, high humidity, and high temperature are all negative factors, made worse in combination with each other.

Raw wood is acidic, and so is paper that has not been treated to de-acidify it. Therefore, unfinished lead objects should not be stored in direct contact with unfinished wood or cardboard boxes. Some forms of plastic are pretty neutral in Ph and chemically stable, others not good at all. Avoid any that have a strong smell because that means they are giving off vapors that may produce undesirable chemical reactions.

Ideally, lead miniatures should be thoroughly cleaned, then primed when new to prevent problems developing. The cleaning is to remove any oily residue from compounds applied to the molds to facilitate release of the miniature after casting. Any oil or dirt on the surface may prevent proper adhesion of the primer. Note that a primer is not the same as a base coat of paint. A proper metal primer contains pigment just so you can tell that that you have completely covered the surface, but it is formulated specifically to adhere well to a metal surface, thoroughly seal the surface, while not containing anything that will react negatively with the metal. Various types of paint, by contrast, may offer poor adhesion or sealing, since they are made simply to cover the surface with pigment, and a few may actually be harmful to the surface. Floquil model railroad paints had metal primer in small bottles. I think the old Polly S line of paints did too, but I'm not sure what is currently available on the market (I stocked up years ago and haven't quite exhausted my old supply yet).

Now, down to the specific problem of the original post. If you really want to expend the effort to try to save these miniatures, I would try this. First, get rid of the loose corrosion with a soft brush (an old toothbrush would work). Then give them a soak in undiluted household ammonia for a few hours in a clean glass container. Ammonia is alkaline and will neutralize any acids, as well as degrease the surface. Note that ammonia will not harm metal, but is very destructive to many other materials, including most paints, so do not try this on painted miniatures. After this step avoid touching the surface with bare fingers, which will leave traces of salt and body oil; use tweezers or wear rubber or plastic gloves. Next, give a thorough rinse in distilled water (you don't want any remaining ammonia to react with primer or paint), followed by a quick one in a fast-drying solvent such as denatured alcohol or acetone. Then, as soon as the surface is completely dry, proceed to apply the metal primer. Personally, I think that brushing it on is more likely to penetrate to all the little hollows and undersides than spraying. Make sure the primer has dried for a couple of days before applying any actual paint.

Good luck!

In addition to what attilathepun47 said, I usually throw one or two desiccant packets into each of my figure boxes. I have pretty much gotten rid of all cardboard storage and moved to Really Useful plastic boxes. You get this little desiccant packets in all kinds of stuff, so the family knows to put them in my painting room.

Mineral oil should be found at a hardware store ( used for cutting boards and other food handleing wood) or drug store ( as it can be used internally for ailments)

Good cath Surdu. I meant to mention the silica gel dessicant, but forgot to. It is a really good idea for anyone with a collection in a humid environment. The gel eventually absorbs all the moisture it can hold, but it can be recycled by heating it to a temperature high enough to evaporate the water contained in the gel.

That ammonia sounds worth trying.

That and acetone – problem I had in the past with alcohol was that there was enough water in it to restart some corrosion.

Given that some plastics such as Tupperware are apparently not good, what about cardboard boxes painted with enamel paint or spirit based wood varnish? The paint/ varnish does absorb right into the cardboard and strengthens it – I have quite a few figs in such. A good idea or not??

Cardboard that has been sealed with paint or varnish should be fine. Most plastic storage boxes should be okay too, but don't use the ones that have an airtight seal. That can trap atmospheric moisture inside, which may then condense out to liquid on the surface of the miniatures when the temperature falls. Warm air can hold a lot more water vapor than cold air.

I believe a lot of the foam inserts in a lot of old lead minis causes the lead rot. I had some of the old Target games Chronopia miniatures. All of them had lead rot and in every case where the foam inserts were touching the lead, the rot was significantly worse, the pattern of the foam was actually etched into the surface. In many cases the sides away from the foam didn't have any rot. I'm guessing the foam was breaking down and releasing some chemical that accelerated the corrosion. As they were so bad, I decided to take them out of the boxes and threw out the foam so that they could air out and test my theory. I've left them out of the boxes since then. This was four or five years ago and the lead rot hasn't gotten noticeably worse. So get rid of those foam inserts in your old lead miniatures. They were meant to protect them, but they are actually doing harm.

Thanks for the response on cardboard varnishing Attila. This gives a way forward.