"PVA Basing and Lead Rot" Topic

I was scanning the pages here and noticed someone mention PVA would encourage if not assure lead rot. My questions are two fold, if in fact this is true, when do I need to schedule the funeral pyre for my recently based gladiators? What is a good substitue for PVA to attach sand/gravel etc. (This is for character figures, that I am quite proud of). I would prefer something with a high viscosity so as to avoid cappilary action. NO ZAP A GAP as I have found it to be stil to thin and unforgiving?

Hello,
I sifted through the boards but couldn't find any mention of lead rot caused by PVA. Which post said that?

I am a little surprised by this info. PVA is considered an archival adhesive. Obviously, I don't know about PVA and lead interaction, but am very interested!

I use a mixture of PVC and latex paint to flock figures and so forth. In all my years of painting I have never experienced lead rot.
Some people even glue the figures onto the bases with PVC, I find this difficult to do with 15's and not necessarily easy with 28's.

My question refered to "Displaying you Mini's and How? about 3-5 pages down. This by the way, is something that I had heard of a long time ago as well.

Thanks

John

Is Elmers a basicaly PVA?

PVA is used in my field of archaeology for a number of purposes in curating artifacts, for the reasons that it is reversable (you can, e.g. "unglue" what you glued together without damaging delicate pottery and the like) and it is fairly intert and stable over time. I can think of no good reason why PVA would react in any way with white metal alloys such as are used in casting miniatures, nor can I recall reading any such suggestion in the journals intended for curators, conservators or archaeologists.

PVA = Polyvinylacetate, and over time, may hydrolize to produce acetic acid. While not an issue with pottery, prolonged exposure may cause problems with lead. ( Acetic acid and Hydrochloric acid produced and emitted from new plastics/glues are known causes of lead rot ).

1) Sealed lead is more resistant

2) Store figs where there is sufficient airflow around them, so vapors are disappated. Put a vent with a small fan in your display case, or display them on open shelves.

-Daniel

PVA was listed as "potentially destructive" in the only serious study of lead rot I've ever seen, on the "curator of navy ship models" website, which can be found here:

link

The article is mostly concerned with the outgassing of acids by woods used in ship models and in old cabinet frames. The acidic gas becomes concentrated in a sealed glass cabinet and attacks the lead and other metals.

Page 5 lists other potential sources of acetic and formic acids, including PVA/"white" glue and polyurethane varnish (eg Future Floor Wax). Note that many other types of paints and varnishes are also listed as "potential" sources, including plastics in general.

The PVA I've used in archaeological labs is something different from common craft glues. The supposedly "pH-neutral" PVA used in archiving, book binding, etc is much more expensive then Elmers. To my knowledge Elmers makes no claims regarding pH over time.

PVA stands for "polyvinylacetate." Different kinds of PVA do give off acid over time, as shown in some tests (I'm guessing from the name that PVacetate is releasing acetic acid as it cures). Acid is what reacts with the surface of some lead compounds and converts them into something very different, just as the acid vapors leaking from your car battery can cover your terminal posts with a thick growth of crumbly salts.

We do need more testing and study in this area. Certain mixes of metal are more prone to rot than others, yet I know of no figure manufacturers who specifically claim to be aware of this and to be formulating their metal to avoid it. I do feel that most figures today probably are at less risk due to better formulation of metals, but we might not know for sure until several decades have passed.

The only examples of lead rot that I have personally seen have been on TSR branded figures from the early 1980s, in several different TSR figure lines like Gangbusters and Star Frontiers. These were sealed in blister packs or shrinkwrapped in cardboard boxes with foam liners to cushion the figures and were opened only recently, 20 years after being packaged. Many of the figures appeared to be covered with dark grey bumps all over, which actually extended deeper inside the figure below the surface. Cutting the rotten areas out with a knife required digging into the surface and leaving pock marks. The "rotten" lead was hard and gritty, feeling almost like embedded pieces of concrete, no longer soft and smooth like the surrounding lead.

(I consider all work on these figures to be a temporary investment. It's my understanding that the rot eventually can be self-sustaining, that rotten figures that are painted will release acids beneath the paint, which becomes concentrated and causes more rot in previously unaffected metal.)

I suspect that the early 80s TSR figures were unusually prone to rot due to their specific formulation of metal. They were then exposed to 20 years of increasingly concentrated acidic vapors from the deterioration of the foam package liner, the cardboard of the card back or box, and the plastic of the blister packs. This fits the pattern of bad conditions described in the navy model article cited above: lead trapped in an unventilated confined space with acid vapors.

I have seen many, many other figures of similar age or older still sealed in their packaging with no damage, including perfect-looking figures in blister packs that showed profound deterioration of the packaging itself: discolored and brittle plastic on the front of the blister packs, browned and brittle cardstock on the back, and crumbling foam liners inside. In some of these cases the acidic vapors may have failed to concentrate because the crumbling packages didn't remain sealed (the glue holding the blister to the card is often the first thing to go on an old pack). In most cases it seems certain that the lead mixtures of the surviving figures have proven themselves to be less reactive to acids.

I'll cut this 'short' but one other concern comes to mind:

Are any manufacturers of tightly sealed figure cases specifically promising that their case plastic and foam liners are acid-free over time?

ljumpajav, regarding an alternative to applying gravel to bases, I've never trusted PVA/white glue to hold long term so I've always used 5-minute epoxy spread over the base and sprinkled ballast onto it. It's worked great for me. To avoid a messy job and keep the glue off the model as much as possible, I use one of those flat hard-plastic coffee stirrers from McDonald's. I use an X-Acto knife to cut the blade end to be narrower and use it to mix the glue and spread on the base like a mini-spatula.

I haven't seen much lead rot with sealed figures from the early 80s. I buy them often on ebay. I have noticed some on loose figs I've bought and attribute it to how they were stored which I have no way of knowing how.

I have hundreds of figures I've painted in 81-83 and none show any signs of this.

Perhaps 20-30 years down the road something will happen like this but who cares, most of us will be too old to care.

Come on, you want those little guys to stay together so that alien archaeologists can discover you buried with your bodyguard ten thousand years from now. ;-)

Some of the chemistry mentioned so far in this thread is supsect. Just because PVA is polyvinyl acetate, it doesn't meean that it is outgassing acetic acid at any appreciable rate. (In theory, the aluminum your beer can is made of dissolves in your beer. But it is something like a trillionth of a trillionth of a trillionth of a gram per liter. Don't think its going to matter.)

The more likely culprit in lead rot is oxygen and ozone. High lead content alloys will corrode, in a chemical process similar to iron rusting. Sealing helps. Modern lead-free pewters, which I understand to be mostly tin, should be highly resistant to corrosion.

The chemistry comes from the article cited above, which is almost certainly the original source of the concern about PVA cited in the top post, and from other studies of PVA products conducted by and for archivists. All positively identify the release of acid (which is mostly of concern for the preservation of paper or other perishables).

I do agree that the amount of acid released from all our glues, paints, and varnishes combined is probably at negligible low levels. I would like to see a detailed analysis of which gasses can affect lead and in what concentrations. Even more useful would be a list of cases of lead rot in gaming miniatures correlated to the brand of figures and their storage methods.

What concerns me most is that confinement in an air-tight space has been identified as one of the most significant contributing factors leading to lead rot. In any type of sealed container the offending gas has a chance to build up and affect the metal over time. This leads me to believe that the foams and plastics in miniatures storage cases, gun cases, plus the cardboard boxes from boxed sets of figures, etc should be considered a serious potential source of trouble if certain high-lead content figures are placed inside and left for an extended time.

Jake, from an archivists perspective, what do you think about the durability of resin, soft plastic, and hard plastic figures? What sort of paints would hold up best over time (with and without light exposure)? Anyone have a longevity estimate for polymer clays?

I heard that "lead rot" is actually caused by poor alloys, usually too much lead. Over time the metals slowly separate.

I know some friends who used to work at a certain miniature manufacturer who witnessed the owner tossing lead into the melting pot to save money. Years later, those figures made with the adulterated alloy are slowly crumbling to dust.

Sealing them will do nothing. It is not a reaction to oxygen or glue. It is inherent in the metal.

That's what I've heard anyway, and what I've seen of the damage seems to support that theory.

Excellent thread.

Pre painting, is there a cure for lead rot? ie will it stop if I clean it off and then seal?

I have a small number of very old citidal figures that have lead rot (a built up white powder coating) is there a cure? These are figures that will never pass this way again. I'd like to save them if I could.

I'm not an archivist by specialization, nor a metallurgist, but as a generalist who worked with artifacts I learned a little about archiving and museum storage along the way. Mostly enough to know what might be a problem and when to ask for help. I've been posting what I do know or suspect, and hoping someone else can fill in more gaps.

I think more anecdotal evidence would be really useful here, given the wide variety of figure manufacturers using different ingredients and the different treatment we have all given our figures. I think Tony's observation about metal quality is particularly relevant. My TSR figures grew dark tumors in just 20 years (not the usual white powder described as 'lead rot'), while other figure types survive the same conditions longer unscathed. I suspect there may be some inclusions of unwanted material in my figures.

Just to calm some fears, there are lots of lead-containing toy soldiers from over 100 years ago that are still intact. Some of the worst problems with rot seem to be when those antiques with high lead content have been stored in tightly sealed wood and glass display cabinets.

I couldn't guess about resin figures, except to note that many different types of plastic have been called resin, and there's probably a varying range of durability.

Plastics in general are not very durable over time compared to other materials. Many types will continue to exude plasticizers for many years (the chemicals that keep them 'plastic') until they become brittle. In the process the escaping volatile chemicals can destroy other paper or plastic items in close proximity. 1 plastic item touching another in storage may exhibit surface crazing spreading from the point of contact. Plastic in cheaper photo albums will strip the colors right off the photos.

The 'hard' polystyrenes used in plastic models and many of the plastic figures used in gaming seem to hold up reasonably well over many decades, judging from the reasonably good condition of old plastic models that haven't been abused. They probably are slightly more brittle, but they aren't disintegrating.

I would have to guess that soft plastics, which presumably contain more of the volatile chemicals that keep them soft, might exhibit the most changes over time as they become brittle. They might need extra care in handling after many years.

Well you could always try tasting the lead rot spots. If they're caused by acetic acid (vinegar), then they will be 'sugar of lead.' This stuff's the reason that we got rid of lead seals on wine bottles. It tastes good, but it's bad. I've got some early 80's TSR minis (D&D) still sealed that are suffering from lead rot. I think that one of the reasons that no one seams to know what's going on is that there are a myriad of conditions being described as lead rot. One of the better explanations I read involved the minis cooling at different rates in different parts during casting which results in different crystal structures in different parts of the metal. So, years later, some parts are vulnerable, while others are not.

I've recently discovered some black spots on some of my unpainted minis.
Is this considered a form of lead rot?