Beyond The Sprues

Modelling => Tips, Tools & Techniques => Topic started by: Frank3k on September 21, 2020, 04:45:52 AM

Title: Don't mix lead and cyanoacrylate (Superglue)
Post by: Frank3k on September 21, 2020, 04:45:52 AM
You learn something new every day.
Not only should you avoid lead exposure (or wear gloves/respirator unless you really want to be a Roman or an inner city child) you don't want to mix lead and CA glue (http://www.ratomodeling.com.br/articles/lead_ca/lead_ca.html) The lead will react with the glue and start expanding, leading to cracks. The link has horrible NSFH (not safe for hobby) pictures.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: ChernayaAkula on September 21, 2020, 07:30:20 AM
Has anyone else had this happen to them? Whenever people are cautioned not to mix lead and CA, it's this article that is shared (have done so myself). But has that reaction happened to anybody else? Lead fishing weights and CA are common modelling materials. Tail-sitting (or prevention thereof) is also a common problem. Surely somebody else must have tried fixing lead weights with a good amount of CA. But it's always this example that's brought up. Wondering whether there were other factors at play here that led - :P - to this unfortunate event. A certain blend of lead? Were other modellers just lucky that the "crystals" had enough room to expand? Just wondering...  ???
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: finsrin on September 21, 2020, 07:51:57 AM
Have used CA & lead for nose weight.  Never heard of or seen this.  Guessing quantities were small enough that this issue did not show.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: Kerick on September 21, 2020, 09:45:48 AM
I have used lead and CA in many models and only had one occasion where the combo actually attacked the plastic. The plastic turned brown and became very brittle where the CA touched it. The white powder hasn’t caused a problem for me, so far at least.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: Chris on September 21, 2020, 02:54:28 PM
In the UK and EU (bit early for separating them but got to start sooner or latter) a lot of things we think of as being made from lead, particularly pellets, aren't in fact on environmental and H&S grounds. It is complicated especially when it comes to fishing weights where there are upper and lower weight restrictions on what can be used. So a lot of the time we don't see the reaction because it's not lead we are using.

Not sure where else in the world that applies ?



Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: Frank3k on September 21, 2020, 11:10:13 PM
@Chris - that makes sense; some metals may react differently to CA. Zinc Most of the searches on CA + lead are from modeling groups.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: Kerick on September 22, 2020, 02:04:18 AM
On a couple of models I was able to “trap” lead weights by glueing sprue to box it in without glueing the lead directly. It rattles if you shake it but I don’t care about that.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: jcf on September 22, 2020, 03:47:40 PM
I guess it must enable the creation of lead carbonate, lead shot also reacts with PVA.

From a miniatures blog entry on 'lead rot':

"The chemical process is: Acetic and some other acids, in the presence of carbon dioxide, catalyze with lead
to produce lead acetate and lead hydroxide. Lead acetate and lead hydroxide together react with carbon dioxide
and form lead carbonate. Lead carbonate then releases acetic acid and the process becomes self-sustaining.
It is important to recognize that the formed lead carbonate is not just a substance clinging to the surface of a
casting, it is the surface of the casting transformed to powder. For practical purposes, a portion of the lead is
gone and lead carbonate is left in its place. The lead carbonate releases acetic acid which can continue the
process until the lead part is progressively consumed from the outside."

Evidently a major culprit in starting the process is wood:
"Wood exposed inside display cases with relatively stagnant atmospheres will create an acetic acid-laden
micro-environment where lead artifacts will corrode even without being in physical contact with the wood."
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: The Rat on September 23, 2020, 05:05:10 AM
I just use white glue, after roughening the surface to provide a better grip.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: Frank3k on September 23, 2020, 07:57:04 AM
But aren't most white glues PVA?
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: perttime on September 23, 2020, 01:13:16 PM
Lead in its solid metallic form isn't too bad. Once you heat it to create fumes, or mix it with something that oxidizes it, it can get nasty. Like ... the ground here generally "cocoons" pellets or bullets so that the lead stays where you leave a pellet or bullet. I heard that a shooting range had gone environmental and switched from lead to steel shot. They were OK with the lead "cocooned". Then, the steel started oxidizing (rusting) in the ground and started a reaction with the lead too. Nasty.
Title: Re: Don't mix lead and cyanoacrylate (Superglue)
Post by: Robomog on October 25, 2020, 05:57:10 PM
Must admit I have had no problems (yet) with fishing weights and CA, however would recommend leaving it a day or two to "gas off" before sealing the fuselage
Or  fitting any transparencies

Mog
>^-.-^<