White metal anchor corrosion on museum model

[JerseyCity Frankie]

Recently visited the Mystic Seaport Museum in Mystic Connecticut and saw this superb model of Flying Fish. The cased model was excellent, great construction detail and rig. The unpainted model was aging very nicely, except for the anchors which were blooming with scale and deeply corroded. That old white metal corrosion again. In other cases I’ve seen painted anchor bursting like stuffed animals, white fuzz emerging from cracks in he paint caused by the expansion of the metal. In this case the corrosion looks like brownish orang bubles. The base under the Bow was discolored from material dripping off the anchors. Also two copper hull plates had come off. Oddly, the figure head appears fine, sugesting it’s made of stronger stuff. Real gold?

Edited August 12, 2018 by JerseyCity Frankie

[Altduck]

I'm sorry, but I can't resist -

 

It's a Goldfish

 

[druxey]

Corrosion could also be from lead as well as white metal. However, lead salts are more usually whiskery or powdery and white (lead carbonate).

[wefalck]

White metal contains lead, which is the culprit, I think. The worst cases (pun intended) are glass cases fitted with silicone - it gives of acetic acid fumes, which speeds up corrosion in form of lead acetate.

[John Allen]

5 hours ago, wefalck said:

which speeds up corrosion in form of lead acetate

Welfalck,

 

That  little tidbit of formation worth a million dollars, thanks for posting.

[keelhauled]

Yep, I have a constitution with wonderful corroded anchors.  someday, I need to get the case off and replace the anchors, which are attached to the ratlines.  what a bummer!!  Thanks for showing what happens with this metal in an air tight case!  It's heart breaking to put all of that care into the build to see this happen to your model.

Edited September 8, 2018 by keelhauled

[xken]

Something else is also going as well, I see what looks like a drip spot from a liquid on the base wood surface. Could drastic swings in temperature cause moisture condensation on the anchor with enough buildup to drip over time?

I have also see this type of corrosion on parts using blackening agents and not being rinsed thoroughly with water after being treated. This usually starts in a hole or recess in a part.

[jud]

Was a discussion on this subject several years ago, venting the case using cotton waist as a dust filter was one of the solutions.

[Thistle17]

I had this unhappy event back in the 1980's with my Bluenose model. I had that powdery white dust all over the encased model. Two years ago I removed the affected elements, cleaned them up and repainted the one's I could salvage. They have yet to go back on the model as I was waiting to see if the problem would return. I have kept them inside a plastic case with no ill effects evident. To address the problem with the encased model I drilled 3 vent holes at the top of the back of the case and provided some venting in the case floor hidden by a name plate support. Since doing so I have had no sign of metal breakdown. I even installed a miniature muffin fan controlled by a timer to see if that would do the trick. It seemed to do the job.  So then I went completely to passive venting and that has worked as well. My case is glass on sides, front and top with mahogany framing. I have suspected the floor of the case might be part of the problem as it is mahogany plywood. They use formaldehyde in the plywood adhesive so watch out for that.

Joe

[druxey]

Venting a case will help, but not necessarily eliminate the issue. Sealing lead-bearing metal parts before they deteriorate with something like clear nail varnish will also help, but is no guarantee against break-down over time. The most effective measures? Never use lead or white metal parts. Replace them with lead-free fittings and dispose of the originals using hazardous materials handling and at a suitable waste facility.

[keelhauled]

Druxey is right.

 My anchors were sealed with nail polish then painted with enamel (I didn't do this to seal the anchors for corrosion, but because I thought that the black enamel paint would be less likely to scratch to the metal during rigging).  The anchors split open with the corrosion.

[Bob Cleek]

Without comment on whether the model (partially) in the photos is worthy of museum display, I'm surprised that a museum of Mystic Seaport's stature would display a model so obviously in need of conservation. Not only are the anchors corroding, but the copper bands on the stock are broken (perhaps by the expansion of the lead oxide beneath the stock halves,) but also there are rigging chains detached and hanging loose and staining on the base from apparent condensation. Not only have some copper plates come adrift, but the coppering and parts of the chains in the close-ups appears to have developed a green patina betraying that it has been stored in some time in an excessively humid environment.  Among curators, these are obvious problems that require prompt attention. Perhaps Mystic simply left it on display pending future-scheduled restoration.

 

If anyone is interested in what seems to be the "last word" on ship model lead corrosion, the USN NAVSEASYSCOM's research report is highly informative.  It can be found on line here: https://www.navsea.navy.mil/Home/Warfare-Centers/NSWC-Carderock/Resources/Curator-of-Navy-Ship-Models/Lead-Corrosion-in-Exhibition-Ship-Models/

 

 

 

[wefalck]

That report is a very good practical summary of the problems and solutions !

[Altduck]

Wow!  Interesting reading. 

 

I think it can be summed up as follows:

 

- Don't use lead or lead alloys on your models.

- They will live longer, and so will you.

[wefalck]

Plus

- don't use silicones

[JerseyCity Frankie]

The model depicted wasn’t on public display. It’s across the street in their vast storage facility.

[Bob Cleek]

7 hours ago, JerseyCity Frankie said:

The model depicted wasn’t on public display. It’s across the street in their vast storage facility.

That explains a lot.  It could well have been donated to them in that condition and awaiting disposition.