Aerometric P51 Chromed Sac Cage Corrosion - How To Deal With It?

[Jerome Tarshis]

To be honest, in my engineering career of over 30 years, I have never heard of anyone deliberately plating Aluminium. Maybe it's because it flakes off in the end.

 

Not to appear to be splitting hairs, but where did anyone say Parker plated aluminium? On p. 58 of the Shepherds' book on the Parker 51, the diagrams of the early filler sleeves say "chrome-plated steel" and "polished aluminium."

 

This still leaves us with FarmBoy's chromium-free analysis results, though.

[Matlock]

 

Not to appear to be splitting hairs, but where did anyone say Parker plated aluminium? On p. 58 of the Shepherds' book on the Parker 51, the diagrams of the early filler sleeves say "chrome-plated steel" and "polished aluminium."

 

This still leaves us with FarmBoy's chromium-free analysis results, though.

 

As Ron Z states. "You see this on the early "press 6 times" fillers, which screw onto the thread busing. They are aluminum, plated with chrome." I have a 1948 Demi and nearly all the plating has flaked off and the sleeve is definitely aluminium.

[Intensity]

The appearance of the metal under the plating on my "press 6 times" sleeve has the look of raw aluminum to my eyes.

[Matlock]

The appearance of the metal under the plating on my "press 6 times" sleeve has the look of raw aluminum to my eyes.

 

I have had a closer look and used a knife to make a small scrape. It is very soft so not steel but could be a zinc alloy of some sort, although it looks to be aluminium.

[pajaro]

When you sell one of these pens with the corroded filler you might take a hit on the price. Probably not so bad on common colors, but if I were buying a Plum demi or full size 51, I would want a significant discount. This could make you want to replace the filler if it's corroded before you sell.

[Ron Z]

Not to appear to be splitting hairs...

 

Split away! Books don't always get it right. Take the published myth that Parker VP filler necks are made of glass. I have yet to see glass react with methylene chloride like the fillers do. They just happen to be made of a very clear, very brittle cast acrylic.

 

I've dealt with enough pens and other items to know corroded aluminum when I see it - and you do see it on the threads inside the sac guards. Steel doesn't corrode into a white powder, it rusts. However aluminum does.

[Matlock]

 

Split away! Books don't always get it right. Take the published myth that Parker VP filler necks are made of glass. I have yet to see glass react with methylene chloride like the fillers do. They just happen to be made of a very clear, very brittle cast acrylic.

 

I've dealt with enough pens and other items to know corroded aluminum when I see it - and you do see it on the threads inside the sac guards. Steel doesn't corrode into a white powder, it rusts. However aluminum does.

 

Thanks for that Ron, I plumped for aluminium although, as I said in my last post, I felt it could just be a type of zinc alloy. As far as the VPs are concerned, I have three (one is a Holy Water Sprinkler) and it always makes me smile when it is claimed that the filler neck was glass.

[inkstainedruth]

When you sell one of these pens with the corroded filler you might take a hit on the price. Probably not so bad on common colors, but if I were buying a Plum demi or full size 51, I would want a significant discount. This could make you want to replace the filler if it's corroded before you sell.

 

I think that's what happened with the one I bought. The previous Plum Demi I'd seen on eBay went for something like $102 US (I dropped out in the low $70s). Mine? Under $72, including shipping. But I didn't care that it wasn't "minty minty" -- mine doesn't sit in a display case. It gets used. The fact that I think it might have a medium nib on it is just a bonus. But while there were a bunch of other bids on it, I wasn't outbid over the entire week of the auction (there had been a bid for the minimum amount when I saw the listing, and this was one time when I didn't futz around with nickel-and-dime bids. But I still expected to get outbid, because it was Plum, and because the auction ended late afternoon on a Saturday, when I wasn't going to be home to monitor it (in fact, I ended up being out really late that night, and almost didn't check the results until the next day -- on the assumption that I was going to be outbid the way I had with the previous one).

Ruth Morrisson aka inkstainedruth

[Jerome Tarshis]

Although it is a commonplace that not everything one may read on the Internet is true, I am old enough to remember that not everything one reads on the printed page is true.

 

Where I thought we were after FarmBoy's announcement of no Cr is that we as a community have perhaps been misled by seemingly authoritative sources. I am the last to imagine that the Shepherds' book, said to have been informed by access to Parker's records, is free from error. FarmBoy and I have discussed that point, though not w/r/t filler sleeves.

 

I had hoped, not to assert that in my opinion the underlying metal was steel, but to launch a little inquiry into what we know about those filler sleeves and what the best information says. As a journalist I've been forced to learn that "the best information" need not be in an obvious place, and when I consider that some of us possess all kinds of technical documentation I'd like to consult that and throw some light on how it happened that some seemingly wrong ideas about Which Metal??? have come into our discourse.

[FarmBoy]

The XRF analysis was indicative of a nickel plated aluminum filler sleeve.

 

Just for clarity, we tested an unplated and a plated and corroded filler sleeve. Both were the early press 6 times.

There was NO Chromium in either sample. The only real difference between the two was a peak for Nickel in the one that was flaking and corroding.

[Ron Z]

So is it possible that the corrosion is galvanic action?

[richardandtracy]

Hmm, haven't got my galvanic potential charts at home, but IIRC aluminium is pretty close tho the top of the chart, and Nickle towards the bottom. That PD could be enough to cause corrosion at RH > 60% with no liquid water present, just relying on the surface condensate to complete the circuit.

 

Regards,

 

Richard.

[pajaro]

What might be important to some owners would be if there are any sources of replacement fillers, and are the replacements doomed to corrode no matter what we do.

[FarmBoy]

What might be important to some owners would be if there are any sources of replacement fillers, and are the replacements doomed to corrode no matter what we do.

There are sources of replacement filler sleeves. Unfortunately most come from other pens. Typically the pricing is such that it is more economical for corroded pens to become parts sources for other pens.

 

When quoting prices for parts one usually gets the “I can almost but a whole pen for that” comment to which one offers the reply of “I agree, eBay is a good source of parts pens.”

[Intensity]

If it's a widespread issue for the coated sleeves and does not inhibit normal operation of the pens (i.e. basically just a cosmetic eyesore), combined with the fact that it's invisible once the pens are assembled, I would just take it as part of the quirky character of vintage P51s. Unless someone keeps an absolutely pristine P51 uninked and unused, and this issue develops, a pen in regular use will acquire various imperfections with time anyway.

[Ron Z]

Keep in mind that these sac guards screw onto the thread bushing, while the later ones are a press fit. They are not interchangeable. If the corroded sac guard bothers you, be prepared to replace the thread bushing too.... The end of the barrels for these pens is threaded all of the way to the end, while later ones often have a machined threadless step in the end. One can be cut into the end, but that is another factor to think a about.

[Paul-in-SF]

I'm glad I discovered this thread. I have a full-size aerometric Plum from 1948 with a Press 6 Times sac guard that has something, which I am supposing is corrosion, over most of the sac guard, but so light that it is only visible through a 10x loupe and I can't feel it at all. No apparent flaking or powder yet.

 

On 4/19/2019 at 12:46 PM, Ron Z said:

Keep in mind that these sac guards screw onto the thread bushing

 

I would really like to take a look at the threads where it attaches to the section to make sure they are not corroding, and maybe to apply some silicone grease if appropriate. I have tried unscrewing mine with my hands, and then with section pliers on the section and my hand on the sac guard, and then by ultrasonic in warm tap water, and it does not budge. Would applying heat very cautiously be appropriate as a next step, or is there a better way? Thanks.