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

[Intensity]

This is probably not an uncommon question for vintage Parker 51 pens, but I thought maybe there are some variations to the theme of advice, so here are some photos of what's been happening with one of my P51s (got it in that condition already):

 

 

 

The metal is clearly corroding/flaking off and some of that stuff gets stuck on the sac--don't know if that's a concern for the sac, is it?

 

I'm not sure how to best keep the whole thing clean and to delay the process of further deterioration. Is this something I need to worry about?

 

The pen otherwise is great and has no noticeable outwardly flaws--just fine microscratches visible only upon close inspection. Great XF-width nib.

[Mr.Rene]

I am not a Parker expert but the metal is called,technically, sac guard with pressure bar. If I am not wrong some sac guards were made in stainless steel and ..maybe later sac guards... were made with other material (not solid steel) and sac guard coated with layers of chrome or nickel..yours seems to be this one,maybe you need to re-plated the sac guard to remove corroding-flaking off damage...

[Intensity]

Interesting, that could explain why 2 out of 3 of my P51s don't have this issue at all, they could be using stainless steel parts. Thank you.

[Ron Z]

You see this on the early "press 6 times" fillers, which screw onto the thread busing. They are aluminum, plated with chrome. The later "press 4 times" fillers are all stainless steel, and are a press fit onto the thread bushing. You can take the loose stuff off with a stiff wire wheel, but there is not way to un-uglify them.

 

If you ever have to remove one, twist the sac guard back and forth to loosen. Work it off gradually it rather than just twist it off. Clean off the corrosion on the threads, and then coat the threads with silicone grease to prevent further corrosion.

[Intensity]

You see this on the early "press 6 times" fillers, which screw onto the thread busing. They are aluminum, plated with chrome. The later "press 4 times" fillers are all stainless steel, and are a press fit onto the thread bushing. You can take the loose stuff off with a stiff wire wheel, but there is not way to un-uglify them.

 

If you ever have to remove one, twist the sac guard back and forth to loosen. Work it off gradually it rather than just twist it off. Clean off the corrosion on the threads, and then coat the threads with silicone grease to prevent further corrosion.

 

 

Thank you! Yes, indeed, my non-corroding ones are the "press 4 times" sort, and this one is "press 6 times".

 

Is removing this part a last resort kind of thing that one shouldn't do unless doing more disassembly? I.e. should I attempt it to just clean this part and the external surface of the sac?

 

If I don't do anything, can I expect this part to deteriorate to the point of interfering with function, or is this just a cosmetic nuisance?

[surprise123]

It is rather confusing. I have one corroded "press 6" and one pristine "press 6". One is the regular model, one is ths Signet model.

[inkstainedruth]

Is removing this part a last resort kind of thing that one shouldn't do unless doing more disassembly? I.e. should I attempt it to just clean this part and the external surface of the sac?

 

If I don't do anything, can I expect this part to deteriorate to the point of interfering with function, or is this just a cosmetic nuisance?

 

I'm now wondering the same thing -- my Plum Demi Aero has some of the same sort of corrosion -- which I suspect kept the price down enough that I wasn't outbid on it. I had assumed that a lot of it was just cosmetic, since it didn't seem to affect usage at all. And since it's hidden by the barrel, it isn't obvious unless the pen is being filled.

I've had the pen about 5 years and have not have any issues with the corrosion, and I use the pen relatively often (although it's not in rotation at the moment).

Ruth Morrisson aka inkstainedruth

[mitto]

I have since sourced replacement NOS/good shape press 6 time aluminium sac guards for all my 1948-1949 production aero pens. However, the issue is, most of the time, just cosmetic. The corrosion, I assume, does not affect functionality.

[Ron Z]

It is mostly cosmetic. The inside is not plated. I suppose that you could nick yourself on a bit of loose chrome plating, so I tend to try to clean it back to where the chrome is still adhering to the base metal.

[Intensity]

As long as it's cosmetic, I'll just not worry about it. It's not great that the powdered bits are collecting on the silicone sac, but hopefully they are inert and have no bearing on any functionality or durability issues.

 

NOS sac guards would be nice to get though.

[FarmBoy]

If memory serves correct, these fillers are nickel plated. I don’t have the analysis results at hand but I recall being surprised at the lack of Cr in the mix.

[Intensity]

P.S.: just double checked my other two pens--looks like only one of them--a Demi size--has the steel "Press 4 times" guard. The other full-sized P51 also has a "Press 6 times" engraving but just no loss of plating except in a tiny area on close inspection. It probably wasn't used as much as the pen in the above photos.

[inkstainedruth]

It is mostly cosmetic. The inside is not plated. I suppose that you could nick yourself on a bit of loose chrome plating, so I tend to try to clean it back to where the chrome is still adhering to the base metal.

 

Good to know. I hadn't really worried about it up till this point and seeing this thread. But I'm not one of those "OMG -- must be minty minty NOS condition" people. I wanted a Plummer, and I'm quite okay with mine being "user grade" because I use it!

Ruth Morrisson aka inkstainedruth

[Intensity]

Indeed, it's cosmetic but invisible in regular use. Good enough for me, as long as there's no loss of functionality.

[Ron Z]

If memory serves correct, these fillers are nickel plated. I don’t have the analysis results at hand but I recall being surprised at the lack of Cr in the mix.

 

Interesting. The bright color and gloss would have one think that chrome is involved. Nickel usually isn't that bright or shiny.

[Matlock]

 

Interesting. The bright color and gloss would have one think that chrome is involved. Nickel usually isn't that bright or shiny.

 

I believe that the fillers are chrome as, quote "Nickel is very slightly yellowish and chrome is very slightly bluish, so nickel is warmer looking and chrome is bling-y-er." Not a very scientific explanation but it certainly matches my fillers.

[FarmBoy]

 

I believe that the fillers are chrome as, quote "Nickel is very slightly yellowish and chrome is very slightly bluish, so nickel is warmer looking and chrome is bling-y-er." Not a very scientific explanation but it certainly matches my fillers.

We did XRF on the filler shrouds. There was no Chromium in the flaking shiny stuff fillers. I can't seem to find the printouts of the scans but they may still be sitting on the instrument and I'll ask.

Farmboy

[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. Am also old enough to have been writing with an Aero 51 almost since the first year and reading about Parker 51s for decades.

 

The published material seems to say, pretty much uniformly, that those early filler shrouds were chrome-plated. FarmBoy says above that he was surprised his analysis showed no Cr in the plating material. Is there not internal Parker documentation that says what those filler shrouds were made of?

 

What I am coming to is the question "Does 'chrome-plated' actually mean, in the world of product description or even industrial chemistry, plating with the metal chromium? Or has "chrome" become something like "iridium," a word used by manufacturers generically to refer to hard tipping material, even though the manufacturer's engineers presumably know perfectly well there isn't any actual iridium in the nibs they are currently using?

 

Is it possible to find out when in the history of advanced Western society "chrome-plated" stopped meaning there was any Cr in the plating? This may also bear upon the description of pen caps and bodies as "chrome finish" or "chrome plated."

Edited April 18, 2019 by Jerome Tarshis

[richardandtracy]

When it comes to plating of steel, chrome plating usually means:

1. Base coat plating of copper
2. Intermediate plating of Nickle
3. Final plating of Chromium.

The reasons for this are that Chrome plates well on both Nickle & Copper but not steel, but the copper tints the colour of the chrome due to slight porosity of the chrome layer and reflection from the underlayer. Nickle does not plate strongly onto steel & peels off easily. So the Nickle needs to go on copper, which sticks well to steel. It's one heck of a palaver.

 

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. Or, because It's now & not the 1950's, and anodizing is more easily available than it was. I would be cautious of plating aluminium too, because of the oxide layer that needs to be very thoroughly cleaned off prior to plating (with a caustic solution), and the fact it's Young's Modulus is 70,000 N/mm^2. Chromium is 248,000 N/mm^2, which is close to the 205,000 N/mm^2 of Steel but no-where near that of aluminium. The net result would be a shear stress between the plating & base material if the aluminium flexed, causing increased risk of flaking off. The Young's Modulus of Nickle is 207,000 N/mm^2, virtually identical to that of structural steel.

 

Regards,

 

Richard

[Matlock]

When it comes to plating of steel, chrome plating usually means:

1. Base coat plating of copper
2. Intermediate plating of Nickle
3. Final plating of Chromium.

 

To be honest, in my engineering career of over 30 years, I have never heard of anyone deliberately plating Aluminium.

 

Regards,

 

Richard

Well Parker obviously thought it was a good idea but, thankfully, not for long.