Does A P51 Hood Have To Be Shellaced In Place?

[mariom]

When screwing a P51 aerometric hood (with the o-ring seal) into place, it seems to go on tight enough that it won't come loose without a fair bit of effort. The shellac seems superfluous, and just makes hood removal more difficult in future. I would expect the O-ring is there to seal against possible leaks.

 

It is really necessary to have the shellac holding the hood on? Does it server some mysterious purpose that I'm missing?

 

Thanks

 

Mario

[dragos.mocanu]

I also have a "51" Special that has an O-ring sealed hood, and have never had any problems with leaks! I actually think that shellac is just a crude (and sometimes messy or even damaging) alternative to the special sealing cement Parker used when assembling their pens.

[Chrissy]

No it doesn't have to be shellaced in place.

[joss]

The mystery that you refer to might be that earlier P51s did not have that O-ring. These hoods were cemented and my idea is that it is safer to shellac them when reassembling the pen. Alternative is to test write the pen and shellac the hood only when there is a leakage.

 

If the pen has an O-ring in good condition, there is no need for shellac.

[kirchh]

Parker's circa 1960 repair manual says, "the Aero-metric shells require enough cement to seal and anchor them permanently in position. Therefore, the more cement used between the shell and nipple without waste, the better the shell will hold."

 

--Daniel

[Flounder]

Don't cross the streams! I remember in fitful, dread laden dreams the O-ringed 51 that had shellaced threads and a shellaced O ring. The hood was a horror to release.

[kirchh]

Yes, a modest amount should do the trick. I prefer section sealant, but I don't have really strong feelings about it either way.

 

--Daniel

[Ron Z]

O-ring or no, you should use some sealant. Most pen mechanics use shellac because it keeps the client from casually unscrewing the shell and screwing up the alignment. But as Daniel has noted thread sealant will do just fine. I have encountered NOS 51s (as in the dust from manufacturing was still in the inside) that were sealed with a rosin based thread sealant, not shellac.

[PDW]

I use silicone [thanks for spelling correction, Daniel] grease to prevent leaks and firm-but-gentle tightening to hold it in place. I reason that the collector may need a deep clean one day so easier opening is an advantage, and I'm not worried about the hood accidentally unscrewing. It hasn't happened to me ... yet ...

 

I new await Ron Z's experience-based thunderbolt.

Edited December 11, 2014 by PDW

[kirchh]

I use silicon grease to prevent leaks and firm-but-gentle tightening to hold it in place. I reason that the collector may need a deep clean one day so easier opening is an advantage, and I'm not worried about the hood accidentally uscrewing. It hasn't happened to me ... yet ...

 

I new await Ron Z's experience-based thunderbolt.

I find silicone (note spelling) grease is a poor choice in this application. It is not a very good sealant, and due to its lubricating properties, it makes the hood more prone to loosening, which in turn often leads to over-tightening to keep it in place. Also, the grease tends to make its way to places it does not belong, and it's difficult to clean up. I'd avoid it.

 

--Daniel

[pajaro]

I use silicone [thanks for spelling correction, Daniel] grease to prevent leaks and firm-but-gentle tightening to hold it in place. I reason that the collector may need a deep clean one day so easier opening is an advantage, and I'm not worried about the hood accidentally unscrewing. It hasn't happened to me ... yet ...

 

I new await Ron Z's experience-based thunderbolt.

 

 

I find silicone (note spelling) grease is a poor choice in this application. It is not a very good sealant, and due to its lubricating properties, it makes the hood more prone to loosening, which in turn often leads to over-tightening to keep it in place. Also, the grease tends to make its way to places it does not belong, and it's difficult to clean up. I'd avoid it.

 

--Daniel

 

kirchh is right. This has been discussed here before, and the silicone grease easy fix is a sucker trap. Hood sealant has also been recommended, but the expert choice as I read it here seems to be shellac. It's easy enough to find in a hardware store, and it's easy enough to apply: thinly. It's easy to heat it to release the seal if you don't use too much. Just enough to seal the threads, and keep in mind you are not gluing the hood on. Remember you might want to get the hood off again, and apply shellac lightly, so you won't have to heat the hood until it deforms trying to release the hold of gobs of shellac.

[Ron Z]

 

 

I'm not worried about the hood accidentally unscrewing. It hasn't happened to me ... yet ...

 

Yet, is right. I've done a few 51s in the last few years. Few hundred that is. Let me know when you catch up.

[Write Again]

What type of shellac do you recommend, Ron?

Edited December 11, 2014 by kovey10

[PDW]

I find silicone (note spelling) grease is a poor choice in this application. It is not a very good sealant, and due to its lubricating properties, it makes the hood more prone to loosening, which in turn often leads to over-tightening to keep it in place. Also, the grease tends to make its way to places it does not belong, and it's difficult to clean up. I'd avoid it.

 

--Daniel

 

 

 

 

 

kirchh is right. This has been discussed here before, and the silicone grease easy fix is a sucker trap. ...

 

 

 

Yet, is right. I've done a few 51s in the last few years. Few hundred that is. Let me know when you catch up.

 

I've had a look in Marshall and Oldfield (third edition) and they say of reassembling P51 Vacs (and by implication early aerometrics without a rubber ring), "Screw the hood back on again using heat. It is rarely necessary to reapply any adhesive. A little silicone sealant or rosin thread sealant at the top end of the threads where the shell meets the clutch ring is a good insurance policy against leaks." (p.71). This seems to be ambiguous since they may be relying on the presence of sealant remaining in the threads after disassembly (hence ‘reapply’), but this reading seems unlikely given the care they take elsewhere regarding reassembling pens, and uncertainty as what if anything was used when the pen reassembled by past repairers. Perhaps Laurence could elucidate.

 

As for later aerometrics, they make no mention of shellac or thread sealant when refitting the hood, but do say, “Add some silicone grease to the O-ring.” (p.73)

 

Either we have a difference of opinion here between distinguished and experienced repairers, or is there some slight difference in the approach needed for US pens (which Ron would have probably most commonly worked on) and UK manufacture which Marshall and Oldfield would have encountered?

 

Incidentally, they also say, “The nib and feed should be fitted in the collector such that the wide channel is above the top of the nib, but this alignment does not seem to be critical.” (p.73)

[Ron Z]

I use regular Zinsser shellac, as did Sheaffer. Take a look at this blog post. I've had a couple of people give me a sample of their custom mix shellac, and frankly I can't tell the difference once it's securing a sac. They say "It's stickier," and well it may be. But so is Zinsser once some of the alcohol has evaporated out of it and the cut (amount of alcohol used thin the shellac) is reduced.

 

There are indeed differences in opinion between pen repair people. I think that Marshall and Oldfield are right on using the silicone grease on the Aerometric in one respect. You need a little silicone grease on the 0-ring, or on the very lip of the shell (where the threads are cut away) not to act as a sealant, but as a lubricant. If you don't lubricate one or the other, the 0-ring can stick to the shell, or bind, as you screw it over the 0-ring. A little lubrication allows the shell to go on easily and reduces the chance of cracking the shell. Not that it's a big risk, but if you can reduce or eliminate stress when repairing a pen, you should. I put an incredibly small amount on a Q-tip and spread it around that little step at the end of the hood, but not on the threads of either the shell or nipple.

[kirchh]

I generally pre-lube the O-ring by wiping it with some non-linting cloth with a tiny dab of silicone on it; I wipe it firmly enough that there is only the minutest amount left clinging to the ring (it's essentially like wiping it off, really). That's all that's needed to allow it to cooperate with the hood during reassembly, I find.

 

--Daniel

[penrivers]

I had a conversation about it with Farm Boy, it happened that I sent him 3 Parkers 51 to tune up and buy 2 xf nibs ( dont worry Mr Pendleton, you wonderful works are still in the grey and cordovan 51), I told him not to shellac any pen so he kindly advise me an intermediate solution, to put silicone grease in it from Pendemonium, so I did it and is working well, in spite of the warnings days ago from Bruce in Ocala, perhaps I will clean them again and this time I will cover its threads with Silicone base heat sink compound from Radio Shack. Before that I used my pens for years with not stuff in threads and they worked absolutely fine.

[kirchh]

I had a conversation about it with Farm Boy, it happened that I sent him 3 Parkers 51 to tune up and buy 2 xf nibs ( dont worry Mr Pendleton, you wonderful works are still in the grey and cordovan 51), I told him not to shellac any pen so he kindly advise me an intermediate solution, to put silicone grease in it from Pendemonium, so I did it and is working well, in spite of the warnings days ago from Bruce in Ocala, perhaps I will clean them again and this time I will cover its threads with Silicone base heat sink compound from Radio Shack. Before that I used my pens for years with not stuff in threads and they worked absolutely fine.

Why would you choose heat sink compound for use on a pen?

 

--Daniel

[penrivers]

kirchh, on 12 Dec 2014 - 17:32, said:kirchh, on 12 Dec 2014 - 17:32, said:

Why would you choose heat sink compound for use on a pen?

 

--Daniel

Hi, no racional reason, maybe because is diferent to a simple portion of silicon grease alone. Aclaring that I havent done it yet, perhaps I woulndt do that.

Daniel, perhaps you have good reasons not to or do that, ¿can you develope a few lines on this matter ? please.

Edited December 12, 2014 by penrivers

[penrivers]

Clarifiying. All my 3 p51 have tiny silvered rings up of the hood. Make your assumptions.