Thread: On celluloid process - (Not exactly about straight razors)

Hi,

I was suggested by mentor member to post this video here.
It is not about straight razors but high grade craftsmanship ... so I think you could appreciate.



Lo.

Thanks for the informative video.I prefer more traditional materials like wood but I like the vid especially the greek map on a pen.

For those who don't know, Nitro cellulose is an explosive and a quite powerful one too, more so than TNT.
It was used in mines and bombs in the days, now only found in UXO (Unexploded ordnance) where its decomposive behavior makes it nasty to work with.
Don't worry tho, in cast form as we see it on razors it's extremely hard to set it off.

Excellent and informative video - many thanks for posting it.

A small detail concerning the manufacturing process is wrong, though - namely that 'nitrocellulose' is extracted from the cotton bolls: it is not.

The boll is almost 100% pure cellulose. The cotton wool extracted from the bolls is then 'nitrated' by steeping it in acids, the main one of which is nitric acid. After copious washing we now have nitrated cotton, also known as gun cotton for its use in old fire arms. It looks like cotton wool still, but is dangerously explosive and unstable.

To get the goopy mass used to make celluloid the gun cotton is steeped in a mixture of aromatics like ether and alcohol. The video leaves out all these steps by suggesting that cotton plants produce bolls made of nitrocellulose, which is not true.

Suppose for a minute that they did: we would have whole plantations spontaneously blowing up, not to mention the plight of the poor souls 'gathering in the cotton' as they used to sing about in tbe old non-pc movies. They would have had precious little to sing about while risking having their hands blown off at any moment!

Still a great video, though - thanks again.

Regards,
Neil

Originally Posted by Neil Miller

Excellent and informative video - many thanks for posting it.

Thanks

To get the goopy mass used to make celluloid the gun cotton is steeped in a mixture of aromatics like ether and alcohol.

IIRC they use camphor to "plastify" the nitrocellulose

Lo.

Originally Posted by oxomoxo

IIRC they use camphor to "plastify" the nitrocellulose

Lo.

It certainly was, but it was not added at the nitration stage.

After copious washing the guncotton was immersed in a mix of ether and alcohol to dissolve it into a syrupy goo. Some users - myself included - also added some chloroform at this stage. The end product is known as collodion. For photographic purposes small amounts of bromide and iodide salts were added (I prefer to use 'double cad' - cadmium bromide and cadmium iodide) and the mixture was left to age. No camphor was used at all - it negates the photographic qualities of collodion. In the 1860s and later it was used for flowing onto glass plates to make photographic negatives, or ruby glass for directly viewable ambrotypes or onto thin sheets of tin covered in a layer of bitumen (tintypes) that could also be viewed directly. The collodion covered plate had to be 'salted' in a bath of 'lunar caustic' and exposed immediately, hence the term wet-plate.

Lunar caustic is just a fancy name for a bath containing silver chloride. I suppose the first part of the name comes from the similarity of the colour of the moon and silver, but in practice they could just as well have called it dark brown caustic. If you drip it onto anything, as soon as sunlight hits it, it goes a dark brown black colour. Get it on your fingers and hands - an inevitability in my experience - and they too go this colour. For months. It does not wash off. And it is caustic. The silver chloride was purchased as small crystals. Get it on your skin and it burns a hole in it. Get it in your eyes and you go blind. A caustic pencil was prepared from it to burn off warts. For some benighted reason, a much diluted mixture was put into the eyes of newborn babes until recently, particularly in the deep south and third world countries. Sloppy hospital practice such as letting it partially evaporate and consequently concentrate the solution caused blindness and pain to many an innocent newly born babe.

Hundreds of people set up as photographers at that time, taking and processing images on the spot, depicting the civil war, soldiers and indian braves. These are now very valuable.

The other type was mixed with camphor to give a plastic like film once the solvents had evaporated. Once again it was used by photographers, but for cleaning lenses. You pour a puddle of it on the lens, let it dry and peel it off, and it takes all the dirt and dust off without scratching. Astronomers use it for cleaning telescope lenses, and it was the basis of an early field dressing later known as plastic skin.

It was used camphorated as early film anb motion picture stock, but was prone to explode when the fancy took it. Whole factories went up inflames, as well as movie storage depots and cinemas. Incinemas it was usually the poor projectionist who got incinerated, but there were some terrible fatalities that prompted Kodak to formulate 'safety film' which, btw, was not particularly safe or stable. Some early movies are lost forever to us, and a great number have been badly damaged due to the phenomenon of 'vinegar syndrme', a direct consequence of the switch fron cellulose nitrate to cellulose acetate in an attempt to control sontaneous ignition of fim stock.

The syndrome affects many old celluloid products, including razor scales. Here, we refer to it as cell-rot.

Regards,
Neil

The curse of knowing things!
You want to see a videos about something to see if you can pick up something new... and all you learn is how little the people making the video really know!

Thanks Neil for this valuable piece of your chemical experience

Originally Posted by Neil Miller

consequence of the switch from cellulose nitrate to cellulose acetate

Do you mean that Celluloid (cellulose nitrate) spontaneously turns into acetate ?

Is the 'volatile' / 'free' part of acetic acid in that process (the one that corrodes our razor blades) precisely due to the fact it came from cellulose nitrate and so would possibly be only partially transformed ?

Or would that process occur also with supposedly more stable Rhodoid (cellulose acetate) ?

Thanks for your insights.

Lo.

Lo,

There are two main types of celluloid:

1. Celluloid Nitrate - the earlist version developed by Parkes and sometimes called Parkesine, and
2. Cellulose Acetate.

The first was used to make things like billiards balls - which problematically exploded when they hit each other, making for quite an exciting game I should think! It does not contain acetic acid (sulphuric and nitric acid was used, a greater ratio of sulphuric to nitric lessens the explosive nature of the beast) neither does it spontaneously generate acetic acid.

The nitrate version can still affect razors, although scales made from it are rarer. It releases nitric acid vapour and sulphuric acid vapour that attacks metal.

The commoner acetate variety releases acetic acid as well as other acid vapours, but the smell from the acetic acid overwhelms everything else hence the vinegar smaell. Vinegar is a very much diluted form of acetic acid. The acid, in its crystalline form (glacial acetic acid) is strongly corrosive, damaging lungs by inhalation of the fumes, for instance, and burning the skin. It too corrodes metal.

Whether the celluloid in question degrades or not is largely due to how it is made. Washing after nitration is critical - it may go on for days and weeks. Without measurement, there is no way to know whether the critical level of nitration has been passed and in the old days I doubt that they bothered too much. Although chiefly used as a plasticiser, camphor does help to prolong the life of celluloid in correct quantities. You can smell it more in cellulose nitrate than cellulose acetate (moth-ball or medical smell) but the vinegaqry smell of degrading cellulose acetate masks it.

Additionally, cellulose acetate used wood shavings as part of the mix - to get the cellulose cell walls from it - and it is hard to make anything archival from wood pulp - even paper turns brown and flaky if made from wood pulp rather than pure cotton fibre.

Another factor is how transparent the celluloid is. Fillers (like powdered asbestos) where used to make it opaque. If it is very opaque it is likely to survive for a very long time indeed. Where you have mottled scales using translucent and opaque celluloid you can often see a pattern on the razor blade where the light areas have degraded and released gas and the opaque areas have not.

Curing is another factor. As it ages, celluloid becomes smaller in every dimension. That is why you often find razors with translucent celluloid scales, like Dubl Ducks, that are trapped up against the wedge in a set of deformed and twisted scales.

One last thing that seems to increase the rate of breakdown (all plastics degrade over time) is the amount of exposure to UV radiation - this seems to hasten the process.

I don't know much about Rhodoid other than it was formulated by May & Baker, who I worked for as a short time as a grade 4 lab technician more years ago than I care to remember. Typically I left May & Baker for a gruelling construction job because it paid £20 a week more - the following week M&B sent me a cheque to include a pro-rata of the new £50 salary increase that was backdated to the week I left. Call me Lucky - not!

I should imagine that as it was developed later (mid 1930s) by a reputable laboratory, then it ought to be more stable (as stable as any plastic can be, and that's 'not very') than earlier types of cellulose acetate, but I don't really know.

Regards,
Neil

Then, all "progress" is not!
Lots of material has been and still is developed only to get around some patent.