Thread: Cell Rot

Everyone knows that cell rot is a common occurrence in razors with celluloid scales. Everyone seems to agree that some colors are more problematic than others, for example it's common in the yellowish celluloid scales like those on the DD, but not common in black scales. I wondered why that would be.

Celluloid was manufactured from the mid 19th century until about 1940. It is made from nitrocellulose (gun cotton) and camphor. A lot of people people have long put a piece of camphor into their tool boxes, since it emits a gas that creates a light coating on metal that prevents rust. So clearly the camphor is not the culprit. Looking at 19th century pigments it turns out that one of the most common pigments used for reds and yellows was iron oxide (rust). So, I'm speculating that the outgassing of the camphor is carrying traces of iron oxide (and other pigments) and depositing them on the blade as a thin film. The rust then quickly spreads from that iron oxide rich deposit. What do you think?

DD scales in question had no Yellow pigment
They were White and Clear
They are also Catalin and the recipe changed in the later years

Part of the problem with Cell Rot is that there are few rules because there were so many recipes

The idea that Light colored scales / Bright colored scales are more susceptible might not actually be truth, it very well could simply be the recipe

The Celluloid actually breaks down and Off-Gasses... The off gassing is nitric acid or acetic acid.


Try searching Neil Miller & Cell Rot together

The Late Mr. Miller forgot more about Celluloid then most of us will ever know

ps: There is also a ton of info available away from the SR aspect if you look at Celluloid Collectibles and also the Film Industry's problems with Cell rot

ps: There is also a ton of info available away from the SR aspect if you look at Celluloid Collectibles and also the Film Industry's problems with Cell rot[/QUOTE]

Good point Glen! I can remember a few years back when those in the movie industry were trying to preserve/restore a lot of the old movies as they were done on film that was either celluloid or contain some celluloid, I don't remember exactly which. I guess we actually lost some of the old movies because of cell rot.

The off-gassing is also flammable - a well known hazard of old accordions covered in pearlescent celluloid which can burst into flame when the player lights a cigarette, etc. This finish is known in the trade as MOTS - Mother of Toilet Seat!

^^Wow that would make for quite a show!

Early billiard balls as well! The Earliest Plastic Billiard Balls Had A Habit Of Exploding

I would pay cash to see that happen in a billiard game at one of our local taverns.

It's possible light plays a role too and the light and clear transmit light through them while black does not.

I have read this so many times trying to memorize it :<0) But then I can go look anytime I want and it really doesn't matter. It's the result of it I deal with the most. The sound advice is keep it dry, cool , and out of the sun.

Celluloid wiki ..... https://en.wikipedia.org/wiki/Celluloid

Deterioration

Many sources of deterioration in celluloid exist, such as thermal, chemical, photo-chemical, and physical. The most inherent flaw is as celluloid ages, the camphor molecules are ‘squeezed’ out of the mass due to the unsustainable pressure used in the production. That pressure causes the nitrocellulose molecules to bind back to each other or crystallize, and this results in the camphor molecules being shoved out of the material. Once exposed to the environment, camphor can undergo sublimation at room temperature, leaving the plastic as brittle nitrocellulose. Also, with exposure to excess heat, the nitrate groups can break off and expose nitrogen gases, such as nitrous oxide and nitric oxide, to the air.

Another factor that can cause this is excess moisture, which can accelerate deterioration of nitrocellulose with the presence of nitrate groups, either newly fragmented from heat or still trapped as a free acid from production. Both of these sources allow the accumulation of nitric acid, a main component of acid rain that leads to corrosion of the environment. Another form of deterioration, Photo-chemical, is severe in celluloid because it absorbs ultraviolet light well. The absorbed light leads to chain-breakage and stiffening.

Accordions even over 100 years old covered with thick celluloid might be in pristine condition, while on the other hand thin celluloid film reels are often melted in an unrecognizable solid block after tens of decades in storage.

Well, it makes perfect sense that nitrocellulose would produce nitric acid, since that's a primary component of it's production.