Cellulose - the private life, and other materials

Rather that clutter Justin’s build thread with glue matters I thought that I would reply to Bill in a new thread:

If it gets a life of its own, so be it!

Sailtwister (Bill) wrote:
<<I didn’t know that! However, I think there is a difference between acetate and celluloid. The story I heard was that Ambroid was originally made by dissolving old B&W Acetate movie film, resulting in it’s amber color (hence it’s name), which apparently had a relatively short lifespan as film, and this was one of the reasons they switched to celluloid for the movie industry. However, I would suggest that if acetate and celuloid really are the same, it is still being used in the film industry, since there are still many older movie theaters in this country that haven’t been able to afford the new digital technology. I think most of the actual filming process is still done on tape (shooting & editing) but then converted to film to distribute to the older theaters.>>

Taking this a bit at a time:
Celluloid - probably the second plastic to get into use- is cellulose nitrate in a transparent form. (Yes, you with the raised hand; guncotton is also cellulose nitrate extruded as threads as a propellant explosive)
Films were all celluloid until non-flammable film stock was developed, and running celluliod close to a very hot bulb is bad news - see all the movie theatre fires!

All film stock now is non-explosive, only the achives are still nitrate stock, and sadly they self-destruct even if kept in the dark and very carefully.

Dope (shrinking - aka nitrate dope) is cellulose nitrate and acetate dissolved in light solvents - highly flammable, but not explosive. Non shrinking dope is, (I believe) celluluse butyrate similarly dissolved but it seems to be found only in the US.

Going back to 1918 an dthe end of WW1 - Dupont had been making guncotton in staggering quantities - had thousands of ton without a home, and tried dissolving it in various solvents to make lacquers - the result was cellulose paint (Belco in the UK) which covered cars from the 20s to about the 70s.
Another spinoff was the airbrush - required because using cellulose finishes with a brush was near-impossible (but not quite)

A quick return to cellulose - its a natural molecule.
Balsa is tubes of cellulose held together lightly with a natural resin called lignin. It is the lightest hardwood cos the tubes are large and there isn’t much heavy lignin.

I don’t want to bore anyone - tell me to stop or go as you prefer

Hi Andrew,

This thread has caused me to get on the web and do a little research, which as you might guess, has resulted in more information than I (and probably anyone else) really wanted. This is one of the problems of the internet, it’s just too easy to spend time trying to satisfy one’s curiosity, rather than using that time productively - building & sailing Footys! I had forgotten that Cellulose Acetate was the safer development that replaced Cellulose Nitrate, and when used in film was referred to as ‘Safety Film’. I did find that the two types of plastic commonly known as celluloid (nitrate & acetate) can actually still be found in fountain pens (that is, if you can find a fountain pen). Also, that celluloid is still used in the production of ping-pong balls (38mm & 40mm dia.), as well as guitar picks and Celluloid Drum sets. Along the way, I found information on The Great Ping-Pong Ball Experiment which involved sending a fragile Ping-Pong on a journey the length of the Nile River, and also that Rayon, invented by two Swiss brothers in the 1920’s, comes from celluloid.

Like I said, more than I really wanted to know, and there’s lots more out there on the web for anyone who has the time to look it up!


I thought I remembered Acetate from my injection molding days. Acetel as it was called, was used in certain products, pens included, but it was done away with pirmarily due to newer resins being created. Acetel was good for (translucent parts) replaced by Crystal Styrene and others. I worked for Sheaffer Pen Corp. I wish more people still wanted good fountain pens. They went out of business, due to cheap replacing good…

So Andrew, Ambroid is so good because of the fact that the Cellulose in the glue and the cellulose in the Balsa blend so well? I am thinking that’s what your take here is?

Hi jusval,

You might find a couple of the websites I found on the web interesting:

About Schaefer pens, they still have a website: http://www.sheaffer.com/

And about celluloid pens check out: <http://nibnumpty.wordpress.com/2008/07/13/a-cluster-of-celluloid/>

Bill Nielsen
Oakland Park, FL USA


<<So Andrew, Ambroid is so good because of the fact that the Cellulose in the glue and the cellulose in the Balsa blend so well? I am thinking that’s what your take here is?>>

I would like to think so, but I think it’s coincidence. Balsa cement works well partly because it penetrates the tubes in the end grain of the balsa and so partially impregnates the wood in the area of the joint.
If you hear about “double-glueing” that is what was going on - the first application penetrated the tubes and evaporated, and if you assembled the joint there was not much adhesive left in the joint, and none to make a fillet around it, so you let the first application dry (minutes only), then applied more and made the joint.

I’m pretty certain that acetal is not (closely) related to cellulose or any of the common acetates, but don’t know in detail what it is and where the name comes from - useful stuff, though.


In my Ain Plastics catalog “Acetal” is used synonymously with “Delrin”. “Delrin” is a like “Teflon” but much harder, although used for pretty much the same purpose , as a slippery plastic bearing surface.

My kingdom, my kingdom for a chemist!— to quote King Dick I.

On second thoughts, make that a polymer chemist.

Wasn’t that Dick III ?:graduate::devil3:

Hard to believe that Richard Crookback was a polymer chemist, but if you say so, Angus:D

He certainly is one of the prime examples of “history is written by the winner” and hence carries the can for the murder of the two princes in the tower, the current credit crunch as well as the description of being a crookback!
Certainly not guilty of any of the charges - and his preferred weapon was an axe, so the right shoulder was greatly overmuscled (like a plasterer)

Any road oop, Delrin is Dupont’s trade name for their acetal resin (strictly a polyacetal or Polyoxymethylene ) and indeed it is hard, slippery and a great bearing material - but completely unrelated to acetates.
Department of “every day you learn a new thing” Apparently glucose and maltose are acetals!