Celluloid Outgassing- an understanding

[Jpdragons1]

In my humble opinion, celluloid outgassing is misunderstood. The two major components of celluloid are nitrocellulose and camphor. Neither one of these contribute to metal deterioration as a general rule. Camphor has been used by the military to prevent corrosion. Nitrocellulose lacquer has been used to protect brass and copper from tarnishing. So how is the metal deteriorating in our knives? We have to understand there is a galvanic pecking order among metals. Molecules of Metals with higher potential want to naturally migrate to a lower potential, or stabilize. What you are witnessing is the same type of activity that occurs on a boat if it is not protected.

When we seal away our beautiful knives in their wrappings, cases and containers, we are creating a mini trapped atmosphere of the gas that is emitted from the the celluloid composition that serves as a plasticizer. Even all modern plastics have plasticizers in them to preserve shape, strength and prevent brittleness. They are relatively unstable, some more than others, and they give off gases as part of the process of plasticization. When the plasticizers have become exhausted, the remaining compounds become brittle. Ever roll up an old carpet, once soft and luxurious, that cracks and falls apart?

The gases created in these closed environments are like a mini ocean. They allow molecules to migrate between metals of different potentials. There is a pecking order in metals, the more susceptible metals migrate to the less susceptible. One of the most vulnerable and therefore most likely to be cannibalized in any group is Zinc. If you place zinc in your boat’s system, it becomes the sacrificial (anode) and protects the (cathode) your prop and engine drive. Within a season, the zinc will deteriorate away. In that way, think of our tightly wrapped up knives as being in their own little conductive gas ocean.

Worse, plasticizers have some solvent capabilities which is what makes them plasticizers. When these gases leave the celluloid handles, they’ve served their purpose and should quietly disappear. Trapping them in wrapping or closed containers can cause accelerated deterioration of the celluloid and harm fabrics, other plastics, leather, wood, etc.

My suggestion is to take all of the packaging, cases, etc., and store them somewhere for safe keeping. Put your collection in a well ventilated area, preferably on inert glass or stainless trays. If you keep them in drawers, leave them slightly open. For the extra precautious, you can use small gauge telephone wire with alligator clips to clip the metal frames or blades to a common chunk of zinc.

This explanation is different and apart from normal atmospheric corrosion which is an oxidation, like rust. But the cure might be similar. If you use pliers in salt water, sticking them in a ziplock bag is a recipe for disaster; rinsing and drying them, treating them with a water displacement spray and hanging on a pegboard is the right answer. You are likewise interrupting a corrosive natural system.

To conquer the enemy, we must first know who he is and understand him. I hope this helps.

[royal0014]

Interesting hypothesis . . . .

[ea42]

Great post jpdragons1 I guess that explains why on many of the outgassing knives I've seen the portion of the blade that sticks out of a folding knife when closed is quite corroded while the portion that sits in the knife is usually in much better shape. The zinc in the brass liners on either side of the blade probably acts as the anode that you referred to. That's probably also why brass liners and pins are usually degraded to dust on severely outgassing knives. unfortunately all the preventative measures used to save the blades doesn't help those poor handles, once they start going it's pretty much impossible to stop it. Storing the knives in a well ventilated area very likely does prolong their existence though as does keeping them away from damp areas and sunlight. Funny that you mention the cracked open drawer, that's exactly how I store mine.

Here's a very interesting article on celluloid and what causes its degradation:


https://cool.culturalheritage.org/jaic/ ... 2-003.html

Eric

[knife7knut]

Interesting theory but it fails to explain another facet of celluloid degradation: that of why a cover & brass liner on one side of a knife will be completely eaten away while the other side is like new. I have had 3 knives that this phenomenon has occured.
I still believe that petroleum products play a role in creating the onset of degradation.

[stockman]

In my humble opinion, celluloid outgassing is misunderstood. The two major components of celluloid are nitrocellulose and camphor. Neither one of these contribute to metal deterioration as a general rule. Camphor has been used by the military to prevent corrosion. Nitrocellulose lacquer has been used to protect brass and copper from tarnishing. So how is the metal deteriorating in our knives? We have to understand there is a galvanic pecking order among metals. Molecules of Metals with higher potential want to naturally migrate to a lower potential, or stabilize. What you are witnessing is the same type of activity that occurs on a boat if it is not protected.

When we seal away our beautiful knives in their wrappings, cases and containers, we are creating a mini trapped atmosphere of the gas that is emitted from the the celluloid composition that serves as a plasticizer. Even all modern plastics have plasticizers in them to preserve shape, strength and prevent brittleness. They are relatively unstable, some more than others, and they give off gases as part of the process of plasticization. When the plasticizers have become exhausted, the remaining compounds become brittle. Ever roll up an old carpet, once soft and luxurious, that cracks and falls apart?

The gases created in these closed environments are like a mini ocean. They allow molecules to migrate between metals of different potentials. There is a pecking order in metals, the more susceptible metals migrate to the less susceptible. One of the most vulnerable and therefore most likely to be cannibalized in any group is Zinc. If you place zinc in your boat’s system, it becomes the sacrificial (anode) and protects the (cathode) your prop and engine drive. Within a season, the zinc will deteriorate away. In that way, think of our tightly wrapped up knives as being in their own little conductive gas ocean.

Worse, plasticizers have some solvent capabilities which is what makes them plasticizers. When these gases leave the celluloid handles, they’ve served their purpose and should quietly disappear. Trapping them in wrapping or closed containers can cause accelerated deterioration of the celluloid and harm fabrics, other plastics, leather, wood, etc.

My suggestion is to take all of the packaging, cases, etc., and store them somewhere for safe keeping. Put your collection in a well ventilated area, preferably on inert glass or stainless trays. If you keep them in drawers, leave them slightly open. For the extra precautious, you can use small gauge telephone wire with alligator clips to clip the metal frames or blades to a common chunk of zinc.

This explanation is different and apart from normal atmospheric corrosion which is an oxidation, like rust. But the cure might be similar. If you use pliers in salt water, sticking them in a ziplock bag is a recipe for disaster; rinsing and drying them, treating them with a water displacement spray and hanging on a pegboard is the right answer. You are likewise interrupting a corrosive natural system.

To conquer the enemy, we must first know who he is and understand him. I hope this helps.

[herbva]

Interesting theory but it fails to explain another facet of celluloid degradation: that of why a cover & brass liner on one side of a knife will be completely eaten away while the other side is like new. I have had 3 knives that this phenomenon has occured.
I still believe that petroleum products play a role in creating the onset of degradation.

Ray, I have also observed some knives that have been damaged only on one side by celluloid outgassing. I can't help but wondering if perhaps these were knives that were resting quietly on one side, minding their own business, and when the evil celluloid started to deteriorate, the corrosive gas rose straight upward, interacting only with the exposed top half of the knife.

[Jpdragons1]

Thank you for the feedback on the puzzling one side . Without knowing the specifics, one sided degradation could be the cause of degradation if the celluloid is treated with some sort petroleum lubricant which is carried by gravity to the lower half. Not sure I’m inclined to lean in that direction as a choice though. If a knife is tightly wrapped up, whether the off gasses are lighter or (possibly heavier) than air, they will pool on one side of a knife or the other inside a wrapping. That accelerated degradation actually may stabilize the unaffected side by attracting any of that side’s off gasses to the more active side. The galvanic activity, I believe, still explains cases of metal migration. The celluloid degradation is mostly a Co-occurrence along with galvanic activity. Eric offered a link to an incredible thesis on celluloid degradation. The physical, photochemical, chemical, and thermal causes are somewhat limited with the care given knife and music instrument collecting. The inactive atmospheric activity I think aids and abets degradation and acceleration and galvanic activity. The missing factor here is the quality of the celluloid production. Some examples exist in fine condition dating back from the dawn of celluloid production. It would be an interesting study to find the storage conditions leading to accelerated degradation. Nonetheless, one sided degradation is a perplexing puzzle.

[Sharpnshinyknives]

Always a topic of interest to me. I stopped worrying about celluloid outgassing by never buying a celluloid handled knife. But for those who still want to go down this road, this is great information. Could you address whether using brass or nickel silver pins and liners would help to mitigate the galvanic reaction you mentioned. I’ve seen on older knives how this galvanic effect works when you have two dissimilar metals on a knife. You see this corrosion a lot on the ricasso of knives where the metals of the blade and brass liners interact. You seem to have a good understanding of the subject so I would be interested in hearing your thoughts.

[Reverand]

I doubt that this has any bearing on what you are describing, but another aspect of outgassing that I have noticed is that thinner pieces of celluloid tend to be more stable than the thicker pieces.
As an example, on this George Schrade Presto that I bought to restore, you can see that the celluloid still looks good on all the parts where it is thin and hollowed out beneath, yet has deteriorated badly in all of the thick parts.
Celluloid wraps on shell-handles knives are another example - I have never heard of one of those outgassing.

[Paladin]

I just avoid them like the plague. There are plenty of beautiful knives out there so why put one of these time bombs in the mix.

Ray

[Jpdragons1]

Eric,

Thank you for the fantastic link. The production and degradation of celluloid are certainly complex. There is also a need to examine the interrelationship of dissimilar metals. Fascinating read, again thank you.

John

[knife7knut]

Another reason that sealing off the air from getting to the knife doesn't work is that nitrocellulose contains it's own oxygen molecule which would not only allow degradation to begin but would even allow it to burn without an outside atmosphere. Maybe storing them in an inert gas environment would help.

[beresman]

Another thing that should be taken into consideration is that nitrocellulose itself degrades over time and releases nitric acid. This does not require a galvanic action to attack just about any metal. So while this is an interesting idea, and may be a contributor to the degradation of our fancy knives, I don't think it's the whole story.

[ea42]

Eric,

Thank you for the fantastic link. The production and degradation of celluloid are certainly complex. There is also a need to examine the interrelationship of dissimilar metals. Fascinating read, again thank you.

John

My pleasure John! It's the best bit of research I've been able to find on the subject. One thing I've found is that celluloid seems to have no (or very little) effect in stainless steel blades. Of course that doesn't help much when the handles are crumbling around them. It seems like once the degradation starts it becomes a self feeding runaway train. Sealing them up or keeping them in confined spaces definitely seems to hasten the process, especially externally. I've seen far more damage to the surrounding bolsters, blades, and shields on knives in boxes, rolls, or worse, baggies, than I've seen on knives in the open. That might have something to do with the knives with damage to one side as well. If a knife is sitting on a surface that will hold moisture or trap the air around it, that side of the knife might degrade much more quickly than the side that's exposed to air.

Eric

[Jpdragons1]

Brent,

You make some very good considerations. The completed compounds in properly produced celluloid may begin their life as stable, but I imagine some set of conditions begins complicated chain reactions. In and of itself, I think nitric acid is a powerful oxidizer that can promote metal corrosion which often coincides with galvanic activity. If you were to treat a group of metals to acid oxidation, you would see it occur essentially in the pecking order of galvanic potential. A zinc boss degrades before a brass rivet before a steel liner. Metal migration and chemical degradation are coconspirators in a complicated ballet. Unfortunately it is an extremely slow process that is difficult to study with many variables. Imagine placing a knife in a sealed glass jar with iron oxide oxygen absorber pouches. Oxidation is essentially prevented by any acidic attack, but can the continuing emitting plasticizer gasses present enough of a of a conduit for galvanic activity to occur?

Of course I can only theorize on these complexities. But we do know enough about the behavior of metals in that they migrate better in in liquid or gaseous fluid systems. Improperly produced or stored celluloid may very well be a ticking time disaster no matter what we do. I suppose the real question is whether we can improve what is a long process by making it considerably longer?

Good thoughts,

John

[1967redrider]

I wonder if submerging a knife completely in mineral spirits would stall the process?

[Jpdragons1]

Always a topic of interest to me. I stopped worrying about celluloid outgassing by never buying a celluloid handled knife. But for those who still want to go down this road, this is great information. Could you address whether using brass or nickel silver pins and liners would help to mitigate the galvanic reaction you mentioned. I’ve seen on older knives how this galvanic effect works when you have two dissimilar metals on a knife. You see this corrosion a lot on the ricasso of knives where the metals of the blade and brass liners interact. You seem to have a good understanding of the subject so I would be interested in hearing your thoughts.

Hi Sharpnshiny!

This is an interesting question. Galvanic action can only take place in a system. Many of you in the New York, New Jersey, Pennsylvania area, have seen rock faces along roads covered with steel fencing to keep breakaway rocks from tumbling onto the roadway. If you look carefully you will notice large rings of zinc attached with cables along the run. This is cathodic protection, the cathode (steel) is being protected by the sacrificial anode (the zinc collar.) let’s say you have a G10 handle with an embossed zinc badge attached to the face with adhesive, no metal connection to the rest of the knife. Very unlikely to degrade. The metals and alloys need a pathway. Air can be that pathway, but in the case of our highway example, the humidity, rain, and ground dampness is far more harmful. If you are restoring a knife that has had this happen, there are precautions you could take to preserve the condition you worked for so hard. Rather than try to decipher the interplay of different metals, zinc is so low on the totem pole it is a safe bet. If it is worth the time, clock smiths live in this micro world. They could make for you bushings out of zinc to fit the holes perfectly. Then your rivets, pins, or screws go through these in tangs, liners, handles, locks, etc.,. If the clock smith makes you spares, you have just to look at the condition of these bushings for degradation, and replace them. The other metals would be spared. The problem with galvanic action is once the guy at the bottom is beaten up, it progresses up the chain to the last man standing. Although they use mostly brass, clock smiths make these same kind of bushings for clock plates to support wheel pivots. The smiths could be a valuable asset in your arsenal. Luckily, they are much easier to find in your part of the country.

Thanks for the question, hope this helps,

John

[Mumbleypeg]

Interesting discussion. The recommendation to store celluloid items in open air rather than an enclosed space is the one many of us have advocated for, just based on anecdotal evidence and experience.

To add some humor to the discussion: many languages assign gender to nouns. The English language doesn’t typically do that. But if it did, my opinion is “celluloid” is feminine. Beautiful, unpredictable, and when it goes off, look out!

Ken

[Paladin]

Interesting discussion. The recommendation to store celluloid items in open air rather than an enclosed space is the one many of us have advocated for, just based on anecdotal evidence and experience.

To add some humor to the discussion: many languages assign gender to nouns. The English language doesn’t typically do that. But if it did, my opinion is “celluloid” is feminine. Beautiful, unpredictable, and when it goes off, look out!

Ken

Good one, Ken!

Ray

[1967redrider]

I can upload pictures of a Winchester large Toothpick that I keep unboxed, blade open, in my living room. It has snapped the spring and liner. So even airflow isn't foolproof.

[Jpdragons1]

I wonder if submerging a knife completely in mineral spirits would stall the process?

I suppose the concept of denying oxygen intuitively makes sense by submerging in mineral oil. Mineral oil, however, is a highly refined petroleum distillate usually. I would be afraid of it degrading if not possibly reversing the formation of the celluloid through a chemical interaction. It might be possible with the right gas or gas mix. For example studies have proven irreparably rusted tools can be reversed by subjecting them to pure hydrogen under pressure. The hydrogen scavenges the oxygen out of the iron oxide leaving the remaining ferrous atoms to merge back into the substrate.

Stabilizing the celluloid would obviously be the gold standard solution.