Any Chemists In The House? Need Your Advice.

March 16, 2020

Hello everyone.

In follow-up to the topic of protecting ebonite and celluloid (cellulose nitrate) started in this thread:

https://www.fountainpennetwork.com/forum/topic/332509-experiments-to-re-blacken-hard-rubber/page-2?do=findComment&comment=4301019

I've been going down the rabbit hole of researching HALS and other chemicals that offer protection against UV light-induced oxidation. Something that would act as a moisture barrier would be nice as well. HALS and related chemicals can ostensibly be purchased, but the myriad variations and solubilities have me baffled. I found a resource on conservation of paintings

https://www.conservation-wiki.com/wiki/VII._Additives

but it doesn't really answer my question: what would be safe to use on a vulcanite and/or celluloid pen that would protect it from UV light and water, and can I apply it safely to these surfaces?

Any help would be appreciated.

And please be gentle - biochemistry was my major in college but that was decades ago.

Nick

March 17, 2020

Not a chemist, but I am good at research.

What you are asking about has been worked on for a hundred years regarding rubber, literally there are magazine articles from 100 years ago on this subject and products have been developed for that purpose. It is possible that you can get them at your local hardware store, or they can order them. Ask about 303 products in the automotive section. What you are looking for is a rubber, vinyl and plastic protecterant. It will be in a spray bottle and will dry on. Typically it is used to protect tires from damage due to uv, a problem for people living in the Southwest as tires there can degrade due to oxidation from just sitting in the sun, sometimes causing tire failure before they wear out.

Now, in regard to celluloid, I haven't found anything yet sold for it.

Edited March 17, 2020 by Parker51

March 17, 2020

Thank you Parker51. They are not commonly used/recommended for pens. I wonder why.

Does anyone have any experience with HALS?

March 17, 2020

For HALS to protect your material, they would have to be incorporated (dissolved) in the actual polymer. They won't help anything when only applied to the surface. The reason is that they catch and deactivate free radicals formed by UV light rather than absorbing the UV light itself. And it's not clear if they would work in celluloid either.

Hope the explanation is simple enough to be helpful.

March 18, 2020

Thank you Parker51. They are not commonly used/recommended for pens. I wonder why.

Does anyone have any experience with HALS?

You are the first person I am familiar with who has expressed an interest in preventing oxidation in regard to hard rubber pens. Typically the issues regarding them are related to restoration. The product I referenced does not restore the color or finish of a hard rubber pen.

There are only a few makers of hard rubber pens today and they largely have not had significant changes in appearance. The one I know that has had this problem has addressed this as a warranty issue.

I have a few modern hard rubber pens that I am thinking of using a preventative on, but honestly, as they are stored much of the time away from light and they are not made of the kind of hard rubber that has been noted to change significantly due to sunlight, it may not be worth the time and cost for me to treat them with a sun protecterant. In retrospect, it would have helped with avoiding discoloration with a hard rubber pencil I have as it has changed over the last twenty years or so, but at the time I didn't know about the problem as a relative newby then.

Edited March 18, 2020 by Parker51

March 18, 2020

Parker, I'm referring to vintage pens to prevent (further) deterioration.

OMASsimo, thank you for the simple explanation. I get what you're saying.

However, in this reference, conservation experts are talking about adding HALS to varnishes they use to protect old paintings. Have a look if you have a moment and let me know what you think.

https://www.conservation-wiki.com/wiki/VII._Additives

Thank you.

Nick

Edited March 18, 2020 by Dr.X

March 18, 2020

I quickly checked the article, which is interesting, indeed. But the HALS are only used to stabilize the damar or mastix varnish itself, which is prone to yellowing. That's the protective layer applied on top of a painting which skilled restorers can remove and renew. Photochemical reaction in the layer below are not affected by the HALS mixed into the varnish.