Catalin Plastic

What makes Catalin plastic oxidize from white to yellow/dark orange? Air, sun light, dirt, oil from human hands I have read about as much as I can find, but nothing on what really causes it.

So just leaving Catalin plastic on a shelf somewhere should do it with some time. How do your posts keep ending up in mine?

Smjprogrammer wrote:So just leaving Catalin plastic on a shelf somewhere should do it with some time. How do your posts keep ending up in mine?

LOL, I keep hitting edit instead of quote. I have a habit of doing that.



Previous reply:

You are right, its the oxygen rich environment that causes it to turn yellow. Due to oxidation, older Catalin items darken in color with white fading to yellow. In an oxygen free environment, the Catalin would most likely stay white. Seth

Any guess as to how oxygen rich an environment needs to be, and for how long until some yellowing appears?

If it is "real" Catalin, UV light will speed the yellowing process. Oxygen has some effect but not as
much as UV.

wvh1946 wrote:If it is "real" Catalin, UV light will speed the yellowing process. Oxygen has some effect but not as
much as UV.

Yep, that makes sense. I like the use of the word "real". A lot of the stuff I hear people calling Catalin, is not always catalin. I often hear Catalin being called, "bakelite, lucite, celluloid, and catalin." And sometimes other names. Seth

So if I leave some Catalin plastic in the window for a couple of years it should darken a bit.

If it's UV light that does the trick, you could try finding a friendly dentist or some other professional who use UV lights. The concentrated beam should work much faster. (they use UV to cure resins in a rush.)

Could I ask why you want to "age" Catalin?

Are you replacing mount on a set of pipes with a "vintage" item and want to color match it to
what's on the pipes? For instance, the mounts on the pipe have gone dark orange but the
replacement is yellow?

If you are replacing a mount, most likely the "vintage" replacement part will remain yellow even if
you use a UV light source. "Vintage" Catalin turned color differently from batch to batch.

And as Seth said, there's a lot of resins today that are refered to as Catalin. If you are replacing
a mount and have purchased one made recently, most likely it is acetal polymer. UV won't have
any phototropic effect on it.

I have a set of 1950's Hendersons that have gone "pumpkin" and a set of Dubars. I'd love to age
the Dunbar mounts to match but sadly they're mounted with Delrin. Stuck with white for the ages!

Smjprogrammer wrote:So if I leave some Catalin plastic in the window for a couple of years it should darken a bit.

Can you post some pictures of what your working with so we can get a better idea as to what you have. Seth

I have two R.G Hardie pipe chanters I am no longer using the one in the picture. I will be keeping it along with the one I am using. I have had the solo off for weeks now, and just thought now would be a great time to figure these things out. My set is about 1970-1975 ish.

Sorry for being late but I've been off the net for a while...
Oxygen on its own won't do, UV is also needed. I have tried treating catalin with pure oxygen/hydrogen peroxide as well as ozone, at no noticeable effect.
The catalin only yellows at its very surface, therefore you will have to finish the piece first before exposing it to light and air.
Heat also plays a role in the darkening, I've had good results using a sterilizing oven, 90 minutes at 140°C gave the same orange colour matching the mounts of my ca. 1930 set of Crowley pipes (some of which had to be replaced).
Wear respiratory protection when working with catalin, as formaldehyde will evaporate. Of course, good air circulation is essential or you will have the smell all over the house. If it doesn't stink like hell, it' not the real stuff.

Why did some of the Catalin need to be replaced? Was it because of the sterilizing oven or old age? Also when I rub this stuff I deafeningly get a smell off of it unlike other plastics.

What I meant to say is - some of the original mounts were badly cracked or partly missing, so I had to replace them. I then used the sterilizing oven to make them look like the original ones (except of the dirt of the decades, which only time can provide).

Did some research on Sterilizing Oven’s, and if I am correct they are called Autoclaves. I am under the impression that a Stovetop Autoclave could melt some plastics. Whereas an Oven Autoclave uses dry heat there for would not melt the plastic. However I read somewhere that Catalin plastic is pretty heat resistant to begin with, so maybe both could do the trick. That is if I had one or the other.

An Autoclave works with heat, steam and pressure, whereas a normal sterilizing oven works with heat only (these names might be used differently in English language, I'm not sure).
The normal sterilizing oven is basically a device which can be set to an exact temperature for a certain amount of time.
I'm not sure if catalin does melt at all, but if it gets too hot, the surface will develop cracks.
I guess an ordinary baking oven will do the very same, provided the temperature setting is exact and does not exceed 140°C.

Where did you get this Sterilizing Oven?

I needed it when I was a naturopath, practicing alternative medicine.
No use buying one, they're not cheap. Ask a friendly doctor if you can use his for an hour and a half.
BTW, they are also called "dry heat sterilizers".

Today I experimented with an extra Catalin drone ferrule on my lathe. I took some microfiber cloth and used it to warm up the Catalin. I could see it get darker before my eyes. Problem is the unevenness and if you do it wrong it will take it right blackout. Would it be a better idea to use some kind of plastic polishing cloth?

I tried the same - doesn't work.
The unevenness is one problem, spoiling the surface (which seems to happen invariably) is the other.

I've been down this road before in restoring old radios with Catalin cabinets that started life as
white, turned yellow and were missing items like bezels or knobs. Finding replacements was hard.
Aging them darker or trying to lighten the replacements to match the base cabinet was
impossible. Trying to match the color by accelerating the process usually winds up with ruined
parts.

If it will fit, why not swap soles? Put the matching sole on the chanter you're playing now
and the off-color sole on the one you won't be playing.

Today I used a cotton wheel and some liquid brown shoe polish on some Catalin. It makes it darker quite fast, and gives off a nice shiny gloss with a sturdy feel. As I suspected it wipes off with rubbing alcohol, but it took a little time. After it is off it looks a bit dull. Is there a way to keep it on permanently? Also I was reading on a guitar forum that Halide lamps can darken Catalin within a month. Is it true, and why would that be?

I just recently purchased a heat gun to see if I could get Bakelite/Catalin to turn burnt orange. It works better than anything else I have tried so far. Just put the piece in question on the lathe. Aim the gun carefully at the plastic with a close range. It will turn dark within minutes. Doing this ruins the nearby finish by oozing oil/tar from the Blackwood right through the lacquer. So be prepared to do a little refinishing afterwards.

However, I also found this to be quite useful in removing any mounts. I only have one word of advice if you do get a mount off. Keep it off until you have cleaned all glue from both pieces before putting it back on. Otherwise, it will be stuck. The heat seems to reactivate the glue to its true strength extra stubborn.

Happy Darkening