Casein - An Early Plastic

As I was cleaning my first group of buttons, I started discovering different materials. At the beginning I expected all the buttons to be simply made of plastic. I had no idea they could be any different. Of course, I could tell some were made of metal or mother of pearl, but the rest was just plastic to me.

These buttons smelled suspicious to me...

But then, some buttons looked different. They were lighter or made a different sound when put together in a bag. Some others had uneven surface on the back. I started researching and I learnt that there are lots of other materials in the plastic family, actually, most are early kinds of plastic, which have different properties. And thanks to this information, it is also easier to date the items as made in different decades of the 20th century.

CASEIN, or galaltih

is an early plastic, made of milk protein. Something organic and natural turned into plastic. Unfortunately not very durable. It was very popular from 1930s to 1950s, when it was replaced by more durable acrylic plastic. In Spain, casein buttons could be found even in 1960s, as the imposed embargo on foreign products made it difficult for the new technologies to get there initially.

A lot with casein buttons. These have embossed art deco pattern. 

How to tell whether it is casein or not 

To determine whether a button is made of casein, I use a damp cloth on it, leaving a bit of water to dry on the surface. While it is still a bit humid, I smell it. It usually gives out the scent of cured cheese, something very common in Spain. While smelling buttons are not the most pleasant thing in the world, I can assure you that when dry, these buttons look almost as if made of modern conventional plastic.

Another way of checking what the buttons are made of is by rubbing them vigorously. The smell is similar to when dampened, but not all casein buttons will pass this test. I personally have some buttons, which did not smell unless dampened.

There are beautiful marbled versions of casein, but also plain colours. I have embossed buttons and carved ones, small and extra large, flat and shank buttons, and some casein buckles as well.

Extra large buttons made of marbled casein. These are embossed rather than carved. These are from 1950s-1960s.

A vintage buckle made of 3 layers of casein, plain colour and with carved details. Fantastic example from art deco era!

How to handle casein items

Casein is extremely vulnerable to temperature and humidity. It should not be machine washed. Remember the old habit of removing buttons before washing a coat or a jacket? I guess it all made sense, taking into account that casein could easily be dissolved in water at a temperature higher than 50º C. Exposing it to water at whatever temperature is not a good idea either. A bit of damp cloth hasn't done any harm to them, not a quick rinse, but I would be extremely cautious when exposing it to water for any longer.

Click to see the picture in original size and you will see the cracked surface. These casein buttons have been machine washed. 

Apparently, however, casein buttons can withstand dry cleaning and ironing. The question is how much you trust your dry cleaner to follow the right procedure. There is still a risk that casein buckles or buttons may be mechanically damaged during dry cleaning. It is recommendable thus that you wrap them previously in something soft to protect against any chipping or braking. This should be done by the dry cleaner's, but I do not know any business around that does it.


If you want to see more casein buttons, just click HERE.