Is it waxed or some other treatment?
I had a waxed jacket go like that, I hosed it down with warm water untill it soaked through, then re-proof with Nikwax cotton proofing. That worked.
To the tune of "Mademoiselle from Armentières"
Napoleons army ran away, As you do
The guard stood firm for Frances Pride, As you do
They said the guard will stand and die
But we heard what their Colonel cried
It wasn't pretty I tell you.
Resistance is fertile
That's the Belgian smock? Mine has a plastic interliner that covers the shoulders (can't remember if it goes down the sleeves or not) that is distinctly crackly now but still very wearable and it has never seen a washing machine. I seem to remember Barrie put his straight in the wash when he bought his two and they came out completely unwearable! I guess the detergent or hot water does something to the old plastic - perhaps its some sort of celluloid.
I think the warm water/detergent degrades the old plastic liner. Barrie chucked his two I think - I have no idea how you can un-harden plastic and would guess it is irreversible. Best best it to beat it into submission (or perhaps wear it for a week) and hope it starts behaving!
That's the Belgian smock? Mine has a plastic interliner that covers the shoulders (can't remember if it goes down the sleeves or not) that is distinctly crackly now but still very wearable and it has never seen a washing machine. I seem to remember Barrie put his straight in the wash when he bought his two and they came out completely unwearable! I guess the detergent or hot water does something to the old plastic - perhaps its some sort of celluloid.
Plastic and heat often do not mix, even low heat, and it is the same with some chemicals. I remember getting a donkey jacket cleaned many moons ago and was advised by the dry cleaners that it could come back unusable if the shoudler panels were a certain type of plastic (it didn't). Once plastic goes, it is gone! Prevention is the only option but even if it is sealed from the air and away from light, you are fighting time. Example: many old airfix figures now are brittle and hard, and smell of sick, because the plastic has degraded, no fix has yet been found but exposure to air, leeching of fixative or UV light damage (the same that yellows old white plastic) have all been blamed. As this seems to be almost exclusively Airfix figures, the type of plastic seems to be at fault, as not all airfix figures of the same age are effected, it may be poor quality control of the plastic mix.
Wax on the otherhand can harden but can be rejuvinated though most involve using flammable liquids (parafin, self evident, but boiled linseed oil seems safe but can spontaniously combust as it dried out) so washing out and re-proofing is the safest option.
If no plastic or wax is involved, what about fabric conditioner to relax the fibers? Yes a good beating might do it (after all it works with tight weave woollen blankets).
To the tune of "Mademoiselle from Armentières"
Napoleons army ran away, As you do
The guard stood firm for Frances Pride, As you do
They said the guard will stand and die
But we heard what their Colonel cried
It wasn't pretty I tell you.
Resistance is fertile