Does Hydrocal "expire"

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N

nsconductor

Member
Just wondering if Hydrocal has a shelf life? I found a carton 3/4 full that I have had for about 8 years. If was left in a old house where my last layout was being built. Nobody lives there and and it has been sitting in that house throughout the seasons, and temp changes. It was sealed up and I shook it before use and it came out in it's regular dusty powder form. However, I mixed a small batch per the instructions on the carton 1 and 1/4 cup of Hydrocal to 1/2 cup water. I used that to fill up one of the large rock moulds from Woodland Senics about 8:30pm last night. Checked it again at 9:30pm, still gel-like.... Figured I'd let it sit over night, checked it at 10:30am this morning and still gel-like....but slightly less than last night. Seems like this stuff dried in about an hour last time I used it years ago....but 14 hours later and it's nowhere near dry..... wonder if it has gone bad.
 


Plaster of Paris & Patching Plaster & anything else in Powder form will expire w/age, humidty, cold & heat. In my building where it gets real hot in the summer & real cold in the winter a bag of Patching Plaster only lasts for about 6 months.
 
I just used some lightweight hydrocal that has been in my basement for about 4-5 years. It worked fine but we have a dry basement.
 
I have kept my unused Plaster of Paris and Hydrocal in wax-covered cartons for years. Whenever I go to use it, it's fine. I also control my basement's humidity, but temps vary because I heat in the winter with a wood furnace that is just inches from my layout. My basement can get uncomfortably hot, but never rises above 60 % humidity for more than a day or two before I notice what the humidistat says and crank up my de-humidifier.

Crandell
 
It would seem that Hydrocal doesn't have a shelf life if stored in a dry place. I bought a 50# bag about 25 years ago, and still have about half of it left. I do a stint of rock molding about once a year at about this time. It still performs the same now, as it did when I bought it. I took no special care in storing it, except to tape the bag shut after use. It's been stored in my shop, and in my basement, both locations are dry, and at a fairly constant temperature.
 
OK landing said:
It would seem that Hydrocal doesn't have a shelf life if stored in a dry place. I bought a 50# bag about 25 years ago, and still have about half of it left. I do a stint of rock molding about once a year at about this time. It still performs the same now, as it did when I bought it. I took no special care in storing it, except to tape the bag shut after use. It's been stored in my shop, and in my basement, both locations are dry, and at a fairly constant temperature.
Click to expand...

Hydrocals biggest enemy is moisture from high humidity. I did what OKlanding did only it was 30 years ago. I broke down the 50# bag into plastic 5 gallon buckets with plastic snap on lids and some 1# and 3# coffee cans with snap on lids. It has been stored under the layout in my basement for all that time. Still using the hydrocal with no problems just like he is. As the larger containers get used up I transfer the remaining amount to smaller containers to keep the air space to a minimum.
 


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