It does not matter if you are purchasing in bulk or pre-packaged, dental gypsums need to be stored correctly for best use. However, what is the best storage and is it possible?
Dental gypsum is not a stable product, meaning that its chemical balance is interrupted during the manufacturing process. Some of the water, which exists as part of its normal state is removed. It wants that water back and it will take it from wherever it can. We hope that it gets it back from a technician, clinician or clinical staff using proper water/powder ratios.
The best storage possible would be in a sealed environment with a humidity level of 0% and a temperature of 70ºF (21.1ºC). However, most of us do not have this type of environment in which to store this type of material. So living in the real world, what can we do?
We know that humidity and temperature change seasonally and, in fact, daily in most areas of the world. You should monitor these parameters to ensure the best performance of your gypsum materials. Here is our recommendation for the optimal storage technique.
- Store in a dry and cool place. Store in a place where the humidity is under 30% and the temperature is less than 72º F (22.2ºC). This includes dealer storage. If you cannot store as recommended, then be certain to recognize that humidity may cause a problem for you.
- Make sure that the date on the box or bag is less than two years old. Lot number shows the date as the 4th through 7th numbers of a 9 digit number. Example: XXX0317XX. (March, 2017)
- Keep the plastic liner closed and wrapped tightly when not in use or transfer bulk material to smaller, sealed lid containers.
- Stone or plaster bins: place only the amount used in a day and reload for the next day’s use.
- Use sealed containers in dental offices especially. Do not store opened powder in drawers.
If you do have a humidity problem with gypsum materials, it can manifest itself in clumping in the original box and/or by increasing the setting speed and decreasing the working time. It does not leave the Whip Mix manufacturing facility in this condition. This does not, however, eliminate using the material, nor does it eliminate the entire lot number. You will need to adjust the recommended water/powder ratio, (contact Technical Support for recommendations) and break up the clumps before adding the water. Breaking the clumps may be done by hand or by placing the clumped material in a dry bowl and using a power mixer without vacuum. Simply run the unit until the clumps are gone. Then you may add the water and mix using the normal ratio, but you should expect a change in working time speed.