I am trying to find a chart on how many desiccants per quart jar is needed. Something like if the humidity is 50% and the size of jar is 1 quart, you need X number of desiccants in the jar. I want to vacuum pack dehydrated strawberries, etc. to enjoy in the winter. As far as I can find, there are lots of people willing to say they add 1 desiccant per jar, 2 per jar, etc. But I am looking for something where the results have been verified.
I will be using canning jars not Mylar bags due to rodents and ease of re-usability.
If the container you need to protect is 950cc or less in volume, a gram-size desiccant requirement chart is available here.
We also have a calculator which will give an estimate of the number of units of Clay or Silica Gel desiccant required for any size Moisture Barrier Bag. Desiccant Estimator
The amount of desiccant/adsorbent required will depend upon the chemical characteristics of the product as well as the volume contents and physical properties of the container. We recommend a stability study be performed to determine exact amounts required. Samples available upon request."
The colour usually shown by silica gel is due to an indicator, added to see directly when it is dehydrated and when it has
absorbed moisture. For many years, cobalt chloride (Cl2Co) has been used. This substance gives the dehydrated gel a
strong blue colour and a pale pink colour to the gel having absorbed moisture. Recently, the European Union banned
its use because of considering it carcinogen through inhalation. A search for new alternatives led to some iron salts,
where the change in colour can be poorly distinguished. At present, the most advisable alternative is methyl violet,
which gives the dehydrated gel an orange colour and a green colour to the hydrated gel.
The methyl violet product is available from Southern Exposure Seed Exchange. They have announced that they will discontinue selling this product once their supply runs out.
EDITED to delete obsolete link (no longer functional).