I salute decitions of going for cold storage solutions, probably the only serious choice when storing colour material, for example.
But risky mesures needs strong reponse capacity. Before starting you should have concrete answers for questions like: how many decades your institution will be able to maintain the cold storage facility? What will happend if freezer stops working or power went off? have you power supplies and/or freezers available in very few hours to recover control of the situation?
When we don’t have economical resources to maintain a RH controled freezer and we choose a regular one, we must compensate the lack of money ressources with an equivalent amount of human ressouces. The control and the reponse capacity must be a lot intense since we’re putting our material in a very extreme situation and some hours of difference can damage it a lot more than several decades of doing nothing.
Once again, when going into details like the external (to the object, not the environment) RH at the moment of sealing, the importance of the interleaving paper is capital. Its capacity of contain and balance RH inside the envelope will depend of its caracteristics and also in their internal RH at that moment. We must realise that a 50% of RH a 20ºC (sorry, I don’t use fanrenheit often) will be more like 90% at 10ºC, so imagine the amount of water if you go into 1ºC… That’s why interleaving with neutral higroscopic materials become so important.
Just some toughts.