Ever noticed the spotting that occurs after prolonged storage in poor conditions? Worse still if the FDCs are put together in a stack (like some stamp dealers), some of the mould from the stamp will create a yellowing mark on the FDC next to it!! There goes the value of the FDCs. Think about all the hard wordk to queue, bid and hunt for the FDC to see it degenerate by moulding!
You can see samples of poor protection in a liquidation I am handling for a collector from Penang for his collection of first day covers from 1984 – 1989. They were really good covers with even the nice Penang Bridge cancellation. However due to his novice days, the covers were not sealed up and some were stacked together. I can only try to sell at less than 50 % of catalogue. This is considering the cost price plus the overheads to make the covers, I think he still loose quite a bit.
I keep the FDCs away from heat and moisture. In addition, I seal the covers up in Oriented Polypropylene (OPP) plastic sealable bags. It was all fine an dandy until the large and odd shaped sizes came into the market! I faced a challenge to find the larger OPPs for my FDCs.
Over the years I tried different types and share with my friends. When I branched out to other countries, I needed larger sizes (think United Kingdom, New Zealand!!) too.
As a guide here are some neat sizes to use:
Regular FDCs from Malaysia, Singapore, Brunei, Thailand, Indonesia, Vietnam, China, Taiwan, Hong Kong, Macau, Korea and Australia can fit into 114 mm by 241 mm OPPs.
Larger FDCs from Malaysia, United Kingdom, New Zealand can fit snugly into 152 mm by 216 mm OPPs.
Really large ones can generally fit into 241 mm by 368 mm OPPs. This is also generally good for full sheets.