Below, find an array of pointers when using the CryoCaddy and associated elements.
Using a gel film in the mold base is not always necessary as most tissue is naturally sticky and will adhere to the plastic, even when the mold is inverted. However having the gel film freeze and anchor the specimen in place is very useful for small biopsies that may otherwise be displaced by the weight of the gel overfill.
Room Temperature Chucks
It can not be over emphasized, the importance that room temperature chucks have to the achieving the accuracy of the CryoCaddy frozen section embedding technique. When a room temperature chuck is joined to a mold the gel that is still fluid will allow the chuck to fully settle against the mold shoulders so the block face will be perfectly parallel to the chuck. A cold chuck will cool the gel creating a loss of viscosity which will prevent full and exact settling of the chuck. The result will be a block face which is slightly skewed, requiring additional, unnecessary, trimming in.
When freezing at -78C, using a room temperature chuck has no appreciable effect on freezing times.
When the top is off the caddy the freezing platform will condense any moisture in the air which will build up as frost on the block. This frost acts as a very effective insulator and needs to be scraped, brushed or wiped off the working (contact) surface before freezing.
The edge of a mold makes a handy little scraper.
Warming Up Super Cooled Chucks
Chucks should not be left on the freezing platform any longer than necessary, even when chucks are transferred to the cryostat chamber in a timely manner the tissue will be too cold to cut and will need about 30 seconds to come up to cryostat cutting temperature.
Because the cryoblock is condensing moisture from the air, and even though the freezing platform is being scraped a layer of clear ice will eventually form which will noticeably slow down freezing and may clog the chuck post holes. To avoid the buildup of this ice the cryoblock needs to be thawed out every now and then.
Thawing can be done with warm water or by just leaving the cryoblock out over the weekend.