Keep in mind that busy laboratory freezers are often crowded with storage boxes of samples and reagents – and that all of these are competing against ever thickening layers of ice. This is why a routine defrosting is important, as it gives you a chance to reclaim some space and organise whatever the freezer is currently housing. We have compiled some tips that will allow you to achieve this with minimal disruption and whilst keeping research on track.
- 1. Notify all lab workers
Because many samples a precious (hard to obtain and often impossible to replace), it is of the utmost importance that you alert everyone working in the laboratory to an upcoming freezer defrost. Notify everyone of where their samples will be temporarily stored and warn them that loose, unmarked tubes will be thrown away. Hold a meeting to discuss this, send out an email and post notices around the workplace.
- 2. Learn to love labels
Whilst you have everyone’s attention, this is also a good time to conduct some re-training in better lab practices. Require all employees to mark sample and reagent boxes with their name and the date it is being placed into the laboratory freezer. This is a great time to invest in a label maker, as the ink will be able to withstand the frost and the print will always be legible. You can also encourage people to cull old work.
- 3. Minimising freeze-thaw
The good news is that nearly all freezers will have a manual defrost feature, which keeps the temperatures more stable than automatically defrosting ones do. Every time someone opens and closes the door, warm air enters and forms condensation on the walls and coils, which leads to ice buildup. To help minimise this, now is the perfect time to set up a working refrigerator for frequently accessed samples.
- 4. Preparing for transfer
You will want to schedule the defrost when the lab is relatively quiet and defrosting overnight is not ideal (especially if you expect excessive water to be a problem). Make sure that all of the backup laboratory freezers are ready to receive the samples and reagents – if you are struggling to find room, use recycled foam shipping containers that have been loaded with ice. You can then proceed to transfer boxes.
- 5. Work from the top down
Once the shelves are empty, use squeegee bottles to squirt hot water onto the coils and wire racks (as these contain the heating elements). Mop around the area as the ice melts, cart the water to the sink for disposal and repeat all over again. Never chip away at the ice with a sharp implement, as you may actually damage the freezer. Once the defrost is over, bring it back to temperature and restock.
Make sure that you keep an eye on your laboratory freezer in the future – if you notice ice building up more quickly then usual, you should probably get the seals inspected, as a poor seal will allow outside air in. The final piece of advice that we can offer is to have a freezer alarm system installed and to establish an emergency plan for power outages or natural disasters, as all laboratory workers need to know how to proceed.