A common method of cleaning embedding molds involves putting them in the processor during the clean cycle. Though this method is effective, and pervasive, it may be discouraged by management or your vendor reps, concerned about the potential effect on the processor. Its common to hear that this method of cleaning is hard on the processor and paraffin from the molds can get clogged in the lines of the processor. These can be valid concerns, so if you’re going to keep putting your molds in the processor, change cleaning reagents more frequently to prevent wax buildup.
If you’re looking for an alternative method of cleaning, soaking them in a bucket of xylene and rinsing in alcohol is common. Or, you can put the molds in a metal container with water and detergent, put it over a hot plate and let it boil. Once it is cooled any left-over paraffin will collect at the top. Let it harden and then peel it off. Rinse the molds and let them dry. This method might be easier for a small, low-volume lab though, and may not be efficient in a larger lab.
Some labs simply melt off the paraffin and then use gauze to wipe the molds clean, then wash in hot water with detergent. Or, avoid the problem altogether and switch to disposable molds.
First posted on NSH’s “Fixation on Histology” Blog.