Heavy trays, towels and moisture: Part 1

May 24, 2022


 “On our heavy pans (e.g., total pans), we have always placed a surgical towel under them for protection and to reduce wetness in the trays. The linen company that we order towels from cannot guarantee lint free towels. What should we be using under heavy trays for moisture? We also noticed stains on the towels. Why is that?”


This is a great question concerning tray liners. My experience has shown me there are many reasons for using a tray liner within/outside of a surgical tray or on a sterilization cart. They are for protecting instruments or reducing wetness in a tray. This will be a two-part series addressing how to solve moisture management and surgical towel issues in June, and we’ll focus on staining problems found on the towels in July.

Medical device reprocessing staff use many different products as liners both for trays and sterilization racks/carts, such as a) laundered surgical huck towels used to wipe hands (e.g., white, green, blue, etc.), b) blankets, c) sterilization wrap cut to size, d) sterile purchase huck towels (reopened and used as liners), e) foam products, f) cellulose-based products, and other products.

Reasons I have seen for placement of these products are as follows:

  • Liner inside a tray
    • Protect the instruments in the tray since the weave in the surgical trays can cause pointed or sharp instruments to get caught and cause possible damage.
    • Solve a wetness (pool of water or some amount of water) found in a tray after sterilization has taken place.
  • Under a tray
    • Provide a padding (cushion) between the wrap and the tray.
    • Reduce tearing because of friction of movement of the tray.
    • Help solve wetness found in the tray after sterilization.
  • Sterilization cart/rack
    • Reduce tearing of wrap (act as a buffer or protection between the tray and the rack/cart).
    • Help with dispersion of excess moisture caused during the sterilization cycle.

In my view, these are some of the factors; and I understand there are others, but I am going to address these specifically.

How do we solve wet pack issues (moisture management)?

AAMI ST79 has many sections and annexes that go into detail on understanding moisture management, loading sterilizers, and other guidance for tearing and moisture issues.

  • “Annex O” has a helpful check list dealing with moisture management.
  • “Section 8.2” talks about the use of tray liners: “…Tray liners designed and intended for sterilization may be used to protect instruments from damage and/or absorb moisture… absorbent tray liners can absorb condensation and reduce the incidents of wet packs…”1
  • “Section 10.1” talks about:
    • Loading the sterilizer and use of liners: “...Cart shelf liners that have been validated for this purpose may be used and should be made of a non-linting, absorbent material that will dry in the drying time selected for the rest of the load. Follow the liner manufacturer’s written IFU for use and replacement instructions. … non-linting, absorbent cart shelf liners can be helpful in drying a load. Non-linting materials are recommended because lint can be introduced into a patient’s wound and cause a foreign-body reaction”1
    • Positioning of items on the sterilizer cart and how it can cause issues: “Placing metal items above textile items should be avoided…. placing metal items below textile items enables condensate to drain out without wetting other items in the load…”1
  • “Section 10.1.2” talks about Paper-plastic pouches: “… Paper-plastic pouches should stand on edge in relation to the cart or shelf, with the paper side of one pouch next to the plastic side of the next pouch. Holding racks or baskets specifically designed for paper-plastic pouches may be used. . . .”1

The role of loading a sterilizer (and how those items are positioned within the load) is very important. In the November/December 2013 publication of Pharmaceutical Engineering, they stated the following:

“. . . As a result, wet or damp items are observed at the end of the cycle. Wrapped items positioned so that condensate is allowed to collect will not be dried. Items should be positioned so that the condensate is allowed to flow downward. Items (wrappers, pouches, filters, or other porous biological barriers) that remain wet at the end of cycle cannot prevent contamination of the load when removed from the sterilizer. As the load cools outside the sterilizer, the water in the wrapper will be drawn into the wrapped item. Any contamination that is present in the environment can be drawn through the sterile barrier along with the water. There are numerous other possible causes for wet loads. The most common are:

“a. Insufficient drying vacuum level or time programmed.

“b. Rubber or plastic items in pouches (i.e., rubber stoppers, plastic tubing) may require additional drying (a pulsed air or heated pulsed-air drying process is recommended for these items).

“c. Wet steam.

“While there is no single solution to eliminating wet loads, it’s likely that experimenting with drying time, repositioning items, reducing load density, modifying cycle settings, and investigating steam quality will resolve the problem….”2

As the old saying goes, “Look at everything as though you were seeing it for the first and the last time.”

Should or could we (re)use surgical towels as tray liners?

Ultimately, surgical towels are meant for wiping hands and not intended for lining surgical trays. A surgical towel is a piece of linen capable of producing unwanted lint, and it should have documentation that it has been inspected for particles like hair and gone through a de-linting process. Also, most surgical towels are colored (e.g., green or blue) and can hide stains or issues with the sterilization process. Using a liner that is white can help when issues arise with steam quality. Thus, my advice is, whatever you use to line your surgical trays, whether it’s for protection or reducing wetness, make sure the IFU states it can be used that way. 

June’s moisture management and surgical towel issues have been resolved, but what about staining? Find out next month.

1. AAMI. (2017). ANSI/AAMI ST79:2017. Association for the Advancement of Medical Instrumentation (AAMI).
2. Dion, M. & Parker, W. (2013, November/December). Steam Sterilization Principles. Pharmaceutical Engineering, n.p.