Buckets used for glycerining should be kept clean. The high cost of glycerol means that the solution must be re-used several times. Thus, a biocide should be included in the solution to suppress pathogens. Copper catalyses the decomposition of bleach and should be excluded from bleaching solutions. Organic fungicides such as Benlate should not be added to the glycerining solution because they are not water soluble and may clog stems.
Acid dyes are incompatible with most of the above biocides.
The glycols are more expensive and may be difficult to obtain. Sorbitol is the cheapest of the readily available liquid humectants. Some quaternary ammonium salts show promise as humectants. However, data on their water holding capacity is not available. Because it is the water that the humectant 'binds' which provides much of the plasticising effect on the foliage, relatively less humectant can be used for a market where the humidity is high.