Freeze - Thaw Stability in Amerimulch Colorants

Mulch colorant is water based (not oil or solvent based), which means that it will freeze at temperatures below 32^◦ F.  All Amerimulch colorants are categorized as being freeze-thaw stable.  That means most of the time our colorants can freeze and go back to a usable state after thawing and remixing.  However, in some cases additives and extensive remixing are required and the material still may not be recovered.  Here is a closer look at why.

A particularly troublesome problem arises when an aqueous dispersion is shipped or stored during the winter months and the dispersion is exposed to subfreezing temperatures.  Maintaining a suitable ambient temperature during shipping and storing requires special handling; it can be more expensive and is subject to human error (if a container of mulch colorant is left outside or in a building that drops below freezing). 

Generally it may be expected that when an otherwise stable dispersion is exposed to one or more freeze-thaw cycles, the dispersion will be "broken". This means that after the frozen dispersion is thawed, the particles will separate, sometimes irreversibly, from the aqueous medium. 

When the colorant is frozen, the ice phase that forms is essentially pure water. Since the chemical similarity between most dispersed particles and water is not very great, there is very little tendency for an ice crystal to incorporate a dispersed solid particle. Thus the freezing can be considered a dehydration process in which the water is removed from the dissolved or dispersed foreign substances as the water-to-ice conversion progresses.  It follows that when the water is melted, the particles that have joined together may precipitate from the dispersion in an irreversible manner.

Because of this, we recommend storing your colorant in a location that will prevent it from freezing in order to avoid the difficult and time consuming task of trying to recover frozen colorant to a usable state.  

If colorant does freeze, it must be allowed to thaw completely.  At this time, multiple additives can be added that, along with thorough mixing, may bring the color back to a usable state.  Freeze-thaw cycles reduce the stability of the colorant and will eventually cause a hard pack condition resulting in unusable material - a situation to avoid.  Contact Amerimulch or your sales rep for additive options at 888-556-3304.