Guide
Toll drying and blending services
Updated
Toll drying turns your liquid or wet cake into a powder on someone else's dryer. The dryer type decides what the powder looks like, so it is the first question.
Talk to a specialist Who owns the materials, who carries the price risk, and the clauses to settle before a formulation leaves your building.
What toll drying covers
Drying is done in spray dryers, tray and oven dryers, rotary dryers and vacuum dryers, and each produces a different particle and treats heat-sensitive material differently. Ask which dryer a site would use for your material and why.
Ask for a trial on your material before a price is fixed, because drying rate and yield are only known by running it.
Toll drying and blending services together
Some sites dry and then blend the dried powder with other components in one campaign. That saves a transfer and the loss that comes with it, but ask where the blend is done and whether the powder is held between the two steps.
The powder blending guide covers what to qualify in the blending half.
Dust from a dryer
A dryer makes a fine powder, and OSHA notes that combustible material in finely divided form can become explosible when suspended in air. Ask how the site collects fines from the dryer exhaust and how it manages dust in the packing area.
Source: OSHA, Combustible dust (read 30 Oct 2026)
Yield is the number to agree
Drying loses material to the exhaust, to the walls of the dryer and to off-specification start-up product. Under a toll that loss is yours, so agree the yield allowance and moisture specification before the first run, then what to qualify in any blender.