There are three ways that spotting can occur:
- If there is soil introduced with the rinse (ie: contaminants in the DI bath),
- If soil is introduced in the air stream (ie: either present in the atmosphere and blown onto the parts or circulated from the air supply into the heater and blown onto the parts), or
- If soil is left as residue from the wash process (this could either be soil that was originally on the parts and not completely washed off or it could be residue from the cleaning chemistry that is not completely rinsed off).