Multiple Stage Cleaning

Multiple Stage Cleaning Reduces New Solvent Purchases & Saves Money

Let your dirty solvent do your dirty work. That’s the principle behind multiple-stage cleaning. Whether you are cleaning printing presses or automotive parts, multiple-stage cleaning can reduce your costs for solvent purchases and disposal.

When one container of solvent is used for cleaning, the solvent becomes dirty with the soils that it removes from the parts, decreasing its ability to clean well. With multiple-stage cleaning, dirty solvent removes most of the soil, while the clean solvent of the additional stages thoroughly cleans the parts and brings them to specification.

Solvent use decreases because the solvent is used longer before it is discarded. When only given a cursory look, multiple-stage cleaning appears to use more solvent. Not so. While you need extra containers of solvent for the added cleaning steps, all the solvent lasts much longer than it would if used in a single cleaning step.

Using multiple-stage cleaning can also making drying times more consistent. After the dirty cleaning of the first stage, the cleaner solvent in the later stages evaporates at a consistent rate.

Determine the number of stages that work best for your operation. Often only two or three stages are appropriate. Multiple-stage cleaning can be accomplished with flushing, immersion, sprays or a combination of these. The first stage can be used as a presoak.

A three-stage cleaning process works like this:

  1. Majority of the soil is removed using dirty solvent.
  2. Soil, left after the first stage, is removed using partially dirty solvent.
  3. Any remaining soil is removed by the cleanest solvent.

Industry Example

When the solvent in the stage-1 container becomes too dirty, empty it. Refill the container with the solvent from the subsequent stage; for example, the solvent from stage 2 becomes stage-1 solvent. Refill stage 3 with fresh solvent.

Anagram, a flexographic printer, used one bucket of solvent to flush unused ink from the printing decks. With the help of a MnTAP intern, they developed a three-stage cleaning process for their printing presses.

Using all three stages takes them an extra four to six minutes per deck. Often using only their first two stages is sufficient.

Savings: $28,200 per year through reduced solvent purchases and disposal costs. Reduces solvent waste by almost 120 drums per year.

This article was originally published in the 1997 Winter issue of the Source.