Steam, Solvents and Stains
Understanding What Happens At Each Stage Of The Dry Cleaning Process

Most customers see dry cleaning as a black box. Garments disappear into a machine, then return looking better. For cleaners, what happens inside that machine determines everything from cleaning quality and stain removal to solvent cost and production speed.

This article walks through each stage of the dry cleaning cycle and explains what is really happening inside the wheel.

1. The Wash Cycle: Where Cleaning Really Begins

In dry cleaning, the wash step takes place inside the machine basket using solvent instead of water. The solvent is designed to dissolve “dryside” soils such as grease, oil, wax, and many plastics while moving through the fabric to loosen and carry away soil.

Solvent alone is not enough. A dry cleaning detergent is added by injection or charge to:

• Help the solvent penetrate the fabric

• Reduce redeposition so loosened soil does not settle back on garments

• Lubricate and begin loosening some “wetside” stains

• Control static and lint so particles are easier to remove

During this step, a pump continuously circulates solvent from the basket through the filter system. Pressurized filtration removes lint, soot, dyes, and insoluble soils such as fatty acids. Modern systems often use spin disc filters, cartridge filters, or a combination of both:

• Spin disc filters can be regenerated. Spinning the discs clears collected soil so the filter can be used many times before replacement.

• Cartridge filters must be replaced and disposed of when they become loaded with solids or when the activated carbon inside is depleted.

The type of solvent largely determines how long the wash cycle should run. For example, perchloroethylene usually requires a shorter wash cycle because of its high solvency power.

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2. The Extraction Cycle: Spinning Out The Solvent

When the wash is complete, garments are saturated with solvent. The extraction cycle removes most of it by spinning the load at high speed.

This centrifugal force pulls solvent out of the textiles and into the machine’s recovery system. In a properly timed extraction, roughly 80 percent of the solvent is removed from the load.

Correct extraction time is critical. If it is too short, excessive solvent carries into reclamation and slows the dry time. If it is too long, the extra spinning adds time and mechanical wear without meaningful benefit.

3. The Reclamation Cycle: Recovering Solvent For Reuse

The reclamation cycle, also known as solvent recovery, is where the machine heats the load and captures the remaining solvent so it can be reused.

Here is how it works:

1. A fan circulates air through the basket and recovery housing.

2. A steam heated coil warms that air and the garments.

3. The heat vaporizes solvent from the textiles into the moving airstream.

4. The solvent laden air passes over a refrigerated condensing coil.

5. The cold coil condenses the vapor back into liquid solvent.

6. The liquid flows into a water separator, which splits water away from solvent.

7. Clean solvent drains back into the storage tank, ready for reuse.

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The efficiency of this process depends on several factors:

• Airflow
  Lint bags, lint filters, and the button trap must be cleaned regularly, typically every third load. Restricted airflow leads to longer reclamation cycles and incomplete solvent removal.

• Steam pressure and temperature
  Steam entering the heating coil must be hot and strong enough to vaporize the solvent. Low pressure or lint-covered coils reduce heat transfer and weaken recovery.

• Refrigeration and condensing coils
  Condensing coils must be cold enough to bring the vapor back to liquid. A low refrigerant charge or lint buildup on the coil can significantly slow reclamation.

• Water separator maintenance
  The separator must be cleaned on a schedule to reliably separate solvent from water.

• Cycle control
  Many modern machines use a solvent sensor to close the steam valve when recovery is complete. Other machines rely on a fixed timer, which can over dry or under dry the load if not adjusted correctly.

4. The Cool Down Cycle: Protecting Fabric And Finish

The cool down cycle is usually programmed as part of reclamation, but it serves a different purpose.

Once most of the solvent has been recovered, the steam valve closes so no additional heat enters the system. The fan continues to circulate air over the refrigerated coil, gradually lowering the temperature of both air and garments to roughly 100°F.

This controlled cool down:

• Reduces the risk of severe wrinkling

• Helps prevent distortion or shrinkage of sensitive garments

• Makes pressing and finishing easier and more consistent

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Removing garments while they are still too hot increases the chance of creasing, distortion, or poor response to finishing equipment.

5. Why This Breakdown Matters For Your Plant

Understanding each stage of the dry cleaning process is more than theory. It gives you a roadmap for:

• Diagnosing problems such as redeposition, slow dry times, or lingering odors

• Setting realistic wash, extraction, and reclamation times for your solvent type

• Planning regular maintenance on filters, traps, coils, and the water separator

• Training staff to see how their checks and cleaning routines affect quality and cost

When wash, extraction, reclamation, and cool down are all tuned and maintained, your plant delivers cleaner garments, more predictable finishing, shorter cycle times, and better control over solvent and energy use.