When stock goes off-condition

Stock that looks the same as the day it was filled is not necessarily the same product.

A cleaner ages

Fragrance degrades, particularly at high or low pH.

Color fades in light.

pH drifts.

Viscosity moves.

The preservative depletes, so a product two years old has less protection than one at six months.

And the container is slowly being acted on the whole time.

What to check

Retained samples from each batch, looked at on a schedule: appearance, odor, pH, viscosity.

Bottle condition: any paneling, swelling, weeping at the neck, or weight loss.

The closures, particularly any metal parts, for corrosion.

And a real bottle from the oldest stock rather than only the retained sample, because stock in a warehouse has had a different history from a sample on a shelf.

How long it keeps

Most water-based cleaners are good for a year or two, and the limit is usually fragrance and preservative rather than cleaning performance.

Establish it rather than asserting it, from the retained samples, and put a date code on the bottle so you can tell how old a returned unit is.

A product with a longer stated life needs a longer stability program behind it.

Rotation

Sell oldest first, which needs a date code rather than a memory.

Store out of direct sun and away from heat, which is where most warehouse degradation happens.

And do not ship declining stock to a wholesale account, where it becomes their opinion of the range. Discount it directly or dispose of it.

References