Blinding and Pegging
September 1, 2026
Why Is My Screen Plugging Up?
If your screen isn't letting material through like it used to, take a look at the openings.
Photo: Screen with pegging problem
Blinding and pegging are two of the most common screening challenges for Unified’s customers – all across the country.
Some people use the terms interchangeably to describe material covering the screen surface. Both problems reduce available open screening area and limit the screen's ability to separate material, but they are different problems.
Blinding happens when damp, sticky or clay-rich material coats the screening surface and covers the openings.
Pegging is when individual particles become wedged in the openings and stay there.
Why is Blinding and Pegging So Bad for the Rock Plant?
BLINDING: Covers the surface with a film or layer of dirt or fines.
PEGGING: Jams individual screen openings with stuck particles.
Some of the warning signs are pretty easy to recognize:
Spot the Symptoms
A screen that normally performs well may suddenly struggle after heavy rain, a change in the material coming out of the pit, or a significant change in feed.
You’re Not Screening
A clogged cloth means you’re simply carrying material over the screen – fines stay in your product, forcing re-screening.
Screen Damage
A pegged rock grinds on the wire all day, causing holes in the cloth - and then you’re running out-of-spec material.
Crusher Wear
Fines running through the crusher a second time create extra wear on manganese.
Your Screen Media Matters
The right screen media can also help when blinding or pegging is an ongoing challenge.
Different wire configurations and screen-media options offer different combinations of open area, flexibility, wear life and resistance to plugging. The best choice depends on what you're screening—including gradation, moisture, abrasiveness and the product you're trying to make.
No two pits are alike. If changing material conditions are making screening more difficult, it may be time to reevaluate what's on your deck.