Equipment Performance Flashcards

What is the primary purpose of a densitometer in a pressroom environment?

Answer: To measure ink film thickness on printed substrates

A densitometer measures the optical density of ink on a substrate, providing data on ink film thickness and consistency.

When a printing press shows inconsistent ink laydown across the sheet width, the most likely cause is:

Answer: Uneven roller pressure or worn rollers

Uneven or worn ink rollers fail to distribute ink uniformly across the form, causing variation in density across the sheet width.

In offset lithography, the term 'dot gain' refers to:

Answer: An increase in halftone dot size from film to final print

Dot gain is the phenomenon where halftone dots print larger than their intended size, caused by ink spread and optical effects.

Which measurement tool is used to verify the squareness and dimensional accuracy of a printed sheet?

Answer: Diagonal gauge or T-square

A diagonal gauge or T-square is used to verify that sheets are cut square and that dimensions are within specification.

A spectrophotometer differs from a densitometer primarily because it:

Answer: Measures full spectral reflectance to calculate CIE Lab values

A spectrophotometer measures reflectance across the visible spectrum and calculates colorimetric values such as CIE Lab, enabling precise color matching.

The recommended procedure when a printing plate shows signs of blinding (loss of image) during a press run is to:

Answer: Check and correct the fountain solution chemistry

Plate blinding is typically caused by acidic or chemically imbalanced fountain solution that desensitizes the image area, so correcting the solution chemistry resolves the issue.

In gravure printing, the quality of ink transfer is most directly influenced by:

Answer: The viscosity of the ink relative to the cell depth and speed

In gravure, ink viscosity must be matched to cell depth and press speed to ensure complete cell emptying and consistent transfer to the substrate.