Does Developer Dry Time Impact Indication Strength?

Learn about the available properties of developers and the relationship between dwell time and inspection quality

Basic Chemical Composition of Non-Aqueous Developer

The developer consists of two types of components; the solids that are responsible for developing indications and the solvent with which the solids are suspended in. The solvent the manufacture chooses determines the rate at which the developer dries. Developer manufacturers have many solvents to choose from. Each solvent has its own unique properties including flash point, odor, viscosity, vapor pressure, and evaporation rate all of which are carefully considered when deciding on the final formulation.  

Impact on Indications

In theory, a developer that dries rapidly would allow for increased throughput of test pieces, something that is desirable to all companies performing NDT. Knowing this, why doesn’t Magnaflux simply formulate their developers with the fastest evaporating solvent available? The answer is that we do not want to sacrifice inspection quality for speed.

Magnaflux developers have been formulated with a specific ratio of solvents that optimize the developer dry rate. The dry rate of the Magnaflux developer is optimized for both ease of application as well as maximizing the inspection quality. This ratio of solvents and their corresponding dry rate have a proven record of easy application and high inspection quality.

Developers which dry more rapidly than Magnaflux developers are typically more difficult to apply. The developer dries immediately on contact with the part, often leading to excessive developer unintentionally being applied. This excessive application of developer can lead to the obstruction of flaws on a part. The Magnaflux developer has been carefully formulated so that the dry rate allows for an even, consistent coat of developer to be applied, increasing the quality of the inspection. Typically, the amount of penetrant wicked from a flaw actually increases with dry time. With difficult to detect flaws, the slower drying solvent portion of the Magnaflux developer can aid the solids in bringing the penetrant to the surface of the part, increasing the quality of the inspection.

The solvent ratios of Magnaflux developers have been carefully formulated and tested by Magnaflux chemists to achieve the most advantageous developer dry time for the customer, prioritizing ease of application and high inspection quality over speed of development.