1
Q
Sources of Contamination
A
Pre-Clean
- poor pre-cleaning
- pre cleaning water or chemicals
Wash & Rinse
- splashing and drag out
- emulsifier (lipophilic) & developer
Penetrant
- contaminates the developer and depletes the emulsifier
2
Q
Water contaminates water wash penetrant:
A
emulsifier contained in this penetrant makes it hydroscopic
- reduces penetrating ability
- reduces washability
- cloudy and more viscous
- viscosity decrease with more contamination
- seperates
- corrosive
3
Q
Water contaminates post emulsified penetrant:
A
- not as serious, water and oil don’t mix
- parts at bottom of tank not dwelling
- tank itself could corrode
4
Q
other contaminates and penetrant
A
- loss of wetting ability
- increased viscosity
- dilution of tracer dye
- loss of brilliance
- affects washability
5
Q
Problems with the use of tanks:
A
contamination is easier than aerosols
- reusing product (drag out, overspray)
- environment (dust, dirt, humidity, condensate)
- leaky roofs, pipes
- evaporation
- change in viscosity
- change in water tolerance
- affects washability
- higher concentrations (emulsifier and developer)
6
Q
What is storage deterioration?
A
can keep product for long periods in kept sealed.
- water in barrel tops if outside
- evaporation
- propellant loss in aerosol
- cold temps = separation &/or freezing
- hot temps = loss of brilliance, chemical reaction, burst container
7
Q
Common storage practices:
A
- warm storage desired (65°C)
- sealed containers
- stored on side (especially developers)
- stock rotation
- attention to shelf life (especially in aerosols)
8
Q
Evaluation of test materials
A
- test specimens
- TAM (test and monitor) & PSM (penetrant system monitor) panels
- comparison blocks
- cracked panels
- hydrometers (aqueous developers)
- refractometers (hydrophilic emulsifiers)
- visual appearance
- comparing to unused samples
