Many people contributed to this module.  The technical team members include:
National Shipbuilding Research Program SP-3 Panel, Todd Pacific Shipyard, Detyens Shipyard, Atlantic Marine Florida LLC, Carolina Equipment and Supply Co. (CESCO), UHP Projects, and NLB Corporation. My apologies if I missed someone.

There are many other factors of inspection of the substrate when wet abrasive or waterjet methods are used.  For workshops or further details or training, contact Dr. Lydia Frenzel.

The material presented in this training module is intended to be non-commercial and, as indicated by the diverse source of photographs and list of contributors, is derived from a cross-section of equipment and materials suppliers to the pressurized water cleaning industry manufacturers, experienced contractors, as well as NSRP volunteers and staff.
The use of a specific photo or video does not constitute endorsement or preference for a particular supplier.  They are intended as illustrative examples and to acknowledge the companies with individuals who contributed to this program and the advancement of the industry.

Companies who contributed to the review and discussion include:

National Shipbuilding Research Program SP-3 Panel

Todd Pacific Shipyard
Detyens Shipyard
Atlantic Marine Florida LLC
Carolina Equipment and Supply Co. (CESCO)
NLB Corporation
UHP Projects
Flow International
KMT Aqua-Dyne
Hammelmann Corp.
Surface Technologies Corp.
Elzly Corp.
Applied Research Lab- Penn State
Hydrochem Industrial Services
Parker Polyflex
International Paint
Hempel
Jotun
PPG Protective & Marine Coatings
General Shipyards
NASSCO
Chlor*Rid
Holdtight Solutions
Chariot Robotics LLC
Journal of Protective Coatings and Linings (JPCL)
CleanerTimes
Sarafina
Alcoa
Stolt Nielson Tanker
National Surface Treatment Center
Society of Protective Coatings (SSPC)
National Association of Corrosion Engineers (NACE)
Navy Sea Systems Command (NAVSEA)

Bibliography
These papers are included for further reading with permission from JPCL, CleanerTimes, and Marine Log. All rights are retained by the publishers.

Gilbert, Doug, New Hydroblasting and Slurryblasting Standards Issued, JPCL, Jan., 1995, p. 64-69
Kelly, John, There’s More than One Kind Of Rust, Marine Log, May, 1996, p. 18
Swearingen, Mark, UHP Water Jetting Offers Advantages, Marine Log, May, 1996, p. 20
Tanner, John, Flash Rust, A Primer, CleanerTimes, April, 2001, p. 20
Frenzel, Lydia, The ABC’s of Surface Preparation, CleanerTimes, April, 2001, p. 42-44
Frenzel, Lydia, Flash Rust: Color, CleanerTimes, May 2001, p. 26 & 27
Frenzel, Lydia, Flash Rust: Amount, CleanerTimes, June 2001, p.32 & 33
Frenzel, Lydia, Remote Waterjetting Offers Inconspicuous Coatings removal on LNG tank, JPCL, Dec., 2002, p. 57-65
Frenzel, Lydia M, Flash Rust, CleanerTimes, Sept, 2004 p 24-27

The Pressure Sensitive Tape Test described by Hempel is a modification of ISO 8502-3 (Pressure Sensitive Tape test for dust) and is not mentioned in VIS-4.  The tape test can be used as a permanent record.  If lint deposition is a concern, the project specification may require use of a different technique to determine the level of flash rust, such as the pressure-sensitive tape test. Those responsible for establishing the requirements and those responsible for performing the work can agree to the use of a different technique to determine the level of flash rust

Place a piece of tape (as specified in ASTM D 3359) in a length of at least 5 cm (2 in) on the surface and rub thoroughly with a fingertip–not a nail–to make the tape adhere firmly.  Peel off the tape and place it on a piece of white paper for reference. Repeat this process 9 additional times (for a total of 10 tests) using a fresh piece of tape each time and apply the tape to the same spot.  Assess the appearance of the tape and the surface.

The results from the pressure sensitive tape test lead to the same conclusions as the tape tests.  For further details or training on this item, contact Dr. Frenzel.

Tape Test from a Moderate Flash Rust (MFR) Surface (Below).

 4. Based on the subjective methods, Flash Rust is classified as
           • None
           • Light
           • Moderate
           • Heavy

The following metric table was developed by Pete Ault, Elzly Technology Corporation. Click Table to enlarge.

Table of Metrics used in Flash Rust

ALL of the VISUAL GUIDES are used in the SAME WAY!
 Look at the flash rust
• straight on,
• within arm’s length,
• in good lighting,
• prior to painting.
 Allow time to remove, if necessary, excess loose flash rust prior to painting

Look at the surface and decide if you can see through the rust or if it obscures the surface.  Make sure that the rust is not splotchy black.

Look at the color.   Color can vary depending on the type of steel. The color is affected by the age and type of steel and, in the field, certainly might appear differently than the descriptive terms. Current language being adopted by NACE and SSPC will remove the COLOR language. 

Determine Quantity of loose rust dust. Lightly wipe the surface with a cloth.

The methods to evaluate Flash Rust are Subjective.
• Visual Appearance and
• Assessment of amount of Loose Dust
 Cloth Wipe in hand
 Cloth Swatch in hand
 Cloth around a Brush
 Tape

Below: the substrate is dry- but it is  darker (overall) than the original substrate.
This surface is dry within 5 minutes. The standard pictures in VIS-4 do not provide these types of illustrations of pressure-washed surfaces. The upper half is not washed; the lower half has been pressure washed.

Brush test on the Pressure Washed Surface.

Brush Test before Pressure Wash.

After Pressure Wash- there is very little faint color on cloth
After pressure washing the substrate, there is a faint marking at the upper edge of the cloth where the brush bristles contacted the surface.
The area has been mitigated from moderate to light flash rust.

 Prior to the application of paint, the substrate must meet the procurement specifications.
 Typical field remediation includes:
 Pressure washing
 Broom brushing
 Blowing off with pressurized air
 Solvent cloth or dry cloth wiping
 Vacuum

Upon polling contractors, it appears that pressure washing is the preferred practice. The appearance after pressure washing when the surface dries will be DIFFERENT; rust dust is washed away.  Typically the surface has a darker appearance.  The metallic sheen might disappear.  The standard pictures in VIS-4 do not provide illustrations of pressure-washed surfaces.
In the first two pictures, the substrate was pressure washed (ca 1000 psi) to remove the loose dust so that the substrate would meet a “light” flash rust requirement..
The substrate dried in a few minutes.  Flat surface can take longer to dry.

INSPECT the AREA AFTER PRESSURE WASHING.
Note that the loose dust is removed.
However, the stains on the right have remained.
The inspector, contractor, paint manufacturers, and owners (all the responsible parties in a coatings project) should note streaked areas and obvious runs. 

In this example, the source of the water that created the original flash rust came from a hole in the ship that most likely had salts or oil and greases.  Special attention should be given to those areas. Look to the project specifications as to what other inspections might be required.

At the right, notice that some areas are not washed, some have dried, and some are still drying.

Here are more pictures showing the same type of situation, where some areas are not yet washed, some are dry, and some are still drying.

Close up of area on right in picture above.

To Repeat: the inspector, contractor, paint manufacturers, and owners (all the responsible parties in a coatings project) should note streaked areas and obvious runs. 

In this example, the source of the water that created the original flash rust came from a hole in the ship that most likely had salts or oil and greases.  Special attention should be given to those areas. Look to the project specifications as to what other inspections might be required.
All the defects can be seen.  There are stains, but NO loose rust dust.

All the defects can be seen.  There are stains, but NO loose rust dust.

This is the result of the Brush Wipe Test on Heavily Stained & Heavy Flash Rust Area

Before Pressure Washing

Before Pressure Washing.

After Pressure Washing. Hand wiping test.

After Pressure washing. Brust test.

A direct comparison between hand wipe and brush test on pressure washed moderate flash rust indicates no differences.

 None
 Light
 Moderate
 Heavy
Adopt the method with which you feel most comfortable and that is portable to different projects and sites.

Examples of LFR on Swatch, wipe, and Brush

Example of MFR on swatch and brush wipe.

HFR on Swatch

HFR on Brush Wipe

HFR with Swatch, Brush, and Wipe

 Brushing flash rust is quick, simple, and very reproducible.
 Adopt a standard brush and standard cloth.
 Be consistent with one swipe and in the same direction and duration.
 Practice brush strokes with even pressure
 Keep the contact area consistent.
 Cloth can be cut at the area of color transfer and placed in permanent file or scanned for color.

Heavy Flash Rust formed from water coming from holes.
Different section where Light, moderate, and heavy flash rust had formed in close proximity.

Left to right, Light, Moderate, Heavy. Brush tests taken at the same time from three different areas.

Some color is transferred from light flash rust.

This view has the sun Illuminating the surface.  Substrate appears darker as it is in shadow. Inspection is biased by lighting angle.