Best Rust/Painting Strategy

Its been a while but your absolutely correct, fresh water wash down after ospho allot of bosns dont know this or ignore it. Regardless its written in the application instructions.

Companies spend a lot of money on paint and coating systems unfortunately much of that money is wasted during application by ship’s crew. I have found very few Chief Mates and fewer bosuns knew the application specs of the paint they had or followed them if the specs were in hand.
When I was on the Far East run the window of opportunity was from Hawaii to Guam and from there perhaps as far as Kaohsiung. The weather was generally good to do the work and surfaces could be reasonably prepped. On the way back to the States where it was cold, wet and the weather crappy it was a total waste of time and money. I once told the Mate he would be ahead of the game if he just mixed the paint, let it set up and throw the bucket over the side for all the good he was doing (with spray coming over the deck). Trying to make the ship “look good” for the office coming back across the north Pacific just made the situation worse.
When power tooling, wire wheels should NOT be used, grinding and sanding wheels should. Grinding/sanding wheels or discs give a good surface profile for the paint to adhere. Wire wheels polish the steel resulting in an extremely poor surface profile. The result is akin to painting glass. Oil, grease, salt and other contaminates must be removed. The surface must be dry.

See section 4.


Has anyone seen the ad’s for Dustless Blasting machines on the Motor Trend Channel? I always thought that would be a slick system for fabric maintenance.

Has anyone had a difference with anti corrosive pigments in the paint? For example Interprime 198 vs 234.

I believe (but not sure) Interprime 234 uses a zinc compound as the “anti corrosive” pigment. This helps create a metallic film that acts as a physical barrier, as well as providing cathodic protection for the underlying steel. Note that it is not sold as a “Zinc Rich” primer. The type of primer that should be used is dependent on the top coat going over it.

Paint should be viewed as a system and not individual components. The recommended top coats are not the same for Interprime 198 and 234.

There was an ad in the local Virginian Pilot over 30 years ago for painters. Caught my eye “Sailors need not apply”. There were also signs downtown Norfolk well prior to that “Sailors and dogs keep off the grass”. Agreed somewhat on the painter thing, but not so much on the other. They liked our money, but didn’t like us. I don’t spend much money in that town.

My father told me about seeing that sign during WW2… then “someone” would kick it over…

Went through the NAVSEA manuals and came up with a shortened list. Let me know what your feedback is:

Painting Guidelines

631-7.2.4 SURFACE PREPARATION. The single factor most affecting the performance of….coatings is the preparation of the surface to be coated, both as to method and to degree of care. Surfaces to be coated shall be completely free from rust, loose paint, dirt, scale, oil, grease, salt deposits, moisture, and other contaminants. Surface preparation procedures detailed in Chapter 5 apply and are supplemented by requirements given in this section. (Refer to Chapter 2.)

  1. Fresh Water Wash
  2. Chipping and Removing rust and old paint.
  3. Feathering
  4. Rust Treatments
  5. Fresh water wash
  6. Primer application.
  7. Top Coat Application.
  1. Fresh Water Wash

3.10.2-Accomplish degreasing/cleaning prior to surface preparation to ensure that the surface is free of contaminants in accordance with SSPC-SP 1 of 2.5. (NAVSEA Item No 009-32, Cleaning and Painting Requirements, page 19)

631- Freshwater Washing. For all types of substrate materials, before surface preparation to the specified cleanliness level using any method other than waterjetting or wet abrasive blasting, the area to be cleaned shall be washed with low pressure freshwater to remove any residual soluble salts. The freshwater washing pressure shall be maintained between 2,000 and 3,000 PSI and shall not contain corrosion inhibitors. Freshwater washdown shall be followed by an adequate period of time to allow the surface to dry prior to blasting. For best efficiency in removing surface salts, the freshwater used for washing should have a maximum conductivity of 200 micro siemens/cm.

631- Removing Surface Contaminants. Surface contaminants shall be removed to ensure coating adhesion and minimize the possibility of defects such as blistering, peeling, flaking, and under-film rusting. Surfaces to be painted for preservation shall be completely free of mill scale, corrosion, loose paint, dirt, oil, grease, salt deposits, and moisture. To prevent embedding contaminants during surface preparation, oil or grease shall be removed before using hand tool, power tool, or abrasive blasting surface preparation using solvent cleaning as described in SSPC-SP 1. Rusted surfaces shall be freshwater rinsed, where practicable, to remove water soluble contaminants before abrasive blasting or additional surface preparation by other means. For non-critical coated surfaces, weld spatter and flux compounds should be removed by grinding or chipping in order to prevent premature paint failure on the welds.

  1. Chipping and Removing rust and old paint.
    631-5.3.3 POWER TOOL CLEANING TO BARE METAL. When power tool cleaning to bare metal is specified herein, the surface cleanliness shall meet the requirements of SSPC-SP 11, Power Tool Cleaning to Bare Metal. Metallic surfaces that are prepared according to SSPC-SP 11, when viewed without magnification, shall be free of all visible oil, grease, dirt, dust, mill scale, rust, paint, oxide, corrosion products, and other foreign matter. Slight residues of rust and paint may be left in the lower portion of pits if the original surface is pitted. Although the SSPC-SP 11 standard requires a minimum of a one (1) mil profile, unless otherwise specified herein, the minimum required profile when SSPC-SP 11 is specified for critical coated areas defined in paragraph 631-11.2 is 2 mils. (See paragraph 631-5.14.)

  2. Feathering

a) Use a grinding or sanding wheel only to feather paint. Do not use a wirewheel Avoid buffing the rust, as this spreads dust and contaminants into the corroded metal. Buffing corrosion creates a smooth surface that prevents good adhesion of paint.
b) Edge Preparation- Edge Preparation After application as the coating is still liquid, there is a tendency for liquid coatings to pull back from sharp edges leaving a very thin layer of paint which can quickly break down in service. Grinding the edges of cut outs, drainage holes, etc., as shown in Section 4, Figure 5, greatly helps liquid coatings stay with increased dry film thickness. Roughness from grinding to the edges can also improve the adhesion and coverage of the coating around the edge. IMO PSPC for both ballast tanks and crude oil tanks require at least three passes of the grinding disc or equivalent over the cut edges for giving at least 2 mm (0.08 in.) radius of round edges. Even one pass of grinding as required from IMO PSPC for void spaces, could give a better surface for painting than no preparation.
In addition, during coating applications, stripe coating to the edges is also beneficial in providing long-term protection. IMO PSPC for both ballast tanks and crude oil tanks require a minimum of two stripe coating to edges and welds unless for weld seams only, the second stripe coating can be skipped for avoiding over thickness of dry film. (ABS THE APPLICATION AND INSPECTION OF MARINE COATING SYSTEMS p41)
c) 3.6.4-Accomplish feathering of adherent paint remaining after the required surface preparation by creating a smooth, 1 to 2 inch wide transition area between the prepared surface and the adherent paint using hand or power tool sanding or grinding. (NAVSEA Item No 009-32, Cleaning and Painting Requirements, page 14)

  1. Rust Treatments
    3.10.4 Limit the square footage of surfaces being prepared for preservation to an area that can be coated prior to the occurrence of flash rusting and/or oxidation. Remove any flash rust prior to coating. (NAVSEA Item No 009-32, Cleaning and Painting Requirements, page 19)

a) Phosphoric Acid- (Ospho, Rustreat, Alumabrite etc) After drying, wipe white residue off with thinner or mineral spirits. Alternatively, fresh water wash ospho.
631-5.8.2 ACID CLEANING USES. Acid cleaning removes surface contaminants by treating the surfaces with a phosphoric acid solution containing small amounts of solvent, detergent, and a wetting agent. Unlike alkaline cleaners, acid removes light rust and slightly etches the surface to ensure better coating adhesion. Many types of phosphoric acid metal cleaners and rust removers are available and each is formulated to perform a specific cleaning job.

631- Wash-Off Method. The wash-off method involves the application of the acid cleaner, a time allowance for the cleaner to act, a thorough rinsing, and a drying period before painting.

b) Tannic Acid- (Enrust, Corroseal, Corotech, Rust Converter, etc) Apply one coat in one direction. After 30 minutes, apply another coat in a perpendicular direction to the first coat.

631- LIMITATIONS. The use of rust converters shall be limited to preventive measures taken by a ship’s crew while a ship or submarine is underway and no other corrosion control procedure is available. The use of rust converter products shall not be substituted for standard NAVSEA-approved corrosion control practices for ship’s Hull, Mechanical, and Electrical (HM&E) preservation, but shall serve as a temporary measure only until proper corrosion control procedures can be employed. Rust converters are not authorized as a pretreatment for any coating system and shall be removed prior to the use of a NAVSEA-standard corrosion control system. Rust converters shall never be over-coated with any coating system. Rust converters are water based products and should not be used on wetted surfaces or on surfaces subject to continuous immersion. Immersion service represents a severe environment for which these products were not designed.

a. Loose rust, scale, and other contaminants are to be removed using hand tool (SSPC-SP and power tool (SSPC-SP 3) cleaning methods.
b. Solvents or detergents must be used to remove as much oil and grease as possible followed by a freshwater wash/rinse to remove any residual detergent and soluble salts. (Solvents shall not be used for submarine applications.)
c. Allow surface to dry prior to applying rust converter.
d. Water-based rust converters shall be applied on a dry surface by brush only. Spraying shall not be used, in order to prevent accidental contact with metals or other materials that may be damaged by the chemical rust converters.
e. Rust converters should be applied in one or more treatments, according to the manufacturer’s directions.

  1. Fresh water wash to remove all dust trapped contamination from the corroded, uneven steel and metal and paint dust from the area.

  2. Primer application.

a. Check dew point and substrate temperature.
b. First coat-Brush the first coat of primer into corroded steel, pits, welds, doubler joints, and edges before applying the main coat of primer.
c. Second coat-covers all surfaces equally.
d. Cover primer within the specified window of painting. The time to overcoat with one part primer is much smaller for 1 part primer. Avoid leaving primer uncoated for more than 7 days. For example, the recommended overcoat time for Interprime 198 by Intertac 665 is 1-3 days.
3.1.16- When applying paint, multiple coats must be of contrasting colors, unless specifically stated otherwise in Tables One through 8. (NAVSEA Item No 009-32, Cleaning and Painting Requirements, page 7)

631-7.1.3 APPLICATION OF STRIPE COATS. For all areas where stripe coating is required herein, the stripe coat shall be applied to edges, weld seams, welds of attachments and appendages, cutouts, corners, butts, foot/ handholds, and other mounting hardware (non-flat surfaces). The stripe coating requirement also applies to difficult-to-access areas such as the back side of piping and the underside of Tee and I-beam stiffeners. Unless otherwise specified herein, stripe coats shall be applied in accordance with the NAVSEA-approved ASTM F718 coating data sheets, except that the stripe coat DFT requirements shall be as specified herein. The paint used to perform stripe coating shall be not be thinned. Stripe coating shall be applied after the primer coat has dried. Stripe coats shall be neat in appearance, and shall have minimal runs, drips, or sags. Stripe coats may be brushed, rolled, or sprayed. The stripe coat shall encompass all edges and welds, as well as at least a one inch border on each side of the edge or weld. Each stripe coat shall be of the specified paint system and shall be a different color from both the paint over which it is being applied and the next coat in the system. If a product only comes in two colors, the stripe coat shall contrast with the color of the previous coat. Inspections of the primer coat shall be conducted prior to stripe coat application. When measuring intermediate or total system DFT to determine compliance with the specified thickness, DFT readings shall not be taken in areas where stripe coatings have been applied. Stripe coat DFT requirements specified herein shall be checked by the painter in-process, using WFT measurements. Stripe coat DFT requirements are provided for each coating system table in Section 8, and are summarized in Table 631-1-4.

  1. Top Coat Application.

a. Coat the primer within the specified window.
b. When coating with non skid, roll parallel to the ship’s main axis.

Paint Products and Desired Thickness
• 14 mil DFT
• Intergard 264/269 then Interthane 990
Bulkheads and Overheads
• 8 mil DFT
• Interprime 198/234 then Interlac 665

Paint Coverage
Product Coverage (square feet/gallon) Dry Film Thickness (mils)
Interlac 665 (Alkyd) 481 1.6-2
Interprime 234 (Alkyd) 465 2
Interthane 990 (Polyurethane) 457 2
Intergard 264 (Epoxy) 257 5
Intergard 269 (Epoxy) 471 1.6
Interprime 198 (Alkyd) 219 3

• Cutting metal on top of paint will destroy the top layer of paint. A fine metal dust will coat all metal unless it is removed quickly.
• Chase cable stud welds as they happen. Do not allow them to rust.

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Just put down a coat of International 264. What a difference! It is much thicker than 198/269, way more abrasion resistant. Really excited to see how it stands up to the test of time.