|
Water Blasting NACE Standard RP-01-72: Removal of oil grease dirt, loose rust, loose mill scale, and loose paint by water
<br />at pressures of 2,000 to 2,500 psi at a flow of 4 to 14 gallons per minute.
<br />Stucco S-W 22 :Must be clean and free of any loose stucco. If recommended procedures for applying stucco are followed, and
<br />normal drying conditions prevail, the surface may be painted in 30 days. The pH of the surface should be between 6 and 9.
<br />Wood—Exterior— S-W 23: Must be clean and dry. Prime and paint as soon as possible. Knots and pitch streaks must be
<br />scraped, sanded, and spot primed before a full priming coat is applied. Patch all nail holes and imperfections with a wood filler
<br />or putty and sand smooth. Caulk should be applied after priming.
<br />Wood—Interior — S-W 24: All finishing lumber and flooring must be stored in dry, warm rooms to prevent absorption of
<br />moisture, shrinkage, and roughening of the wood. All surfaces must be sanded smooth, with the grain, never across it. Surface
<br />blemishes must be corrected and the area cleaned of dust before coating.
<br />Vinyl Siding, Architectural Plastics, PVC & Fiberglass: — S-W 24: Clean the surface thoroughly by scrubbing with warm,
<br />soapy water. Rinse thoroughly, prime with appropriate white primer. Do not paint vinyl with any color darker than the original
<br />color. Do not paint vinyl with a color having a Light Reflective Value (LRV) of less than 56 unless VinylSafe l Colors are used.
<br />If VinylSafe® Colors are not used and darker colors lower than an LRV of 56 are, the vinyl may warp. Follow all painting
<br />guidelines of the vinyl manufacturer when painting. Only paint properly installed vinyl siding. Deviating from the
<br />manufacturer's painting guidelines may cause the warranty to be voided.
<br />Previously Coated Surfaces — S-W 12: Maintenance painting will frequently not permit or require complete removal of all old
<br />coatings prior to repainting. However, all surface contamination such as oil, grease, loose paint, mill scale dirt, foreign matter,
<br />rust, mold, mildew, mortar, efflorescence, and sealers must be removed to assure sound bonding to the tightly adhering old
<br />paint. Glossy surfaces of old paint films must be clean and dull before repainting. Thorough washing with an abrasive cleanser
<br />will clean and dull in one operation, or, wash thoroughly and dull by sanding. Spot prime any bare areas with an appropriate
<br />primer. Recognize that any surface preparation short of total removal of the old coating may compromise the service length of
<br />the system. Check for compatibility by applying a test patch of the recommended coating system, covering at least 2 to 3 square
<br />feet. Allow to dry one week before testing adhesion per ASTM D3359. If the coating system is incompatible, complete removal
<br />is required per ASTM D4259.
<br />Touch-Up, Maintenance and Repair
<br />For a protective coating system to provide maximum long-term protection, regularly scheduled maintenance is required.
<br />Maintenance includes inspection of painted areas, cleaning of surfaces to remove oils, chemicals, and other contaminants, and
<br />touch-up of areas where the coatings have been damaged. Highly corrosive areas, such as those subjected to frequent chemical
<br />spillage, corrosive fumes, and/or high abrasion or temperature areas should be inspected frequently — every six months, for
<br />example. Areas exposed to less severe conditions, such as interiors and exteriors of potable water tanks, may be inspected
<br />annually to assess the condition of the coating system.
<br />The SSPC-VIS 2, Standard Method for Evaluating Degree of Rusting on Painted Steel Surfaces, can be used as a guide to
<br />determine appropriate touch-up and repairs maintenance schedules. Touch-up would be suggested when the surface resembles
<br />Rust Grade 5-S (Spot Rusting), 6-G (General Rusting), or 6-P (Pinpoint Rusting). Surface preparation would generally consist
<br />of SSPC-SP2, SP3, SP 11, or SP12. Overcoating a well protected, but aged steel surface showing no evidence of rusting, may be
<br />achieved by Low Pressure Water Cleaning per SSPC-SP12/WJ4, and applying an appropriate coating system.
<br />Full removal of the existing coating system by abrasive blasting would be recommended when the surface resembles Rust
<br />Grade 3-S (Spot Rusting), 4-G (General Rusting), or 4-P (Pinpoint Rusting). When the coating system has deteriorated to
<br />encompass approximately 33% of the surface area, it is always more economical to consider full removal and reapplication of
<br />the appropriate protective coating system.
<br />Mildew —Prior to attempting to remove mildew, it is always recommended to test any cleaner on a small, inconspicuous area
<br />prior to use. Bleach and bleaching type cleaners may damage or discolor existing paint films. Bleach alternative cleaning
<br />solutions may be advised.
<br />Mildew may be removed before painting by washing with a solution of I part liquid bleach and 3 parts water. Apply the
<br />solution and scrub the mildewed area. Allow the solution to remain on the surface for 10 minutes. Rinse thoroughly with water
<br />and allow the surface to dry before painting. Wear protective eyewear, waterproof gloves, and protective clothing. Quickly
<br />wash off any of the mixture that comes in contact with your skin. Do not add detergents or ammonia to the bleach/water
<br />solution.
|