Quality Coatings
Houston Powder Coaters follows dozens of standard operating procedures (SOPs) to ensure a quality product finishing.  From the time the pieces are received at the facility to the time it leaves our yard, each piece is handled with care and protected at every turn.  Each job is independently processed and inspected by hand to ensure piece counts and measurements.  Photographs are taken of any shipping damage, welding issues, or random anomalies.  Customers will be notified of any concerns before the blast process begins.
Masking / Plugging / Final Prep
To keep powder from reaching sensitive areas, Houston Powder Coaters will mask and plug all predetermined threaded holes and bolts, machined surfaces, and areas where overspray cannot be tolerated.  With over a dozen plug sizes and masking tapes available, HPC will work within conformance specifications to ensure accurate and precise coatings.  Finally, before the parts are maneuvered onto the railing system, all pieces will be hosed down with compressed air to ensure a clean and dust-free coating surface.

Surface Preparation
Surface preparation standards as defined by the Society of Protective Coatings (SSPC) and the National Association of Corrosion Engineers (NACE) can be achieved with prior notification and approval.  Houston Powder Coaters’ standard abrasive blast technique falls under the specification SSPC-SP7 / NACE4.

The resulting media-blasted surface shall be free of all visible oil, grease, dirt, dust, loose mill scale, loose rust, and loose coating when viewed without magnification.  However, by SP7 standards, tightly adhered mill scale, rust, and coating may remain on prior to coating if the adherent cannot be removed by lifting if off with a dull putty knife.  As galvanized and zinc-coated pieces may cause issues detrimental to the adhesion of powder coating, Brush-Off / Sweep Blasting is an acceptable surface preparation in the cleaning and anchor profiling of these substrates.

Houston Powder Coaters’ standard hand tool cleaning / hand etching falls under the specification SSPC-SP2.

Loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter are removed by “non-powered” hand tool methods, which include wire-brushing, scraping, chipping, and sanding.  Specifications for preparing galvanized steel for powder coating also include hand tool cleaning as an acceptable method to clean the substrate before surface profiling.

Note that these surface preparations also create anchor profiles from which the powder adheres to the metal.  The more aggressive surface preps will produce a deeper anchor pattern.  Typical steel grit blast media will produce anchor profiles between 2-4 mils.  Mild solvents and hand-etching will produce less.  The industry experts at Houston Powder Coaters will be glad to discuss these variables and the corresponding results to ensure proper coating adhesion.

Powder Coating

Houston Powder Coaters warrants that the process of pretreatment, powder application, and cure of all coated parts meet or exceed the industry standards set forth by the powder manufacturers.  Depending upon the criteria put forth by the individual powder coating supplier, HPC will preheat pieces which results in better powder adhesion and increased flow properties.  Certain aluminum pieces and galvanized parts will also receive preheating to reduce outgassing during the coating process.

Although the typical coverage of powder is 3-5 mils per coat (6-10 mils for a standard double coat), Houston Powder Coaters can apply thinner and thicker levels depending upon customer’s request.

Curing times vary due to the thickness of the metal, the type of metal, and the coating system that was applied.  In oven temperatures that exceed 425 degrees, the typical curing time ranges from 20 minutes to 2 hours.

Present day powder formulations allow for certain tolerances/graces above and below the ideal curing conditions.  This “bake window” allows Houston Powder Coaters to properly cure the spec’d powder within a broad temperature and bake time range.  In fact, these bake windows are the reasons why HPC can cure different size pieces with different colors in the same oven at the same time (at the same temperature).

Finally, when pieces exit the oven, final inspection tests are performed to ensure film thickness, proper curing, and even-flow.  These inspections are completed in one of two brightly-lit indoor quality-assurance areas.  HPC’s quality inspectors are trained to look for issues that will lead to coating failure.  If any problems are found, rejected pieces are sent to be reprocessed all over again.

Certificates of Compliance are available, but need to be discussed and agreed to at the onset of any job.