ASE B2 Painting & Refinishing cheat sheet

Substrate identification precedes any sanding: bare steel, galvanized, aluminum, plastic, and OEM e-coat each require different abrasives and primers.

Abrasive grit numbers are inverse to particle size: P80 is coarse, P400 is fine; each step should remove the scratch pattern of the previous grit.

Featheredge means tapering the old finish edge to zero thickness over a distance roughly 20 times the coating thickness so no ridge remains.

Galvanized steel must be abraded and treated with a zinc-compatible etch primer; direct topcoat over zinc causes poor adhesion.

Bare aluminum requires an etch or epoxy primer within the manufacturer's recoat window; aluminum oxide forms within hours of abrading.

Wax, silicone, and grease must be removed with a dedicated prep solvent before sanding, because sanding drives contamination into scratches.

Tack cloth removes loose dust but not oils; it is used after sanding and immediately before sealer or primer application.

Two-component epoxy primer is the standard for bare steel and aluminum because it provides corrosion protection and adhesion.

Fluid tip size controls flow: smaller tips (1.2-1.3 mm) suit basecoat and clearcoat, larger tips (1.6-2.0 mm) suit primers and high-build products.

Gun distance of 6-8 inches (15-20 cm) at 90 degrees to the surface produces an even coat; arcing or tilting causes mottling and dry spray.

Overlap each pass by 50 percent so film build is uniform; less overlap produces stripes and uneven metallic orientation.

Triggering technique: start the pass off the panel, release before leaving the panel, so no heavy deposit builds at the edges.

Air pressure is set with the trigger pulled (dynamic pressure); static readings overstate pressure and cause incorrect atomization settings.

Clean the fluid passage, air cap, and needle after every use; dried material in the air cap causes spitting and uneven spray patterns.

A spray pattern test on paper reveals defects: a crescent or split pattern indicates a clogged air cap hole or damaged fluid tip.

Never soak the entire gun in solvent; seals and packings degrade, causing leaks and inconsistent fluid delivery.

Mix ratio is expressed by volume or weight per the product data sheet; wrong ratio causes slow cure, soft film, or poor gloss.

Two-component products have a pot life measured from the moment of mixing; exceeding it causes gelling and loss of adhesion.

Induction time is the wait after mixing before spraying; some epoxies and primers require it for proper chemical reaction.

Metallic and pearl colors require the correct reducer and spray technique because flake orientation changes the perceived color.

Color matching uses a variant or formula lookup by vehicle code and a spray-out card compared under the same light source.

Tint colors are added in small increments; each addition shifts the formula, so record final weights for repeatability.

Viscosity is adjusted with the specified reducer, not thinner, unless the data sheet permits thinner for that product.

Filter strainers are used when pouring mixed paint into the gun cup to remove skins and undispersed pigment.

Downdraft booths move air vertically from ceiling filter to floor exhaust, carrying overspray away from the wet film.

Booth airflow must be balanced: excessive negative pressure pulls contaminants in, insufficient airflow leaves overspray in the work zone.

Intake and exhaust filters are replaced on a schedule or when pressure differential rises; loaded filters reduce airflow and cause defects.

Booth must be clean and free of dust before spraying; a contaminated booth deposits dirt nibs and trash in the finish.

Temperature and humidity affect flash time and dry time; most products specify an application range, commonly around 65-90 F.

Explosion-proof electrical equipment and grounding are required because solvent vapors are flammable; ungrounded parts cause static sparks.

Curing or baking accelerates crosslinking; follow the product's bake schedule to avoid solvent pop and loss of gloss.

Typical system: clean and prep, primer or sealer, basecoat, then clearcoat; each layer must be within its recoat window.

Flash time is the interval between coats to allow solvent release; spraying too soon causes runs, solvent pop, or trapped solvent.

Sealers are used to isolate substrates or unify color before basecoat; they also improve adhesion and prevent bleed-through.

Basecoat is applied to hiding or to the specified film build; metallic coats are often applied in lighter passes to control orientation.

Clearcoat is applied in two or more coats to reach the specified dry film thickness, usually around 2 mils per coat.

Wet-on-wet application means applying the next coat before the previous is fully cured, within the manufacturer's stated window.

Dry film thickness is measured with a gauge; mils are thousandths of an inch, and 1 mil equals 25.4 micrometers.

Masking tape and paper protect adjacent panels; edges must be sealed to prevent overspray and hard tape lines.

Runs and sags occur from too much material, too slow a reducer, or too close a gun distance; correction is sanding and polishing or repaint.

Solvent pop appears as small craters from trapped solvent escaping during baking; caused by too-short flash time or excessive film build.

Orange peel is a textured surface from poor atomization, wrong reducer, or too-fast dry; correction is wet sanding and polishing.

Fish eyes are circular craters caused by silicone or oil contamination on the surface or in the air line; requires cleaning and repaint.

Dry spray is a rough, sandy texture from too much distance, too much air pressure, or too fast a solvent; correction is sanding.

Blistering is solvent or moisture trapped under the film, often from inadequate flash time or a contaminated substrate.

Bleed-through is discoloration from a soluble underlying layer; a sealer or isolating primer prevents it.

Mottling or striping in metallics is caused by uneven overlap, gun distance, or air pressure that disturbs flake orientation.