Red Seal Auto Refinishing flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Isocyanate sensitization

Repeated or single high exposure to isocyanate hardeners can sensitize a worker; afterwards even tiny exposures may trigger asthma attacks. Supplied-air respiratory protection and skin coverage are required when spraying 2K isocyanate products.

VOC content regulation

Volatile organic compound limits are set per litre of coating minus water and exempt solvents. Compliant systems usually pair waterborne basecoat with high-solids clearcoat; mixing compliant and non-compliant products does not exempt the resulting mixture.

Spontaneous combustion of rags

Solvent-soaked rags and filter media self-heat as solvent oxidizes. Store them in a self-closing metal container with water or lay them flat outdoors; a piled rag bin can ignite without any external ignition source.

Desiccant vs refrigerated dryer

A refrigerated dryer produces a pressure dew point near 3 °C, adequate for general air. A desiccant dryer reaches about -40 °C and is used where moisture-sensitive clearcoat demands very dry air.

HVLP transfer efficiency

HVLP guns are limited to about 10 psi at the air cap and transfer 65 percent or more of the material to the surface. Conventional high-pressure guns atomize finer but transfer only 25 to 40 percent.

Zahn cup viscosity

A Zahn cup measures the seconds for a fixed volume of material to drain through a calibrated orifice. Compare the drain time to the product data sheet at the specified temperature before adjusting with thinner.

Plastic identification codes

ISO codes moulded on the back of plastic parts identify the polymer, such as PP, PE, ABS, PC, PA, or PUR. The code determines whether an adhesion promoter, flexible additive, or special primer is needed.

Galvanized steel preparation

Do not sand through the zinc coating. Clean, apply a wash primer or epoxy primer rated for zinc, and avoid products that react with zinc and cause blistering or poor adhesion.

Water-break test

Water sprayed on a prepared surface should sheet evenly. Beading or breaks in the water film indicate oil, wax, or silicone contamination that must be removed before priming or topcoating.

Delta E colour difference

Delta E quantifies the measured difference between a sample and a formula in L*a*b* space. Values below about 1.0 are generally invisible; values above about 2.0 are noticeable to most observers.

Metamerism in colour matching

A metameric match looks correct under one light source but wrong under another because the pigment composition differs from the original. Matching pigment type, not only measured colour, reduces metamerism.

Three-angle metallic matching

Metallic and pearl colours are compared at face, 45 degrees, and flop angles. Face is the direct view, flop is the side view; the flop index describes how lightness changes with angle.

Epoxy primer recoat window

Epoxy primer provides corrosion protection and adhesion on bare metal. Its recoat window is typically about 7 days at 20 °C; after that the surface must be sanded before the next coat for adhesion.

Etch primer limitations

Acid etch primer promotes adhesion to bare steel and aluminium in a thin film. Do not apply it over body filler, galvanized steel, or cured paint, and do not topcoat it with polyester products.

Sealer function

A sealer is a thin coat over primer or old finish that blocks solvent penetration and colour bleed and improves topcoat adhesion. Tinting it toward the topcoat colour improves hiding.

Guide coat use

A contrasting mist coat over primer surfacer reveals low spots and sanding scratches during blocking. All guide coat must be sanded away before topcoat, or dark speckles show through the finish.

Clearcoat dry film thickness

Typical clearcoat dry film is 40 to 60 microns. Too thin reduces UV protection and gloss; too thick raises the risk of solvent pop, cracking, and runs. Verify with a film thickness gauge after cure.

Basecoat hiding and flop

Basecoat coverage is judged by opacity, not coat count. Metallic basecoats are applied to hiding plus one orientation coat; over-application causes mottling and reduces the metallic flop.

Flash-off before baking

Flash-off lets solvent evaporate before the bake. Baking too early traps solvent, causing pop and blisters. Flash-off time depends on temperature and airflow and is specified on the product data sheet.

Candy colour reproduction

Candy finishes use a transparent tinted mid-coat over a metallic base. Final colour depends on base shade and candy coat count, so both must be recorded to reproduce the finish later.

Matte clear limitations

Matte and satin clears contain flattening agents and cannot be sanded and polished to restore gloss, because polishing changes the gloss level. Film thickness variation also shows as gloss variation.

Special-effect pigment base coat

Chameleon and interference pigments require a specific ground coat, often black or a matched shade, and a clearcoat. They cannot be tinted into a standard mixing bank formula.

Fisheye cause and repair

Fisheyes are circular craters caused by silicone, oil, or wax contamination. Sand back to the substrate, clean thoroughly, and use fisheye eliminator only as a last resort because it can harm adhesion.

Solvent pop diagnosis

Solvent pop appears as small blisters or pinholes when trapped solvent escapes during bake. Prevent with longer flash-off, thinner coats, slower solvent, and lower bake temperature; repair by sanding and recoating.

Sandscratch swelling

Sanding scratches reappear after topcoat because solvent swells the primer and the scratches rise. Prevent by sanding finer and applying sealer; repair by sanding back and re-priming.

Adhesion failure testing

Cross-hatch (ISO 2409) or pull-off (ASTM D4541) testing locates the failure plane. Failure at the substrate interface indicates poor preparation; failure within the primer indicates incomplete cure or low film build.

Spray pattern test

Spray a test pattern on cardboard at working distance. A uniform pattern with soft edges is correct; a split or heavy-centre pattern indicates a clogged or damaged air cap or a misaligned fluid tip.

Gun spitting diagnosis

Spitting from the nozzle usually means a loose or dirty fluid tip or worn needle packing. A pulsating pattern points to air supply fluctuation or a partly clogged fluid passage.

Gun inlet pressure setting

Set pressure with a gauge at the gun inlet, not at the compressor, because hose and filter losses reduce pressure. HVLP requires about 10 psi or less at the air cap.

Estimate versus supplement

An estimate covers visible damage; a supplement documents hidden damage found after disassembly. Additional work requires customer or insurer authorization before it proceeds.

Work order traceability

Record the VIN, colour code and variant, panel list, and product batches used on every job. This supports warranty claims, future colour matching, and material safety traceability.

Blend versus full panel

A blend refinishes part of an adjacent panel to hide a colour transition; a full panel refinish covers the whole panel. Explain cost and colour-match risk and obtain written approval before blending.