Waterborne or solvent basecoat?
Both give a great finish. The right choice depends on your booth and the way you work.
| Waterborne basecoat | Solvent basecoat |
| Drying | Needs good air movement in the booth. | Dries fast, little affected by humidity. |
| VOCs and booth | Less solvent in the booth; the 420 g/L limit is easier to meet. | Must also meet 420 g/L, ready to spray. |
| For whom | Shops set up for waterborne drying (blowers, venturis). | Shops without waterborne drying equipment, touch-ups. |
Either way, the clear on top is usually a 2K clear.
Primer surfacer or sealer?
Two primers, two jobs. Mixing them up costs sanding time or hiding.
| Primer surfacer | Primer sealer |
| Job | Fills sanding scratches and small imperfections. | Seals and evens out the base right before colour. |
| Sanding | Sanded before colour, dry or wet. | Wet-on-wet: no sanding before basecoat. |
| When | After filler, or on a surface that needs levelling. | Factory-primed new part, base to even out. |
VOC limits: 250 g/L for primer surfacer, 340 g/L for primer sealer (SOR/2009-197).
Wet-on-wet, explained
One less sanding step on new parts.
- How it works
- Basecoat goes over the primer sealer after a short flash, with no sanding.
- Where
- Mostly on new parts already primed at the factory (e-coat).
- What you save
- A sanding step and booth time.
- Tinted undercoat
- Light, medium or dark grey to suit the colour: the basecoat hides in fewer coats.
Follow the flash time on the technical data sheet.
Fast or standard clear?
The clear often sets the length of the booth cycle.
| Standard clear | Fast clear |
| Cycle | Usual flash and bake. | Less waiting: the booth frees up sooner. |
| Typical use | Large areas, overall paint jobs. | Spot repairs, high-volume shops. |
| Watch for | Booth time. | A shorter application window. |
Clear coating VOC limit: 250 g/L ready to spray. Some clears are designed for a shorter or lower-temperature cure.
The paint code is not enough
The paint code is a starting point, not a guaranteed match.
- Factory variants
- One code often has several variants: lighter, darker or yellower.
- Ageing
- Sun and time change the original paint.
- The tools
- Formulas and variants, sprayed colour chips, a spectrophotometer reading.
- The spray-out
- Spray a test card and compare under a colour-match lamp before the part.
Give us the vehicle’s colour code or VIN.
Blending into the next panel
Even a well-matched colour can look different from one panel to the next.
- How it works
- The colour is faded into the adjacent panel so the eye does not see the transition.
- Plan it
- Repairs go better when the blend is planned from the start.
- The clear
- Clear then covers the whole panel, or is blended per the planned method.
Plan it at the estimate: blending is often billable.
Painting a plastic bumper
Without the right prep, paint peels or cracks.
- Clean
- A cleaner designed for plastics, before and after sanding.
- Bond
- Adhesion promoter or a primer with plastic additive on thermoplastics (PP, TPO).
- Stay flexible
- A flex additive prevents cracks on parts that bend.
Adhesion promoter VOC limit: 840 g/L.
Bare metal: epoxy or etch?
On bare steel, galvanized or aluminum, the primer provides adhesion and protection.
| Epoxy primer | Etch primer |
| Job | A strongly adhering anti-corrosion barrier. | Bites into the metal for adhesion. |
| Typical use | Large bare areas, long-lasting repairs. | Small spots sanded through to metal. |
| Next | Surfacer or colour, per the data sheet. | Covered with a primer surfacer or sealer. |
Some primers combine epoxy protection and surfacer in one product. Wash primer VOC limit: 660 g/L.
Choosing a body filler
The right filler sands easily and does not show through the paint.
- Universal
- For most dents on steel.
- Finishing
- In a thin coat, for pinholes and fine scratches.
- Fibreglass
- To reinforce and fill holed or repaired areas.
- Aluminum, flexible
- For aluminum panels and parts that flex.
Measure the hardener per the data sheet: too much or too little hurts sanding and durability.
Abrasives: which grit, when?
Each step has its grit. Skipping one leaves scratches under the colour.
- Coarse
- Stripping, taking to bare metal and shaping filler.
- Medium
- Finishing filler and sanding primer surfacer.
- Fine
- Prep before basecoat and blend areas.
- Very fine
- Fixing clearcoat defects, before polishing.
Discs, sheets, sponges, non-wovens and blocks: tell us your sander and your step.
Masking it right
Sloppy masking means a hard edge or a bleed to fix.
- Automotive tape
- Holds through the bake and comes off without residue.
- Fine line
- For clean edges on stripes, mouldings and blends.
- Foam tape
- In openings and jambs: no visible paint line.
- Paper and film
- To cover the rest of the vehicle fast and clean.
Liquid masking and booth coatings help keep the booth clean.
Orange peel, runs, craters
Three common defects, three families of causes.
- Orange peel
- Film too thin, wrong viscosity or reduction, gun too far, booth too hot.
- Runs
- Too much product or coats too close together. Fine-sand, then polish or recoat.
- Craters
- Contamination: silicone, oil, dirty compressed air. Dedicated degreaser and filtered air.
A photo of the defect helps us find the cause with you.
VOCs: what the law says
In Canada, SOR/2009-197 limits VOCs in automotive refinishing products.
- Who it covers
- Anyone who makes, imports or sells these products, distributors included.
- How
- The limit applies to the ready-to-spray product, hardener and reducer included.
- Examples
- Colour 420 g/L, clear 250, primer surfacer 250, primer sealer 340.
- Exemptions
- Non-refillable aerosols and very small touch-up containers.
Follow the mixing ratios on the data sheet: they are set to stay under the limit.
Breathing safely with 2K
2K hardeners contain isocyanates, a cause of occupational asthma.
- Spraying
- Quebec’s CNESST points to supplied-air respirators: no cartridge is approved for isocyanates.
- Sanding
- A particulate respirator may be enough, depending on the dust.
- Where
- In a ventilated booth, with exposure kept as low as possible.
Ask us for the safety data sheets of your products.
Conventional or HVLP gun?
Part of the sprayed product never reaches the part.
| Conventional | High efficiency (HVLP) |
| On the part | Often 20 to 40% of the product (EPA). | About 50 to 65% of the product. |
| Overspray | Lots of overspray in the booth. | Less overspray, cleaner booth. |
| Setup | Higher air pressure. | Stick to the specified inlet pressure. |
A clean gun with the right tip, properly set, matters as much as its type.