60–80% of a quality paint job is prep you never see — washing, sanding, filling, masking, priming. It’s the difference between a finish that lasts ten years and one that lifts in two. Here’s what good prep actually involves, step by step.
Any painter can put colour on a wall. The trade is in everything that happens before the brush — the wash, the sanding, the filling, the sealing, the priming, the masking. That work doesn’t show in the finish. It only shows when the finish stays clean three years later. On a quality job, 60–80% of the effort is prep you never see.
Which is exactly why it’s the first thing a cheap quote cuts. It’s the invisible line — the one the homeowner can’t check on handover day.
Wash
Sugar-soap removes oils, kitchen residue and grime. Paint won’t bond to a dirty wall — it lifts.
Sand + fill
Nail holes, cracks and surface roughness filled and sanded flat. The quality of the finish is decided here.
Mask + drop sheets
Floors, fixtures and edges protected. Skipped by cowboys; you pay for it in cleanup and overspray.
Prime
A primer matched to the surface and topcoat. New plaster, old enamel and bare steel each need a different one. Skip it and the topcoat doesn’t bond.
On older homes the list grows: lead-safe handling on pre-1970 surfaces, rust treatment and etch primer on steel, anti-microbial primer on mould-prone bathrooms and inland walls. None of it is visible in the photos. All of it decides the lifespan.
The paint is the easy part. The prep is the whole job.
Ask this, exactly
“Walk me through the prep on my surfaces — the wash, what you’ll fill and sand, and which primer goes where, and why.”
A working painter talks about prep before colour — it’s where their margin and their reputation live. A cowboy steers straight to “what colour were you thinking?”
Brushline puts prep on its own lines in every quote — wash, sand and fill, masking, primer — with a dollar figure beside each. Not because it’s glamorous, but because it’s the part most likely to be quietly missing from the cheaper quote next to ours. Once it’s on the page, you can see what you’re actually comparing.