Why specifications matter
A floor sanding contractor will default to whatever system they're comfortable with unless told otherwise. If you don't specify the product, the primer, the number of coats, and the sheen level, you'll get whatever they usually do -- which may or may not match what you had in mind.
A clear spec protects the what you actually wanted and gives both parties something to hold the outcome against.
What to include in a timber floor finish specification
Which primer and why. Bona Prime Intense (grain pop, warmer tone), Prime Classic UX (standard seal), Prime White (lighten the timber), or no primer for oil systems.
Specific product name. "Water-based polyurethane" is too vague. "Bona Traffic HD" is a spec. "Bona Craft Oil 2K in Neutral" is a spec.
Extra Matt, Matt, or Satin. Be specific -- the difference between 10% and 20% gloss is visible in natural light and will change the feel of the space.
Standard Bona system: 1 seal coat + 2 topcoats. Some projects warrant 3 topcoats for added protection. State it explicitly.
Stain product, colour code, application method. Request a sample panel on the actual timber before full application.
Final grit level (typically 100-120 grit for poly, 80-100 for oil). Dust extraction required. Edge detailing standard -- this is where most quality issues originate.
"No solvent-based products to be used." Or: "Solvent-based sealer not permitted under any Bona topcoat." This prevents contractors substituting cheaper primers.
Common spec mistakes
Too vague: "Apply water-based polyurethane in satin." This leaves the product choice, primer choice, and coat count entirely to the contractor.
No primer specified: The primer changes the colour and grain appearance of the final result. Skipping the primer spec is like specifying a paint colour but not the undercoat.
Specifying oil without maintenance plan: Oil finishes need periodic maintenance. If the client doesn't know this, they'll blame the contractor when the floor dulls in year two.
Not requesting a sample: Always request a coated sample on the actual timber species being used. Stains and finishes react differently to different woods.
Bona specifier paragraphs
Bona publishes ready-to-use specification paragraphs for each product system. These can be dropped directly into architectural specifications.