Scanning Spray Best Practices for Accurate Digital Impressions

Scanning spray is one of those consumables that seems simple until something goes wrong. Applied correctly, it's invisible in its effect — restorations fit, models scan cleanly, workflows run. Applied incorrectly, it introduces dimensional error that shows up as fit problems you can't otherwise explain. Here's what matters.

What Scanning Spray Does

Most dental lab scanners and intraoral scanners operate on structured light or laser triangulation principles. These systems struggle to capture highly reflective surfaces (polished metal, shiny ceramics) and sometimes highly translucent or dark surfaces. Scanning spray deposits a thin, uniform titanium dioxide or chalk-based coating that creates a matte, scannable surface with consistent light reflection properties.

The coating must be:

• Thin enough not to add measurable material thickness (which would produce undersized restorations)
• Uniform enough to scan without gaps (which produce scan artifacts)
• Stable enough not to shift or flake during the scan

Application Technique: What Actually Matters

Distance

Hold the spray can 20–30cm from the surface. Too close: heavy, uneven coat; potential dimensional buildup. Too far: sparse, non-uniform coverage with gaps.

Duration Per Pass

Short bursts. A single light pass is typically sufficient. You should barely be able to see the coating on the surface — if it looks white and thick, you've applied too much. Multiple light coats are better than one heavy coat if the surface is complex.

Coverage of Margins

Pay particular attention to margin areas. The scanner needs to capture the margin clearly for the CAD software to accurately locate it. Heavy spray buildup on a margin adds dimensional thickness at exactly the point where dimensional accuracy matters most. Light, even coverage at margins is essential.

Allow to Dry

Scan immediately after applying — don't wait for the spray to dry completely, but do give it 2–3 seconds for the propellant to evaporate. Scanning into wet spray can scatter light and produce artifacts. Scanning into a fully hardened coat that has started to crack also produces artifacts.

When Scanning Spray Is Required

• Scanning shiny metal surfaces (cast frameworks, Ti bases, abutments)
• Scanning highly polished ceramics or lithium disilicate before crystallization
• Scanning model materials that are highly reflective (certain die stone formulations)
• When scanner error messages indicate poor surface data quality

When Scanning Spray Is Not Required

• Most intraoral scans (modern IOS systems handle oral surfaces without spray; using intraoral spray is uncommon)
• Scanning matte model surfaces (most stone and plaster models scan well without spray)
• PMMA and most CAD/CAM materials post-milling (matte surface scans cleanly)

Common Problems and Causes

• Crown too tight: Spray applied too heavily, especially on prep die. The extra material thickness translates to a reduced internal space in the CAD design.
• Scan gaps / missing data: Spray coverage not reaching the entire surface; particularly in undercut areas. Inspect coverage from multiple angles before scanning.
• Spray buildup in corners: Corners trap spray. Multiple light passes from different angles, rather than one direct pass, minimizes this.
• Residue affecting bonding: If scanning a piece that will be bonded (ceramic to Ti base, etc.), remove the spray coating before bonding. Titanium dioxide coating prevents resin adhesion.

Spray Removal

After scanning, remove spray with a gentle air blast or a water rinse. On models that will be used for physical try-in, remove spray residue before the clinician uses the model. Most commercial scanning sprays are water-soluble and clean off easily.