If your coating doesn’t stick, nothing else matters. Durability, gloss, chemical resistance—all of it falls apart if the bond between your coating and the substrate fails. That’s why adhesion testing is one of the most important steps in quality control for refinishers. Whether you're coating bathtubs, tile, or countertops, checking adhesion helps you catch surface prep issues before they become expensive callbacks.

Here’s how to do it right.

Why Adhesion Fails

Before we get into testing, let’s talk about why coatings fail to bond:

• Poor surface prep – Dirt, grease, soap film, or even invisible residues can kill adhesion.
• Wrong primer or no primer – Not all substrates bond well with topcoats alone.
• Too slick a surface – High-gloss or non-porous surfaces (like porcelain) need etching or adhesion promoter like Crosslink III.
• Improper curing conditions – Cold temps, moisture, or recoating too soon can all sabotage adhesion.

  Knowing how to test adhesion helps you troubleshoot and verify that your process is dialed in.

  Easy Adhesion Tests You Can Do On-Site

  Crosshatch Tape Test (ASTM D3359 Method)

  This is the go-to test for smooth, hard surfaces.. Here’s how:

  You’ll need:

  • A utility knife
  • Metal ruler or straight edge
  • Adhesive tape (like 3M #600 or ASTM-approved tape)
  • Good lighting

  Steps:

  • Make 6–10 parallel cuts through the coating to the substrate, about 2mm apart.
  • Make another set of cuts perpendicular to the first to form a small grid or "hatch."
  • Press a piece of adhesive tape firmly over the cuts.
  • Smooth it down and rub it a few times to ensure full contact.
  • Pull the tape off quickly at a 180° angle (straight back).
  • Examine the area.

  Grading:

  • 5B (best) – No coating removed.
  • 4B–3B – Minor flaking along edges
  • 2B–0B (fail) – Large chunks or complete squares come off.

  If you're getting anything less than 4B, you have a problem. Stop and investigate.

  Pro Tips to Improve Adhesion

  • Always make sure the substrate is clean & dry.
  • Use an adhesion promoter like Crosslink III  or etch for glossy or non-porous surfaces.
  • Test every new coating system you use, don’t trust what everyone tells you. Test for yourself.

  Bottom Line

  Adhesion testing doesn’t take long, but it can save you hours of rework and headaches down the line. Add it to your routine because the best way to impress a customer is with a coating that stays put.

  Watch our video on How To Check Coating Adhesion in 3 Simple Steps

  For more articles like this visit our Blog. If you want to join other like-minded professional refinishers to discuss process, visit the Facebook group Resurfacing Contractors Network.

  Learn More About Professional Bathtub Refinishing

  TopKote has everything you need for your refinishing project including materials and training. If you are looking for a professional, contact us and we will direct you to a Topkote Pro nearest you.

  Shop Tub Refinishing Products Become A Topkote Pro Find A Topkote Pro