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Kirk Johnstone Puts Cork Plaster to the Test "On The Trowel" at TIWI Training Academy


At the TIWI Training Academy, We had the pleasure of having On The Trowel’s very own Kirk Johnstone put TIWI Thermal Cork Plaster through its paces: the UK’s original trowel-on cork insulation. This thin, breathable, carbon‑negative finish is designed for solid walls, helping tackle condensation and black spot mould, for good proving why Thin Internal Wall Insulation (TIWI) is becoming the go to upgrade for solid wall homes.

Kirk Johnstone One the Trowel Cork Plaster

Kirk is exactly as genuine, knowledgeable, and passionate in person as he is on his channel, a true asset to the plastering industry and a champion for sharing skills and supporting others.

If you follow Kirk, you already know he keeps it real, always aiming to help others raise their game. It was brilliant to see that same energy and honesty behind the scenes with us.


Who is Kirk Johnstone? The Man Behind “On The Trowel”


Kirk Johnstone known to thousands on YouTube as “On The Trowel” is exactly the same off‑camera as on: skilled, straight‑talking, and an absolute diamond. His practical tutorials, experience days and no‑nonsense approach have made him one of the UK’s most trusted plastering voices online. Bringing him into the TIWI Academy meant one thing: a real test, with real feedback.


Internal Applications: Thin, Breathable, Thermal Comfort Our Thermal Cork Plaster is a trowel-on, 3-4mm breathable layer designed for solid walls. Inside, it delivers:


  • Thermal comfort uplift without stealing room space (no radiator moves)

  • Natural breathability to help combat condensation and black spot mould

  • Acoustic comfort for quieter rooms

  • A smooth, modern finish (pairs beautifully with lime plaster for a natural, eco‑friendly aesthetic) Available in 32 colours with custom RAL on request, it’s a premium, carbon‑negative finish homeowners can feel—and plasterers can confidently offer.


External Applications: Base Coat and Crack Filling

External Use: Base Layer and Crack‑Bridging Partner Externally, Cork Plaster works as a flexible base coat to even minor imperfections and bridge hairline cracks before a Cork Spray finish. This combo delivers a durable, weather‑resistant system with the warmth, breathability, and flexibility cork is known for.


Getting to Know the Real Kirk Johnstone

Between passes, tea, and plenty of trade chat, we got to know the real Kirk, exactly the guy you see on YouTube: humble, curious, and committed to helping plasterers level up. He asked the right questions, pushed the material, and shared practical insights every applicator cares about from open time to feathering and finish quality. Thanks for everything you do for the trade, Kirk. Here’s to more collaboration and raising standards together!


TIWI Academy On the Trowel Cork Plaster

Why Thermal Cork Plaster Belongs in Your Toolkit For plasterers and contractors:

  • High‑margin, problem‑solving finish clients value

  • Short learning curve with premium results

  • Upsell potential: colours, feature walls, interior/exterior systems



For homeowners and property managers:

  • Warmer rooms with minimal disruption

  • Helps tackle condensation and black spot mould

  • Breathable, natural finish that looks and feels premium


Why Choose TIWI CorkSpray

We specialise in thin, breathable cork systems for internal and external surfaces—engineered for solid wall comfort, moisture control, and long‑term durability. With our exclusive material partnership and UK‑wide installer support, TIWI CorkSpray is setting the standard for trowel‑on cork insulation.



Ready to Learn More?


Contact TIWI CorkSpray

Sole Distributors, VIPEQ UK (TIWI CorkSpray) is proud to be the sole distributor of the leading cork coating brand VIPEQ Globall, To learn more about The UK’s first and original trowel‑on cork insulation material and to gain exclusive access, leads, support and training, become a Certified Installer today: www.tiwicorkspray.co.uk/certified-application


 
 
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