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SKU: STOPGAP12105

Stopgap P121 Primer - 5L

£37.53
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Free next-working-day delivery Eligible mainland UK postcodes FREE
Free next-working-day delivery on this item The only exceptions are the postcode areas listed below.
Order by 3pm Monday–Friday For same-working-day dispatch
Delivery aim Next working day For eligible in-stock orders
Small parcels Royal Mail Tracked 24 Tracking sent after dispatch
Larger orders FedEx tracked delivery Including suitable oversized items
Orders placed Monday–Thursday before 3pm will be delivered the next working day.
Orders placed before 3pm Friday will be delivered Monday. Orders placed after 3pm Friday or over the weekend will be delivered Tuesday.
Working days are Monday–Friday, excluding UK bank holidays and announced closure periods.
Courier delays are rare, but can occasionally occur due to circumstances outside our control. Tracking details will be provided so you can follow your delivery.
Excluded postcode areas Online delivery orders cannot currently be accepted for the areas below.
Area Excluded postcodes
North-east Scotland AB31–AB45, AB51–AB56
Central & northern Highlands FK19–FK21; all IV
Outer Hebrides All HS
Arran & Cumbrae KA27–KA28
Caithness, east Sutherland & Orkney All KW
Argyll & Inner Hebrides PA21–PA38, PA41–PA49, PA60–PA78
Perthshire & western Highlands PH1 1, PH1 3, PH1 4, PH5–PH10, PH15–PH26, PH30–PH44, PH49–PH50
Shetland All ZE
Northern Ireland All BT
Channel Islands & Isle of Man All GY, JE & IM
Isles of Scilly TR21–TR25

Need delivery outside our standard area? Please contact us before ordering and we’ll check whether a separate service can be arranged.

Postcodes, timings & full delivery terms
Click & Collect Salisbury Trade Counter FREE
Select Click & Collect at checkout.
Monday–Friday, 7:30am–4pm.
We’ll email you as soon as your order is ready to collect.
Unit 1 Penton Business Park, Stephenson Road, Salisbury, SP2 7NP.

F. Ball Stopgap P121 is a high-performance acrylic primer developed to prepare calcium sulphate (anhydrite) screeds before the application of Stopgap smoothing compounds and compatible flooring adhesives. It improves adhesion, controls substrate absorbency and helps prevent unacceptably rapid drying of smoothing compounds and adhesives.

Its distinctive blue colour provides excellent visual coverage during application, helping to ensure the entire floor has been primed evenly. Stopgap P121 is non-flammable, easy to apply and suitable for use over normal underfloor heating systems.

Why Choose F. Ball Stopgap P121?

  • Specifically developed for calcium sulphate and anhydrite screeds.
  • Promotes excellent adhesion of smoothing compounds and adhesives.
  • Controls substrate absorbency.
  • Helps prevent rapid drying of adhesives and smoothing compounds.
  • Blue colour provides visual control during application.
  • Easy to apply by roller or brush.
  • Non-flammable formulation.
  • Suitable over normal underfloor heating installations.

Ideal For

  • Calcium sulphate screeds.
  • Anhydrite screeds.
  • Preparing subfloors before Stopgap smoothing compounds.
  • Reducing substrate absorbency.
  • Domestic flooring projects.
  • Commercial flooring installations.
  • Underfloor heating systems.

Professional Advice

Calcium sulphate screeds require the correct preparation before levelling compounds or adhesives are applied. Stopgap P121 is specifically formulated for these substrates and helps provide a consistent, well-bonded surface for the next stage of your flooring installation.

Once primed, choose the appropriate Stopgap levelling compound depending on your project requirements, substrate type and installation times.

Technical Specifications

Product Type Acrylic Primer
Pack Size 5 Litres
Colour Blue
Application Method Brush or roller
Coverage Approximately 40m²–60m² per 5L depending on substrate porosity*
Drying Time Approximately 1 hour under normal conditions*
Suitable Subfloors Calcium sulphate (anhydrite) screeds.
Underfloor Heating Suitable for normal underfloor heating installations.
Flammability Non-flammable.

Prepare Your Subfloor Like a Professional

Correct preparation is essential for a smooth, durable and long-lasting flooring installation.

1. Check for Moisture

Ensure the screed has reached the manufacturer's recommended moisture content before priming or installing floor coverings.

2. Prime the Surface

Apply Stopgap P121 evenly across the prepared calcium sulphate screed. The blue colour helps ensure complete and consistent coverage.

3. Repair Any Imperfections

Use Stopgap Micro Rapid for minor repairs and feather edging, or Stopgap 400 Repair for larger repairs before levelling.

4. Choose the Right Levelling Compound

Stopgap Fast-Track 30 – Ideal when speed is the priority.

Stopgap 700 Superflex – Flexible formulation for timber and plywood.

Stopgap 1200 Pro – Excellent for refurbishment projects over suitable adhesive residues.

Stopgap 300 HD – Heavy-duty smoothing compound for demanding environments.

Need Help Choosing?

Not sure which primer your subfloor requires? Contact our flooring specialists with details of your substrate and we'll help you choose the correct preparation system.

Important Information

  • For internal use only.
  • Apply only to clean, sound and correctly prepared subfloors.
  • Allow the primer to dry before applying smoothing compounds or adhesives.
  • Always follow the latest F. Ball Technical Data Sheet.
  • Coverage varies depending on substrate porosity.

*Coverage and drying times are based on normal site conditions. Highly porous substrates, lower temperatures or increased humidity may affect performance.

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