ACTFLEX 727 SEP Epoxy sealing primer
Two-component, low-volatile epoxy sealing primer for damp substrates
Damp-tolerant epoxy primer that seals concrete and bonds polyurea and epoxy coatings to it.
ACTFLEX 727 SEP coverage, coats and cure times
Two-component, low-volatile epoxy sealing primer for concrete, render and masonry. It goes under FORSPEC polyurea coatings, including ACTFLEX 737 PU, and under ACTFLEX 747 TC, and can go on damp surfaces with no standing water.
- Consumption
- 0.3–0.35 kg/m²one coat, sound concrete of normal porosity · TDS p3
- Coverage
- 11.6–13.5 m²per 4.5 kg set, practical, 10% wastage allowed · TDS p4
- Mix ratio
- 3.5 : 1Part A to Part B by weight, never by volume · TDS p2
- Pack
- 4.5 kg setPart A 3.5 kg + Part B 1 kg · TDS p3
- Pot life
- 30 mintypicalfrom mixing; 15 minutes in high ambient temperature · TDS p3
- Full dry
- 24 h or lesstypicalwalkable and ready to overcoat · TDS p3
- Overcoat within
- 24 hof full dry; beyond that, abrade and re-prime · TDS p3
- Coats
- 1one coat as a sealing primer · TDS p4
- Apply at
- 10–30°Cair and surface, 85% RH maximum, 3°C above dew point · TDS p3
From the FORSPEC data sheet, TDS-727SEP · Revision 1 · 12 November 2026. Times are at 25°C and 50% relative humidity unless the data sheet says otherwise. Typical = FORSPEC’s own typical value, not a laboratory-certified one.
Where ACTFLEX 727 SEP is used
Use it for
- Primer on concrete, render and masonry under FORSPEC polyurea coatings
- Under ACTFLEX 737 PU and under ACTFLEX 747 TC
- Damp substrates where the programme has no time to dry out
- Abraded metal and dense concrete where high adhesion is needed
- Sealing porous, dusty surfaces that would outgas through the coating
- Basements, lift pits, tank and bund interiors
Know before you start
- Not for standing water: damp is fine, but remove all free and ponded water first
- Not a moisture barrier: above 4.5% moisture, use two coats of ACTFLEX EP250
- Not UV stable and not a finished surface: it must be overcoated
- Not over silicone, bitumen, particleboard or coatings that are not sound and bonded
How to apply ACTFLEX 727 SEP
- 01
Prepare
Concrete cured 28 days, ground, scarified or captive-blasted to CSP 3–5, then vacuumed. Render and screed cured 7 days. Steel blasted to Sa 2½. Damp is fine, standing water is not.
- 02
Check moisture
Remove free and ponded water and measure moisture. Above 80% RH, 15 g/m²/24 h or 4.5% on a non-destructive meter, apply at least two coats of ACTFLEX EP250 to its TDS.
- 03
Mix
Weigh Part A and Part B at 3.5 : 1 by weight. Mix by machine at low speed until uniform, scraping the sides and base. In hot weather mix for no more than 2 to 3 minutes. Use within 30 minutes.
- 04
Apply
One coat by roller, brush or trowel at 0.3 to 0.35 kg/m², worked firmly into the surface. No misses, and no ponding in low points or blowholes.
- 05
Blind
On open, porous or profiled surfaces, blind the wet primer with clean, oven-dried quartz sand to full refusal. Remove all loose sand once it has cured.
- 06
Overcoat
Allow 24 hours for full dry, then apply the coating within 24 hours of that point. If the window is missed, or the primer is contaminated or rained on, abrade and re-prime.
A short guide from the data sheet. Read the full ACTFLEX 727 SEP TDS before you start.
ACTFLEX 727 SEP test reports and compliance
- Adhesion
- 1.5 MPa or greaterManufacturer test data, typical (FORSPEC R&D to GB/T 16777)
- Alkali resistance
- No change after 360 hours in saturated calcium hydroxide solutionManufacturer test data, typical (FORSPEC R&D to GB/T 9265)
- Water resistance
- No change after 360 hours water immersionManufacturer test data, typical (FORSPEC R&D to GB/T 1733)
- Volatile content
- 5% or lessManufacturer test data, typical (FORSPEC R&D to GB/T 16777)
Results as stated in the data sheet, TDS-727SEP · Revision 1 · 12 November 2026. Warranty up to 25 years, depending on the system: ask FORSPEC which term applies to your system.
ACTFLEX 727 SEP questions
How much ACTFLEX 727 SEP do I need?
Allow 0.3 to 0.35 kg per square metre in one coat. A 4.5 kg set covers 11.6 to 13.5 m² in practice, with 10% allowed for wastage. Rough, porous and profiled surfaces use more, so set the rate on a trial area.
Can it go on damp concrete?
Yes. It cures in damp conditions and goes straight onto a damp surface. It will not displace water, so remove all free and ponded water first.
How long before I can coat over it?
Allow 24 hours for full dry at 25°C and 50% RH, then overcoat within 24 hours of full dry. Past that window, or if the primer is contaminated or rained on, abrade and re-prime.
How do I mix it?
Weigh both parts: 3.5 parts Part A to 1 part Part B by weight, not by volume. Mix by machine at low speed until uniform. Pot life is 30 minutes, or 15 minutes in high ambient temperature, so mix only what you can lay.
What goes over ACTFLEX 727 SEP?
FORSPEC polyurea and epoxy coatings, including ACTFLEX 737 PU spray-applied polyurea and ACTFLEX 747 TC. It is not UV stable, so it must be overcoated and never left exposed.
Is it a moisture barrier?
No. Where moisture is above 80% RH, 15 g/m²/24 h or 4.5% on a non-destructive moisture meter, apply a minimum of two coats of ACTFLEX EP250 to its TDS.
Used with ACTFLEX 727 SEP
ACTFLEX 727 SEP data sheet
Always work from the current data sheet. Every FORSPEC TDS and SDS →
Specify it. Or buy it.
Send the drawings or photos and FORSPEC comes back with the system, the details and the quantities. Or find a FORSPEC stockist for ACTFLEX 727 SEP.