Repair Systems — 03 — Facade & External Envelope
Primer systems — per substrate type
Technical product reference for sealant adhesion primer systems used in facade joint remediation on Australian Class 2 strata buildings. Covers universal and substrate-specific primers for concrete, masonry, render, aluminium and glass — correct primer selection is critical for sealant adhesion and long-term joint performance. Always confirm primer requirement and substrate compatibility with the sealant manufacturer before application.
What are sealant primer systems and when are they required?
Sealant adhesion primers are thin chemical coatings applied to joint faces before sealant application to improve bond strength between the sealant and the substrate. Whether a primer is required depends on the specific combination of sealant product and substrate type — this information is always found in the sealant manufacturer's Technical Data Sheet (TDS). Never assume a primer is or is not required without checking the TDS for the specific sealant-substrate combination.
Product Reference
3 products — sealant primer systems by substrate type — scroll to view all
Sika Primer-3N
Universal sealant primer — porous substrates — PU and silicone compatible
System Description
Sika Primer-3N is a one-part, solvent-based universal primer for porous substrates used prior to application of Sikaflex sealant systems. It is suitable for priming concrete, masonry, render, mortar, AAC blocks and similar porous mineral substrates to improve sealant adhesion. Primer-3N is widely used in Australian facade remediation prior to application of Sikaflex-11FC+ and similar one-part polyurethane sealants on masonry and concrete substrates. It is applied by brush to the clean, dry joint surfaces and allowed to flash off (typically 30–60 minutes at 23°C) before sealant is applied. Do not apply sealant before primer has properly dried — confirm flash-off time from current Sika TDS. Primer-3N is also suitable for use with silicone sealants on porous substrates — confirm from current Sika system guide. Always confirm that the primer is specifically recommended for the sealant product being used and the substrate being primed — not all Sika primers are interchangeable across sealant types. TODO: owner confirm — confirm primer system, flash-off time and substrate compatibility from current Sika TDS and system guide.
Technical Properties
- One-part solvent-based — brush applied
- Suitable for concrete, masonry, render and mortar substrates
- Compatible with Sikaflex polyurethane sealant systems
Limitations
- Not suitable for non-porous substrates (glass, aluminium, UPVC) without a different Sika primer — confirm correct primer for non-porous substrates with Sika technical
- Sealant must not be applied before primer has flashed off — premature sealant application causes adhesion failure
- Do not use as a paint primer or general adhesion promoter for non-sealant applications
PROCUREMENT SOURCES
Always confirm primer with current sealant manufacturer TDS before applying.
Sika Primer-215
Silicone sealant primer — non-porous substrates — aluminium, glass, UPVC
System Description
Sika Primer-215 is a primer designed for non-porous substrates used prior to SikaSil silicone sealant application. It is suitable for priming aluminium (anodised and powder-coated), glass and UPVC window frame substrates to improve silicone sealant adhesion. In facade remediation, Primer-215 is typically applied before SikaSil weatherseal silicone sealant on aluminium window and door frames. Apply by clean cloth, lint-free rag or brush to the clean, dry substrate surface and allow to flash off before applying sealant — confirm flash-off time from current Sika TDS. Always confirm that Primer-215 is the correct primer for the specific SikaSil product being applied and the substrate being primed — consult the current Sika sealant system guide. TODO: owner confirm — confirm primer system, flash-off time, compatibility and substrate requirements from current Sika TDS and technical documentation.
Technical Properties
- Suitable for non-porous substrates — aluminium, glass, UPVC
- Used prior to SikaSil silicone sealant systems
- Flash-off required before sealant application — confirm from current Sika TDS
Limitations
- Not suitable for porous substrates (concrete, masonry) — use Sika Primer-3N for porous substrates
- Must flash off completely before sealant application
- Confirm correct primer for specific substrate and sealant product with Sika technical
PROCUREMENT SOURCES
Always confirm primer with current sealant manufacturer TDS before applying.
Tremco 636 Primer
Universal sealant primer — multi-substrate — PU and silicone compatible
System Description
Tremco 636 Primer is a universal adhesion primer used prior to Tremco sealant applications on a range of substrates including concrete, masonry, mortar, render, aluminium, glass and anodised metals. It is widely specified alongside Tremco sealant systems in Australian facade remediation — including prior to Tremco Vulkem 116 (one-part PU) and Tremco Spectrem 1 (silicone) sealant applications. Tremco 636 Primer is applied by brush or cloth to the clean, dry joint surfaces and allowed to flash off before sealant application — confirm flash-off time from current Tremco TDS. Always confirm that Tremco 636 is the correct primer for the specific sealant product and substrate — consult the Tremco technical representative or current system guide. TODO: owner confirm — confirm primer system, flash-off time, substrate compatibility and current designation with Tremco Australia technical.
Technical Properties
- Universal primer — suitable for concrete, masonry, aluminium and glass substrates
- Compatible with Tremco PU and silicone sealant systems
- Brush or cloth applied to clean, dry substrate
Limitations
- Always confirm primer is specified for the exact sealant product and substrate being used
- Do not apply sealant before primer flash-off is complete
- Do not substitute primer types across different sealant brands without manufacturer confirmation
PROCUREMENT SOURCES
Always confirm primer with current sealant manufacturer TDS before applying.
System Comparison
Sealant primer comparison by substrate type. Always confirm primer with sealant manufacturer TDS before application.
| Primer | Brand | Substrates | Sealant type | Flash-off | Primary use |
|---|---|---|---|---|---|
| Sika Primer-3N | Sika | Concrete, masonry, render | PU, silicone (porous) | 30–60 min — confirm TDS | Porous substrates before Sikaflex PU and SikaSil silicone sealant application |
| Sika Primer-215 | Sika | Aluminium, glass, UPVC | SikaSil silicone | Confirm TDS | Non-porous substrates — aluminium window frames and glazing perimeters before SikaSil silicone |
| Tremco 636 Primer | Tremco | Concrete, masonry, aluminium, glass | PU, silicone (Tremco system) | Confirm TDS | Multi-substrate primer before Tremco PU and silicone sealant systems |
Do not confuse sealant primer with:
- Paint primer or undercoat (architectural paint primers improve paint adhesion — not the same as sealant adhesion primers — do not substitute one for the other)
- Concrete sealer or penetrating sealer (concrete sealers repel water and are designed to prevent adhesion — applying concrete sealer before sealant will cause sealant failure)
- Silane or siloxane water repellent (water repellent treatments on masonry prevent sealant adhesion — sealant must be applied before water repellent treatment, or water repellent must be removed)
- Bond breaker tape (bond breaker tape prevents adhesion — the opposite function to a primer — used on the third face of a joint, never on bonding faces)
- Two-part epoxy adhesion promoter (different product category — epoxy adhesion systems are not primers for elastomeric sealant applications)
Disclaimer
This page provides general technical information only. Always confirm primer selection and substrate compatibility with the sealant manufacturer before application. Incorrect primer selection can cause sealant adhesion failure.