Butyl Compound Grade Selection Guide: HY, CN, and SD Series Compared

A butyl rubber compound is not a single product — it's a family of formulations tuned for different end uses. Three design axes drive the choice: specific gravity (determines filler loading and cost), peel strength (determines adhesion to substrates), and special additives (flame retardants, tack modifiers, colorants). Picking the wrong grade leads to either overspec'ing (paying for filler you don't need) or underspec'ing (membrane failure, peel loss, code non-compliance).

Garmy manufactures six core butyl compound grades. Each is optimized for a specific downstream converter: self-adhesive waterproofing membrane producers, flame-retardant membrane fabricators for rail and commercial roofing, and butyl sealant tape slitters. Understanding the distinction lets procurement engineers specify CoA (Certificate of Analysis) parameters with confidence.

• Specific gravity (SG) — Higher SG means heavier filler loading (CaCO3, carbon black). Affects weight per square meter, extrusion rheology, and cost per kilo
• Peel strength — Measured in N/cm or per ASTM D903. Determines long-term adhesion under thermal cycling and substrate movement
• Heat/cold tolerance — All Garmy grades operate from -40°C to +110~120°C, but the upper limit varies with the tackifier system
• Regulatory compliance — Flame retardancy (UL94 V-0), low-VOC, halogen-free — only specific grades carry these certifications

Before comparing individual grades, confirm the substrate (PE film? HDPE? metal? glass?) and service condition (exposed roof? cavity wall? IGU spacer?). These two questions drive 80% of the grade decision.

The HY (Heavy-duty Yield) and CN (Construction/Non-exposed) series are formulated for self-adhesive bituminous-alternative waterproofing membranes. These roll goods are applied cold to concrete decks, foundation walls, and green roof substrates. The compound itself is the adhesive — no separate primer or torch is required.

1. Choose HY-1 when peel strength is the governing spec — exposed rooftop applications, high wind uplift zones, large-format membrane where adhesion failure propagates fastest
2. Choose HY-2 when total system weight and thickness matter more than peak peel — pedestrian deck membranes, plaza waterproofing under concrete topping, weighted ballast systems
3. Choose CN-1 for standard below-grade and concealed waterproofing where CN-1's 62 N/cm peel is more than adequate at lower cost
4. Choose CN-FR when the project specifies UL94 V-0 flame retardancy — rail tunnels (EN 45545), plenum installations, high-rise commercial roofs under strict fire codes

Garmy manufactures all four HY/CN grades in-house with consistent batch-to-batch CoA verification under IATF 16949 and ISO 9001 quality systems.

SD-1 and S-3 are formulated specifically for slitting into butyl waterproof tape. The performance targets are different from membrane compounds: tape compounds must retain tack after liner removal, deform plastically to fill substrate irregularities, and stay cohesive enough to be die-cut or slit without stringing.

Note that SD/S series heat resistance tops out at 110°C rather than 120°C. This is deliberate — tape compounds use softer tackifiers that would extract and migrate at higher temperatures. In practice, 110°C is well above any rooftop or cavity-wall service condition, and the trade-off yields dramatically better initial tack and compression seal.

• SD-1 selection cues — Higher peel (42 vs 37 N/cm) when tape sees wind-driven rain, repeated thermal cycling, or substrate movement (e.g., metal roof standing seam, window fin flashing)
• S-3 selection cues — Cost-optimized grade for lower-stress applications: HVAC duct seams, light commercial roofing, electrical enclosure gasketing
• Both grades — Sheet form (PE/PET release liner), roll widths 15–300 mm, thickness 1–3 mm, custom die-cut shapes for OEM
• Do not substitute — Do not use HY or CN compounds directly as tape. Their higher peel comes with higher green strength, making them difficult to unroll and conform to substrate without pre-heating

Garmy supplies SD-1 and S-3 both as raw compound (for converters) and as finished butyl tape in standard widths and thicknesses.

Q: Can I use a single grade across multiple product lines?

A: In principle, HY-1 could serve as a universal compound — its 81 N/cm peel and 120°C heat resistance cover nearly all applications. In practice, this is rarely cost-effective. For non-exposed membranes, CN-1 delivers 60+ N/cm peel at ~20% lower cost. For tape, HY-1's high green strength makes slitting and application harder, so SD-1 is preferred despite its lower peel rating.

Q: How does CN-FR achieve UL94 V-0 without halogenated flame retardants?

A: Garmy's CN-FR uses an aluminum trihydrate (ATH) and phosphate ester system to achieve V-0 rating without halogens. This matches the trend in European rail (EN 45545) and North American construction markets toward halogen-free fire performance. Full flame retardant CoA and SDS available on request.

Q: What's the minimum order quantity for custom-formulated compound?

A: Standard grades ship in 20 kg PE bags on 1,000 kg pallets, with 1-pallet minimum for trial orders. Custom formulations (color match, tackifier adjustment, filler modification) typically require a 2-ton minimum for mixer economics and can be qualified in 4–6 weeks including lab samples and pilot batches.

Q: Do Garmy's compound grades meet ASTM D2000 classification?

A: Yes, all Garmy butyl compounds can be classified per ASTM D2000 callouts. HY series typically falls under AA-class (butyl) with hardness and heat aging requirements documented in the CoA. For OEM specifications referencing specific D2000 line callouts (e.g., AA-710), submit the full spec and Garmy's technical team will confirm match or propose the closest grade.

Q: Which grade should I start with for a new waterproofing membrane product?

A: For a first development cycle, request samples of HY-1 (premium), CN-1 (standard), and CN-FR (flame-retardant). This trio lets you validate downstream processing on three different SG points and confirms whether your end market requires the FR variant. Most converters settle on a 2-grade portfolio after market testing.

Ready to source the right butyl compound for your application?