Sealants for Food Processing & Cold Storage Facilities
NSF compliance, temperature requirements, and material selection for food processing facilities
Last updated: June 1, 2026
Quick Reference
Most common applications and what works:
Walk-in freezers & cooler panels
Use silicone sealant. Stays flexible to -60°F, handles the temperature swings when doors open and close.
Processing equipment seals
Need NSF-51 certified sealant for direct food contact. Check your HACCP plan.
Floor joints in production areas
Polyurethane sealant works best. Can handle forklift traffic and takes a paint or epoxy topcoat.
Wash-down zones (walls, ceilings)
Mold-resistant silicone sealant. Chemical resistant to facility cleaners.
Ovens, steam lines, hot areas
High-temp silicone sealant rated for your specific temperature. Most handle 400°F+.
NSF Certifications
If you're working in food processing, NSF certification matters. Here's what the different ratings mean:
NSF-51 Certified
Direct food contact zones. Tested for non-toxicity and won't leach chemicals into food. Required in areas where sealant might touch food or food contact surfaces.
Common locations: Processing equipment seals, conveyor systems, food prep surfaces
NSF-Listed (Non-Food Contact)
Splash zones and indirect contact areas. Tested for food facility use but not meant for direct food contact. Covers most of your facility.
Common locations: Walls, floors, drains, HVAC penetrations, walk-in coolers
Most facilities need both. Use NSF-51 where required by code or your HACCP plan, and NSF-Listed everywhere else in the processing environment.
NSF-51 Certified Sealants
Silicone vs Polyurethane
Both work in food facilities, but they're good at different things.
| Property | Silicone | Polyurethane |
|---|---|---|
| Temperature range | -60°F to 400°F+ | -40°F to 200°F |
| Movement capability | ±50% (excellent) | ±25% (good) |
| Chemical resistance | Very good | Excellent |
| Paintable | No | Yes |
| Best for | Freezers, ovens, temp swings | Floor joints, high-traffic |
Rule of thumb: Use silicone where temperature varies a lot. Use polyurethane for floors and areas that need paint or epoxy topcoat.
Cold Storage
Walk-in coolers and freezers fail for two reasons: wrong sealant or no backer rod.
Application temperature vs. service temperature
This is the mistake that ruins cold-storage jobs. A sealant's service temperature — how cold the cured bead survives, often -60°F for silicone — is not the same as its application temperature, the surface temperature you're allowed to apply it at. Most silicones can't be applied below about +40°F, and even many industrial-grade silicones bottom out near +10°F, despite surviving -60°F once cured.
If you're caulking inside an operating freezer or a cold box that hasn't been warmed up for the work, use a silicone specifically rated for low-temperature application (down to roughly -25°F) on a clean, dry, frost-free surface. Expect a much slower cure in cold, dry air, and keep the bead undisturbed until it fully sets. If the box can be powered down and warmed for the job, your sealant options widen considerably.
What happens in freezers
- Thermal cycling: Joints expand and contract with every freeze-thaw cycle
- Moisture infiltration: Warm humid air meets cold surfaces, condensation gets in cracks
- Ice expansion: Any water in the joint freezes and pushes the sealant out
Requirements
- Stays flexible below -40°F (silicone is your best bet)
- High movement capability (±50% minimum for freeze-thaw)
- NSF-Listed for food facility use
- Proper joint design with backer rod (prevents three-sided adhesion)
What to use
For freezer panels and walk-in coolers: NSF-Listed silicone sealant. Look for products rated to at least -40°F with ±50% movement capability.
For floor joints: If you're sealing expansion joints in a freezer floor, polyurethane sealant can work IF the temp stays above -20°F and you need paintability. Below that, stick with silicone sealant.
Don't forget backer rod: Get closed-cell foam backer rod that's about 25% larger than your joint width. This is critical in cold storage to prevent three-sided adhesion.
See the main Sealant Guide - Silicone Section for more details on cold-temperature applications
High Temperature
Ovens, smokers, steam cleaning areas, and anywhere above 200°F.
Temperature ratings matter
- 200°F-350°F: Standard high-temp silicone works
- 350°F-500°F: Need RTV silicone rated for continuous high heat
- 500°F+: Specialized ceramic-filled or high-temp RTV
Don't use polyurethane above 200°F. It'll break down. Silicone or high-temperature specialty sealants only.
What to use
For most ovens and smokers (300°F-400°F): Red high-temp silicone sealant. Red is a common color for high-temp silicones (gray and black are also typical), which can help inspectors spot the right product on the wall.
For steam lines or intermittent spikes above 400°F: Look for RTV silicone sealant specifically rated for continuous high heat. Check the product spec sheet for the exact temperature rating.
Common mistake: Using "high-temp" caulk from the hardware store that's only rated to 250°F. Always check the continuous operating temperature, not just the peak.
For ovens, smokers, kitchen exhaust hoods, and any joint above 200°F that also needs to be food-safe, see the dedicated High-Temperature Silicone Sealant Selection Guide. Both Everkem high-temp products (TruSil 100 at 400°F and Hi-Temp / TruSil HTS at 500°F continuous) are NSF-51 certified for food contact once cured.
Sanitary Wash-Down
Areas that get hosed down daily with hot water, sanitizers, and pressure washers.
What fails in wash-down zones
- Poor surface prep (water gets behind the sealant)
- Wrong sealant type (some break down with chlorine or quaternary ammonia cleaners)
- Mold growth (water trapped in poorly designed joints)
Requirements
- Mold and mildew resistant (most silicones have this)
- Chemical resistance to facility cleaning agents
- NSF-Listed minimum, NSF-51 if near food zones
- Smooth finish (no texture for bacteria to hide in)
What to use
For walls and ceilings in wash-down areas: Mold-resistant silicone sealant with chemical resistance. Most kitchen/bath silicone sealants have mildewcide, but verify it can handle your facility's specific cleaners.
For cove base and floor-to-wall joints: If you're in a high-traffic zone that gets painted or sealed with epoxy, use polyurethane sealant. Otherwise, silicone sealant gives better long-term mold resistance.
Testing tip: If you're switching cleaning products, test your sealant with a sample first. Some quaternary ammonia cleaners can degrade certain silicone sealants over time.
See the main Sealant Guide - Silicone Section for mold-resistant options
Compliance Checklist
Before you seal, check these requirements:
- NSF certification matches your zone (NSF-51 for food contact, NSF-Listed for splash zones)
- Temperature rating covers your min and max operating temps
- Chemical compatibility with your cleaning protocols
- Movement capability matches joint design (Class 25 minimum, Class 50 for thermal cycling)
- Surface prep is clean and dry (primer if needed)
- Backer rod sized correctly (25% larger than joint width)
- HACCP plan reviewed (if applicable to your facility)
Most inspection failures come from using the wrong NSF rating or skipping surface prep. Get these two right and you're ahead of 80% of problems.
Frequently Asked Questions
Can you apply silicone sealant inside a cold or operating freezer?
Only if it's rated for low-temperature application. The number that matters is the application temperature, not the service temperature. Most silicones survive -60°F once cured but can't be applied below about +40°F, and even many industrial silicones bottom out near +10°F. To caulk inside an operating freezer (or a cold box that hasn't been warmed up), use a silicone specifically rated for low-temperature application — down to roughly -25°F — on a clean, dry, frost-free surface. Expect a much slower cure in cold, dry air, and protect the bead from movement until it fully sets. If the freezer can be powered down and warmed above the sealant's minimum application temperature for the work, your options widen considerably.
Should I use silicone or polyurethane sealant in a freezer?
Use silicone for freezers and cold storage. Silicone maintains flexibility below -40°F and handles thermal cycling better with ±50% movement capability. Polyurethane only works down to -40°F with ±25% movement capability and is best reserved for floor and expansion joints.
What is the difference between NSF-51 and NSF-Listed sealants?
NSF-51 certified sealants are tested for direct food contact and non-toxicity, required where sealant might touch food or food-contact surfaces. NSF-Listed sealants are for splash zones and indirect-contact areas — they cover most of a food facility but aren't meant for direct food contact. A freezer or cooler wall is typically a splash/non-contact zone, so NSF-Listed is usually sufficient there; use NSF-51 wherever sealant can reach food or food-contact surfaces.
What is the difference between NSF-51 and FDA compliant sealants?
FDA compliance (21 CFR 177.2600) means the sealant's ingredients meet FDA requirements for repeated food contact. NSF-51 certification means the finished product has been independently tested and certified by NSF International for direct food contact use. A sealant can be FDA compliant without NSF-51 certification, but most food facility inspectors, dairy auditors, and HACCP plans require NSF-51 because it provides third-party verification. When in doubt, specify NSF-51 — it satisfies both requirements.
What are the best chemical resistant sealants that are FDA compliant for dairy equipment?
For dairy equipment seals exposed to CIP (clean-in-place) chemicals like caustic soda, phosphoric acid, and peracetic acid, use an NSF-51 certified silicone rated for continuous exposure to both acidic and alkaline solutions. Silicone outperforms polyurethane in dairy because it resists the thermal cycling of pasteurization (hot CIP at 160°F+ followed by cold rinse) without cracking. For FDA compliance, verify the sealant meets FDA 21 CFR 177.2600 (rubber articles for repeated food contact) and carries NSF-51 — the standard most inspectors and dairy auditors check. The NSF-51 silicones we stock, Everkem TruSil 100 and Hi-Temp Heat Resistant Silicone, are Made in USA and certified to both.
Can I use polyurethane sealant in a food processing facility?
Yes, but only in specific locations. Polyurethane works well for floor joints, expansion joints, and areas that need to accept paint or epoxy topcoats. However, polyurethane degrades faster than silicone when exposed to repeated chemical wash-down, breaks down above 200°F, and has less movement capability (±25% vs ±50% for silicone). For direct food contact, cold storage, high-temp, or dairy CIP zones, silicone is the better choice.
What temperature rating do I need for commercial oven sealants?
For 200-350°F use standard high-temp silicone. For 350-500°F use RTV silicone rated for continuous high heat. Above 500°F requires specialized ceramic-filled or high-temp RTV sealants. Never use polyurethane above 200°F. Always check the continuous operating temperature, not just the peak rating.
What causes sealant failure in wash-down areas?
Most failures come from poor surface prep (water gets behind the sealant), using the wrong sealant type that breaks down with chlorine or quaternary ammonia cleaners, or mold growth from water trapped in poorly designed joints. A mold-resistant silicone with a smooth, properly tooled finish prevents most of these.
How do I know if my sealant is compatible with my facility's cleaning chemicals?
Check the sealant manufacturer's chemical resistance chart for the specific chemicals in your CIP or sanitation protocol. Common food facility chemicals include sodium hydroxide (caustic), phosphoric acid, peracetic acid, chlorine-based sanitizers, and quaternary ammonium compounds. Silicone sealants generally resist all of these. Polyurethane resists most but degrades faster with concentrated caustic or chlorine. If you use an unusual sanitizer, request a compatibility letter from the sealant manufacturer before specifying.
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