ShelfYears

Does spray foam expire?

DuPont prints an expiration date on the bottom of the can and rates GREAT STUFF between 12 and 18 months depending on the product — and a can that has already been used is measured in days, unless it is sitting on a dispensing gun.

Updated

Spray foam
Sealed
12–18 months
Opened
30 days on a gun
CURE-IN-CAN & PRESSURE LOSS
Degraded performance

Sealed: 12–18 months Tier 1

DuPont's product information sheet for GREAT STUFF PRO Gaps & Cracks gives a shelf life of 18 months for the straw version when stored at 75°F. The consumer GREAT STUFF Wide Spray sheet gives 12 months at the same temperature. Both cans carry a printed expiration date on the bottom, because past it the contents may have cured inside the can and will simply not come out.

By manufacturer — the disagreement is information
Brand Sealed window
GREAT STUFF Wide Spray 12 months at 75°F
GREAT STUFF PRO Gaps & Cracks (straw) 18 months at 75°F

After opening: 30 days on a gun Tier 1

DuPont publishes the opened figure and it is short: the PRO cans are reusable for 30 days when left attached to a GREAT STUFF PRO dispensing gun, because the gun makes an airtight, moisture-tight seal between itself and the can. A straw can has no such seal. Once the straw has foam in it and the trigger has been released, the straw sets solid, and the valve behind it is exposed to the same humid air.

How to tell it's gone off

  • Check the expiration date on the bottom of the can — DuPont prints one because the contents may not dispense after it.
  • Foam that comes out as a thin, wet stream and never expands.
  • A straw or gun tip blocked by cured foam that cannot be cleared.
  • A can that has lost its hiss, or one that feels heavy and dead when tipped.
  • Foam that stays sticky far past the tack-free time printed on the can.

If you use it anyway

Degraded performance

An expired can of foam mostly refuses to work, and it tells you in the first second of the trigger pull. DuPont's own wording is that past the date the contents may have cured and be unable to spray; short of that you get a thin bead that will not expand and will not seal a gap. What it costs is the trip for a fresh can.

Why it goes off — CURE-IN-CAN & PRESSURE LOSS

The contents of the can are a single-component polyurethane that cures on the moisture it meets in the air — the same reaction that turns the bead rigid on the wall. Inside a sealed, pressurized can there is no moisture to react with, so the clock runs slowly and DuPont can print a date. Once the valve has been opened, humid air reaches the resin at the tip, cures it, and the plug works backwards. Separately, the propellant that pushes the foam out bleeds away past a used valve, so an old part-used can can be full and still deliver nothing but a thin, unexpanded stream.

Every page here commits to one of four states — Harmless · Degraded performance · Equipment damage · Safety issue. How the verdicts work.

How to store it

DuPont's storage sentence carries the number: 18 months for a straw can stored at 75°F, with the instruction not to puncture, incinerate or store at temperatures above 120°F. The can is under pressure and DuPont warns it may burst if left where things get hot — a vehicle, or near a radiator or stove. Store it upright, indoors, at room temperature, and if it is on a dispensing gun, count 30 days from the day it went on.

Never puncture a foam can, and never store one above 120°F or in a hot vehicle.

Sources