ASTM E2190, IGU seal durability
Any IGU looks perfect the day it ships. The real question is whether it will still be clear and gas-tight in fifteen years, and that is what ASTM E2190 exists to predict. It ages units on purpose with heat, humidity, and UV, then checks for seal failure, dew point, and fogging. It is also the backbone of IGMA certification.
Why IGU seal durability matters
When an IGU loses its seal, you lose twice over. The argon leaks out and the thermal performance quietly drops, so the unit stops doing the job it was specified for. Then moisture works its way in and fogs the cavity. That haze sits on surfaces 2 and 3, on the inside of the unit, where nobody can ever clean it. The only fix is a new unit.
This is the most common IGU warranty claim there is, and the main reason units get pulled out of buildings long before anyone budgeted to touch them. Which leaves an awkward problem: you cannot wait fifteen years to find out whether a seal design works. That is the gap E2190 fills. It ages units on purpose, in a lab, under conditions rougher than any real wall, and sees what is still intact at the end.
Test program overview
The test does not simply bake units and hope. It runs them through a sequence of stresses, each one picked because it mirrors a specific way seals die in the field:
| Test phase | Conditions | What it evaluates |
|---|---|---|
| High humidity cycling | Exposure to elevated humidity at elevated temperature; alternating with ambient conditions | Primary seal (PIB) resistance to moisture vapor drive; sealant adhesion under wet conditions |
| UV exposure | UV radiation on the exposed edge sealant | Silicone or polysulfide secondary seal UV resistance |
| Temperature cycling | Repeated cycling from cold to hot temperatures | Sealant flexibility and bond durability under thermal movement |
| Pressure equalization | Barometric pressure variation | Spacer seal integrity under pumping stress from pressure differentials |
Acceptance criteria
Survive all of that, and the unit still has to pass two final checks. Both are simple pass or fail, and neither leaves much room to argue:
- The interior gas space is cooled until condensation forms (or fails to form) on the interior glass surface
- Acceptance criterion: dew point ≤ -40°F (-40°C) after weathering
- Indicates desiccant is still functioning and moisture infiltration is minimal
- Interior surfaces of the unit are inspected under controlled illumination for deposits
- Failed seals allow volatile organic compounds from sealant or desiccant to migrate to interior glass surfaces and deposit as haze
- Acceptance: no visible deposits on the interior glass surfaces
Relationship to IGMA certification
E2190 is the test. IGMA certification is what turns a passed test into something you can lean on when you are writing a spec. The Insulating Glass Manufacturers Alliance makes member fabricators test their unit configurations to E2190 (or the Canadian equivalent, CAN/CGSB 12.8), then audits how they actually build them day to day. When a unit carries the mark, three things are true:
- That exact build, meaning the glass type, spacer, primary seal, secondary seal and desiccant together, went to a third-party lab and passed E2190.
- The fabricator gets audited without warning, to check that what comes off the line still matches what was tested.
- You get a paper trail. The mark is traceable documentation you can point at for warranty and spec compliance, rather than a claim in a brochure.