§ THE TOOLS  ·  01 / 09  ·  SIGNATURE  ·  MOST USED

The Streak Diagnostic.

Two questions, one verdict. Identify what is actually wrong with your window — and find the article that walks you through the fix.

Maps to twelve diagnoses across the Diagnostician pillar.

QUESTION 1 OF 250% COMPLETE

Where is the problem on your window?

the location is the single biggest diagnostic clue

The first split: surface haze vs. between-pane fog vs. edge-specific damage. Most homeowners skip this question and go straight to "what cleaner do I need?" — which is why most homeowners reach for the wrong cleaner.

Surface haze, streaks, or film across the glass

Whatever it is, it covers the visible glass area. Usually wipes off when wet, comes back when dry.

Inside the pane — I cannot wipe it off either side

Cleaning the interior and exterior surfaces does nothing. The haze is sealed inside the unit.

Discrete spots, dots, or droplet marks

Not a continuous haze. Distinct individual spots, often clustered.

Only at the edges, gasket, or frame area

Center of the glass is clear. The problem is concentrated where glass meets frame.

Scratches, gouges, or visible mechanical damage

Not chemical or biological — actual lines or marks in or on the glass.