Sill Repair [2021]: Sandstone Window

: Fill hairline cracks with a specialized stone filler or a cementitious epoxy designed for masonry.

| Material | Application | Key Property | | :--- | :--- | :--- | | | Deep fills & rebuilding corners | Breathable, flexible, softer than stone. | | Stone dust / Crushed sandstone | Aggregate for lime mortar | Colour & texture match. | | Ethyl silicate consolidant | Surface hardening (5-10mm depth) | Re-binds silica grains; does not seal surface. | | Pre-mixed stone repair mortar | Small patches (3-15mm) | Usually resin + stone flour; test for hardness. | sandstone window sill repair

You may also see "crusts"—a hard, blackened skin caused by pollution and gypsum formation. While it looks stable, the stone beneath this crust often turns to dust. If you press on a seemingly solid sill and it feels soft or crumbly, you are dealing with deep-seated decay. : Fill hairline cracks with a specialized stone