Walk into a Victorian glasshouse on a bright morning and the light does something modern glass simply cannot. Old cylinder and float glass carries a faint ripple, a slight green at the edge, the occasional bubble frozen in place a century ago. It is part of the charm, and it is worth protecting. The trouble is that people tend to treat hundred-year-old glazing like a kitchen window, and that is exactly how panes get cracked, putty gets stripped, and frames start letting the weather in.

None of this is hard. It just asks for a slower, more deliberate approach than the average spray-and-wipe. Here is the routine we walk owners through.

Why old glass needs a gentler hand

Two things set antique glazing apart. First, the glass itself is thinner and less uniform than a modern pane, so it flexes and cracks under pressure that newer glass would shrug off. Second, it is almost never held in by rubber gaskets. It sits in a bed of linseed-oil putty and a few glazing points, and that putty is doing real work — sealing the joint and cushioning the glass against the frame. Disturb the putty and you have disturbed the whole system.

A cleaning routine that won’t do damage

You can keep antique glass beautifully clear without a single harsh chemical. This is the order we use:

1. Dry-brush first. A soft brush lifts grit and cobwebs so you are not grinding dirt across the surface with a cloth.
2. Wash with warm water and a drop of plain dish soap. Skip ammonia and anything labelled “industrial” — it eats old putty and clouds the glass over time.
3. Wipe with a soft microfibre cloth, working with light pressure and flat palms, never a knuckle in one spot.
4. Dry the putty line, not just the glass. Standing water on the seal is what rots it from the outside in.

Glazing putty: the part everyone forgets

Putty is the unsung hero of any glasshouse. When it is sound, the glass stays bedded, sealed, and quiet in a wind. When it dries out and crumbles, the pane starts to rattle, water creeps behind it, and the frame underneath begins to rot. The good news is that re-puttying a single joint is straightforward; the catch is matching the work to the original so it looks right and seals properly.

Tick through these and you will know where your glazing stands:

• Putty lines are smooth and continuous, with no flaking or gaps.
• No pane rattles or shifts when a door slams or the wind gusts.
• No daylight or draught is visible around the edge of any pane.
• The frame timber or metal beneath the glass is dry and firm, not soft.

Repair or replace? How we decide

A surprising amount of old glass can be saved. A clean, stable crack that is not spreading and sits well within the frame will often live happily for years once the putty around it is renewed. What we replace are panes that are loose, badly shattered, or letting weather into the structure — because at that point the glass has stopped doing its job and started costing you the frame.

When a pane really is past saving, that is where careful glass garden repair earns its place — matching the right glass weight, re-bedding it in fresh putty, and leaving the frame weather-tight again rather than just dropping in whatever sheet happens to fit.

Questions we get asked a lot