Using Koch Chemie Glas Star: undiluted or diluted 1:3

Koch Chemie Glas Star is a concentrated, alcohol-based glass cleaner. Use it undiluted for heavy soiling or diluted 1:3 with osmosis water for daily maintenance, where 1 litre makes 4 litres of cleaner. The formula removes oil, grease, silicone, insects, wax residue and overspray streak-free. A gloss additive lets the cloth glide smoothly over the glass and the alcohol dries fast, even in cold weather.

Undiluted or diluted 1:3

For stubborn dirt, greasy film or insect residue, use Glas Star undiluted for the most cleaning power. For a regular maintenance wipe, dilute 1 part Glas Star with 3 parts osmosis or de-ionised water. Tap water contains limescale that can leave streaks itself, so for the best streak-free result use low-mineral water to dilute.

How to use it

Dilute 1:3 with osmosis or de-ionised water for maintenance, or use Glas Star undiluted for heavy soiling.
Spray Glas Star onto the window or onto a clean, lint-free microfiber cloth. Do not work on a hot window in direct sun, as the cleaner dries in too fast.
Wipe the glass in straight passes so you can see which part you have covered. The gloss additive lets the cloth glide and prevents cloth-drag streaks.
Buff with a second, dry microfiber cloth for a streak-free, crystal-clear result.

Why a concentrate

Because you dilute 1:3, 1 litre of Glas Star makes four litres of ready-to-use cleaner, which makes it economical for regular use. The gloss and smoothness additive reduces cloth friction, and the alcohol base flashes off quickly so you get fewer streaks and can work well even in winter. Always use a clean, lint-free glass towel for the best result.

What you use Glas Star on

Glas Star works on smooth, alcohol-resistant glass: front and rear windows, side windows, exterior and interior mirrors and headlight glass. The inside of the windscreen, where a greasy haze of outgassing and nicotine builds up, also comes clear with it. Besides car windows, Koch Chemie names truck glass and building glass as applications, so the same bottle serves your car, van and workshop. On coated screens and sensitive surfaces, always test on a small spot first.

What Glas Star does not do

Glas Star removes grease, dirt and film, but not dried limescale or water spots; those are mineral deposits you have to tackle separately. For that, read the guide on removing water spots and limescale.

Do I use Glas Star undiluted or diluted?

Undiluted for heavy soiling, greasy film or insect residue. For daily maintenance, dilute 1:3 with osmosis or de-ionised water, where 1 litre makes 4 litres.

Which water do I use to dilute?

Preferably osmosis or de-ionised water. Tap water contains limescale that can leave streaks or spots itself, so low-mineral water gives the best streak-free result.

Is Glas Star safe on tinted glass or film?

Glas Star is not specifically labelled as tint-safe. Always test on an inconspicuous spot of the window film or tinted glass first, spray the cloth instead of the film directly, and avoid letting liquid soak along the edges. If you are unsure about compatibility with your film, use a product that is explicitly made tint-safe.

Does Glas Star remove water spots and limescale?

No. Glas Star tackles grease, dirt and film, but not dried mineral limescale. For water spots you need a limescale remover or a glass polish.

Why is there a gloss additive?

The gloss and smoothness additive lets the microfiber cloth glide smoothly over the glass. That reduces friction and prevents the typical cloth-drag streaks you get when a cloth keeps catching.

Can I use Glas Star on the inside of the windows too?

Yes. Spray the cloth instead of the glass directly, so no liquid runs into the edges or onto screens, and buff with a dry cloth for a clear inner window.