How to remove paint, cement and silicone from new windows

Why new windows end up covered in mess

In Malta, windows and balcony doors are often fitted before plastering, rendering and painting are finished. Unless every pane is properly covered, the glass and frames end up with:

• Paint spots from walls, ceilings and the facade.
• Cement and plaster splashes from rendering, tiling and pointing.
• Silicone smears from sealing frames and bathrooms.
• Fine limestone and cement dust over everything.

These are not hard to remove, but the wrong method can scratch new glass permanently.

The golden rule: wet first, then scrape

Never scrape dry glass. Dry paint and cement are gritty. A blade dragged over dry glass pushes the grit across the surface and leaves fine scratches you will see every time the sun shines through.

Always:

1. Rinse off the loose dust with plenty of water.
2. Soak the spots with soapy water and leave them for a few minutes to soften.
3. Keep the glass wet the whole time you are scraping. If it starts to dry, stop and wet it again.

Check your glass type first

Many modern windows have coatings or special glass that scratch more easily. Before using any blade, check with the window supplier or installer, especially for:

• Coated or low-emissivity glass, which has a thin coating on one face.
• Tinted or reflective glass, or glass with a window film applied.
• Toughened glass, used in doors, balustrades and large panes.
• Decorative, patterned or frosted glass.

If in doubt, use only water, a soft cloth and a plastic scraper, or leave it to a professional.

What you need

• A bucket of warm water with washing-up liquid.
• A sponge or strip washer.
• A glass scraper with a new, sharp blade, for plain glass only.
• A plastic scraper, for silicone and near frames.
• Microfibre cloths and a squeegee.
• Gloves and eye protection.

Removing paint spots

1. Soak the spots with soapy water.
2. Hold the scraper at a low angle to the glass, close to flat.
3. Push it forward in one direction, in short strokes. Do not drag it back and forth.
4. Wipe the blade often, and keep the glass wet.
5. Rinse, then squeegee and dry the glass.

Use a new blade. A nicked or dull blade scratches. Replace it as soon as it starts to catch.

Removing cement and plaster splashes

1. Soak them well. Cement softens with water, though dried splashes may need several soakings.
2. Lift them gently with a wet scraper at a low angle, as above.
3. Do not chip them off dry, and do not use a knife point.
4. Do not use strong acids or brick cleaners. They can damage aluminium and timber frames, rubber seals, and the limestone sills and surrounds around the window.

Removing silicone

1. Cut away the bulk with a plastic scraper, working carefully at the edges.
2. Rub off the thin film that remains with a cloth and soapy water.
3. For stubborn film, ask the window supplier or installer which silicone remover is safe for your frames and seals before using one, and test it on a small area first.
4. Never cut into the frame seals that hold the glass in place.

Frames, tracks and sills

Building mess does not stop at the glass:

• Aluminium and uPVC frames: wipe with soapy water and a soft cloth. Use a plastic scraper for spots. Never use a metal blade on frames.
• Timber frames and gallariji: use a damp cloth only. Scraping can lift paint and damage the wood. See our guide on cleaning Maltese balconies.
• Sliding tracks: vacuum out cement grit and dust before using the doors, or it will grind the rollers. See our guide on cleaning aluminium sliding door tracks.
• Limestone sills: rinse with plain water and a soft brush. Avoid acids.

Common mistakes

• Scraping dry glass.
• Using an old or nicked blade.
• Dragging the scraper back and forth.
• Using a blade on coated, tinted or toughened glass without checking.
• Using scouring pads, steel wool or wire brushes.
• Using acids or strong solvents that damage frames, seals and stone.

Prevention for next time

If you have more building or painting work planned:

• Ask the contractor to cover the glass and frames with protective film or sheeting before rendering or painting.
• Remove the covering as soon as the work is finished, because some tapes and films are hard to remove after weeks in the sun.
• Clean splashes while they are fresh, when they come off much more easily.

Shops and offices near building sites often need more frequent cleaning while the work goes on. See how often to clean a shopfront.

When to call a professional

A post-construction window clean is worth booking when:

• there is a whole house or block of new windows;
• the glass is on upper floors or reached only from outside;
• the windows have coated or toughened glass and you are not sure what is safe;
• there is a lot of cement or paint on the glass.

Professional window cleaners deal with building mess every week and know how to remove it without scratching. clear.mt arranges post-construction window cleaning across Malta and Gozo. See also our guide on cleaning up after building work.