Short answer: for black spots in silicone and cement joints (discolouring organisms), apply stone clear SE 64 Grout Cleaner undiluted with a brush, leave for 20–30 minutes, scrub with water and a brush and rinse off. For grey, dirty cement grout, apply ZR 66 Cement Grout Cleaner generously, leave for 10–15 minutes and scrub with a grout brush.
Black or grey? The cause decides
| Problem | Typical for | Product |
|---|---|---|
| Black, dark dots and spots | Shower, bathtub, silicone joints, damp corners | SE 64 Grout Cleaner |
| Evenly grey, dirty grout | Kitchen and entrance floors, wall tiles | ZR 66 Cement Grout Cleaner |
Guide: cleaning black grout with SE 64
- Wear safety goggles and rubber gloves, ventilate well.
- Apply SE 64 undiluted to the joints with a brush.
- Leave for approx. 20–30 minutes.
- Scrub with water and a brush, e.g. the RG 938 Grout Brush with Hand Grip.
- Wash off with water. Repeat if necessary.
Coverage: 1 litre for approx. 30–50 running metres of joint.
Caution: SE 64 contains active chlorine and bleaches. Never mix with acidic products. Protect textiles, metals and wood from splashes. Immediately wash splashes off plants with plenty of water. Test in an inconspicuous spot first.
Guide: cleaning grey cement grout with ZR 66
- Dosage: heavy soiling undiluted, normal soiling 1:1 with water.
- Apply generously to the joints with a sponge or brush.
- Leave for approx. 10–15 minutes.
- Scrub with a hand pad or the RG 939 Grout Brush with Handle – that way you can do floors standing up.
- Rinse well with clean water.
Coverage: 1 litre for approx. 50–60 running metres of joint. The joints become hygienically clean and even in colour again.
Tips for keeping joints clean longer
- Squeegee the walls after showering and ventilate well.
- Clean regularly rather than rarely and intensively.
- For natural stone in the shower, only remove limescale acid-free, e.g. with UR 27.
Frequently asked questions
What helps against black silicone joints in the shower?
SE 64 Grout Cleaner: apply undiluted, leave for 20–30 minutes, scrub, rinse. If the discolouration is deep in the silicone, the silicone joint may need replacing.
Can I use grout cleaner and descaler together?
No. Chlorine-based cleaners such as SE 64 must never be mixed with acidic products or used directly one after the other. Always rinse thoroughly with water in between.
Can I use ZR 66 on natural stone?
ZR 66 is made for cement joints. Where natural stone is adjacent, always test in an inconspicuous spot first.
How do I clean floor joints without bending down?
With the RG 939 grout brush with handle. The V-shaped bristles reach perfectly into the joint.
Questions?
Call us: +41 41 790 38 05 or write to us via the contact form.
