Use Benz Lightning Cleanze to prepare surfaces for painting, including previously painted surfaces.
Kill the algae and other biological growth, then rinse away the dead growth, cobwebs and surface debris to leave a clean surface ready for painting or repainting.
If you are cleaning STO render, do a small test area first. It may not come perfectly clean without steaming, but it will often come clean enough to repaint.
Sand and cement render needs a different approach. Read our guide to soft washing painted sand and cement render.
Is Lightning Cleanze safe on paintwork?
Professional painters use Lightning Cleanze to pre-clean surfaces before painting, and we have received no reports of damage to paintwork.
Our own testing and on-site experience since 2013 also show that it does not damage sound paintwork when used correctly.
Lightning Cleanze rinses quickly and easily, and it has never caused paint failure in our experience.
Learn more about Benz Lightning Cleanze
What if your customer says the paintwork now needs repainting?
Explain this clearly before you start: soft washing does not create pre-existing damage, but it can reveal it.
When you remove dirt, algae and staining, the true condition of the paint becomes visible. If the paint was already failing, the cleaning process simply exposes that.
Warn your customer in advance that pre-existing defects may become more visible after cleaning.
Take clear close-up before photos before you start. If a customer later questions the result, you can refer back to the condition that was already there.
How to clean painted through-colour render
Check the surface carefully and ask the customer exactly what has been done before you start.
Sometimes you will find through-colour silicone render that has already been painted. This is uncommon, and peeling paint is often the giveaway.
Prepare painted through-colour render properly before repainting. Use Lightning Cleanze and, where appropriate, follow with Bio Cleanze to reduce the risk of algae growing back under the new paint.
Quick tip: Paint through-colour render such as KRend only with a specialist coating designed for that purpose.
KRend recommends Rendit as a paint supplier. They specialise in render paints and can colour-match KRend finishes.
Learn more about painting through-colour render
Pre-cleaning render with Bio Cleanze
If your customer does not want you to use a sodium hypochlorite product, pre-clean the surface with Benz Bio Cleanze.
Once the surface dries, you can paint over it, but you still need to remove the dead biofilm and loose debris before painting.
After about a month, much of the dead biofilm will have weathered away through sun, wind and rain. Even so, rinse before painting to remove dust, loose growth and cobwebs.
Results vary depending on:
- The local environment
- The time of year
- How much sun and rain the surface receives
- The depth of colonisation
- How long the growth has been present
Bio Cleanze works faster in warm weather, but results can still take anything from a few days to several months depending on the surface and the contamination.
Quick tip: Use Bio Cleanze where its wetting ability can penetrate the surface, kill deeper-rooted growth and give longer residual protection.
Do not rely on that same deep-penetration effect on non-porous painted surfaces. On those surfaces, use Lightning Cleanze as your main cleaner and bring in Tornado Cleanze where stubborn staining remains.
Learn more about soft washing render
Read our general guide to soft washing render
Read more detailed guidance on specific render-cleaning topics
Explore the Benz soft-washing how-to manual
Quick tip: Some painted render already has algae growing beneath the paint because the surface was never cleaned properly before painting. You may only fully see that when you kill and remove the surface growth.
If that happens, explain that the problem sits under the coating. In many cases, the only proper fix is to strip the paint, treat the contamination, and repaint correctly.
Explain this risk before you start. When the customer understands the possible outcome in advance, they are far less likely to blame the cleaning process for hidden defects that were already there.
Read more practical Trade Tips on cleaning painted surfaces
Use the on-site search engine to find answers to specific softwash questions.
Download the Product Documentation Pack for application and dilution guides, SDS, PDS, RAMS, PPE and mask guidance, sample COSHH information and more.
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