How to clean sh stains from lead flashing with Oxy Cleanze

September 23, 2023

How to clean sh stains from lead flashing with Oxy Cleanze

When soft washing roofs that have a lot of lead flashing, sodium hypochlorite (sh, hypo) may react with the lead and discolour through oxidation.

At 5:1 Benz LIghtning Cleanze may cause oxidation on lead flashing, as will all sodium hypochlorite based products. At 10:1 it is classified as non-corrosive and is unlikely to affect lead, except – possibly – if applied on a very hot day.

We recommend rinsing lead flashing immediately prior to treating the surrounding area with Benz Lightning Cleanze, keeping the product away from the lead as much as possible by skilful spray techniques, and rinsing again immediately after application.

Rinsing prior to soft washing with any sodium hypochlorite product, rinsing during soft washing, and then a final rinse when the soft wash treatment is complete, will go a long way to protect the lead.

Quick tips:

  • When wetting the lead, there's a possibility of diluting the Lightning Cleanze that's just been applied. If this happens just give the surface a quick extra application by spray or brush.

  • Another option is to treat the render below the flashing first, to give Lightning Cleanze some time to activate before wetting the lead.

Of course sometimes rinsing alone just isn't enough.

That's where Benz Oxy Cleanze oxidation removal gel comes in.

Using Benz Oxy Cleanze oxidation remover to clean lead flashing

New lead has a whitish/blueish appearance that "dulls down" to the grey colour everyone is familiar with.

Oxy Cleanze will quickly remove oxidation stains on lead flashing caused by natural oxidation and soft washing with sodium hypochlorite.

Quick tip: Modern lead may not be pure and so can discolour over time. Benz Oxy Cleanze cannot reverse this form of reaction.


A controlled test using Oxy Cleanze oxidation removal gel to clean lead

We coated the lead in the photo below with neat Lightning Cleanze and left it for 60 minutes. Then we rinsed and dried it. The temperature was 6 ℃.

Lead treated with Benz Blackwash sodium hypochlorite mix

In the photo below we applied Oxy Cleanze rust remover by brush and left it to work.

OxyCleanze oxidation remover applied to lead treated with sodium hypochlorite

The photo below shows the results after only 30 minutes.

Result of treating lead oxidation with OxyCleanze oxidation remover gel

Two hours later we rinsed the Oxy Cleanze gel from the lead.

Oxidation removed after rinsing OxyCleanze from treated lead

The results we achieved would be satisfactory for most lead restoration work, after lead has been cleaned with a sodium hypochlorite based product.

Apply a second coat if needed. In the photo below the far right section was treated a second time. We left this overnight and rinsed the oxidation removal gel from the lead.

Quick tip: It was winter and cold when we ran these tests. We do not recommended leaving a treated surface overnight during the warmer summer months.Benz OxyCleanze oxidation remover applied twice

The photo below shows what the lead looked like when dry. Notice that it looks brighter and more blue/white than the dull grey we are used to seeing on lead flashing.

The treated lead will gradually "dull down" with age (the change of background colour was due to poor lighting conditions).

Oxidation cleaned from lead by Benz OxyCleanze oxidation remover

Click here if you've read enough and want to order Benz Oxy Cleanze


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Using Benz Oxy Cleanze to clean heavily oxidised lead flashing

On the property below, one application of Oxy Cleanze was enough to remove the yellow staining caused by soft washing with sodium hypochlorite, along with some ingrained oxidation.

Yellow staining on lead by sodium hypochlorite and oxidation

After four hours at 5 ℃ we thoroughly rinsed Oxy Cleanze rust removal gel from the lead flashing with ordinary tap water, using a garden hose and some light brushing. The photo below shows the result:

Benz OxyCleanze removes oxidation from lead roof flashing

Quick tip: The deeply ingrained oxidation, which had built up over many years, could not be removed without the repeated use of Oxy Cleanze, which could cause whitening of the lead .

This may be undesirable in some situations and for some customers. So always inform your customer of the possible results of repeated applications of Oxy Cleanze and let your customer make the decision as to whether to go ahead.

Rmove oxidation from lead flashing

Fortunately, natural weathering will reverse the whitening over time. As you can see in the above photo, where the lead flashing is tarnishing and dulling down.

Quick tips:

  • Although multiple applications of Oxy Cleanze may turn lead white, this is normally not a problem when reversing the effects of soft washing with sodium hypochlorite.
  • Oxy Cleanze is less effective on very old oxidation stains.
  • For the best possible job, after treatment with Oxy Cleanze wipe the lead with patination oil.

We hope this information is helpful and sincerely wish you great success in your soft washing business,

Benz Team

Click here to get more practical soft washing how-to tips

How to find answers to most soft washing questions: Simply enter a relevant "keyword" or short phrase – e.g. keyword for the above link = "how to" – into our in-site Search Engine (magnifying glass icon on the main menu).

Click here to download our Product Documentation Pack (includes Application & Dilution guides, SDS, PDS, RAMS, PPE & Mask info, COSSH, sample Contract and more)

Order Benz Softwash chemicals & equipment online or by phone:

GB (England, Scotland, Wales)

Phone: 0800 70 74 222 


Ireland and other countries

Phone: 00353 214 622 978


Lines open Monday - Friday, 9am – 5pm

Please note: The above numbers are for orders only (click here for tech support)

PS: Click here to set up your "Clean & Maintain" programme
. After completing an initial soft wash treatment, put your customer on a "Clean & Maintain" ongoing maintenance programme. Your customers will enjoy a permanently clean property and you will enjoy a steady stream of repeat business.

This is clearly a win-win arrangement for you and your customers.


Click here to explore the extensive range of Benz softwash cleaning chemicals & equipment

Benz Softwash Bio Cleanze DDAC biocide & Benz Softwash Lightning Cleanze SH sodium hypochlorite biocide

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