Brick Cleaning

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Guest (not verified)
Brick Cleaning


I found you site researching Neolith 39N. Thanks for offering to give advice, its very kind.

I've got a yellow brick victorian terrace in north London. I'll have some scaffolding up in a few months for some roof work and I thought it might be a good opportunity to clean up the bricks at the front of the house.

Theres not much info on doing this DIY on the internet. Most things I could find were warning that using the wrong method will ruin my brickwork. I did however find on some forum talk of flow plant chemicals. Looking at their site and yours it seems that "Neolith 39N" might be a good option for me. But it would be good to know if its strong enough -or if theres a safer option even.

Any help appreciated.



Clement (not verified)
Neolith 39N is one of the most gentle chemicals to use.

Hi Michael,

Yes, your concern is valid - being one of the softest chemicals, Neolith 39N might not suffice for severely dirty surface. What sort of dirt do you want to clean - general dirt, carbon deposits from a nearby highway, oily patches?
Feel free to send us a picture to our general E-mail and I should be able to tell if you need something stronger. In some cases we have good results without using any chemicals, but using hot steam jet wash (not the cold one you have in car washes or a household jet wash).

Best Regards,

Guest (not verified)
Pictures attached

Hi Clement.

Thanks for replying on the forum - and for offering to look at some photos.

I've attached some images to this email. Hopefully they give you an idea of the surface dirt.

The image with the black paint at the bottom, shows the colour of the original brick underneath - on the patch where I was a little overzealous with a wire brush.

So yes If you have an idea of the best approach for me I would be grateful. The result doesn't have to be perfect - but it seems a shame to not try anything while I have the scaffold up.

with the steam cleaner - is this what you mean:

And is there a danger with some kind of pressure washer machine that I could damage the brick.

Thanks again.


Last seen: 5 days 17 hours ago
Joined: 08/23/2012 - 23:35
Carbon deposits need stronger chemicals to be removed.

Hi Michael,

Thanks for the pictures. These are carbon deposits and the Neolith 39N would likely do nothing. Here is what we would do:

1. Spray the area with Neolith 425 (use a spray bottle). Neolith 425 is a de-greaser and will soften the carbon deposits within a couple of hours. After two hours use the steam wash to wash off the chemical. At that stage do not try to clean the brickwork - just lightly wash off the chemical:
- Do not keep the nozzle too close to the wall to avoid blasting bits off the bricks and pointing.
- Do not spray on one place for too long in order not to saturate the wall with water too much. The wetter the wall gets, the stronger efflorescence post effect will be.

2. Once ready with Neolith 425, apply a coat of Neolith 625HD which is the actual cleaner. Use a tar brush or a brush with a curved handle to avoid any chemical streaking down your arms. ALWAYS USE RUBBER GLOVES, PROTECTIVE CLOTHING AND MASK/GOGGLES. Leave the chemical to work for around 20 minutes, then wash off with the steam wash. If needed, you can repeat this second step with Neolith 625HD.

3. Application with Neolith 625HD would most likely leave salt deposits on the brickwork which will result in the efflorescence effect (the chemicals reacts with the bedding mortar). You can minimize this by spraying the wall with vinegar (a 5L container is £3 at Macro). Let it work for a day and then wash off. If crystals still appear, repeat the vinegar application after a week.

In regards to the steam wash, the cheaper one would do a perfect job on your brickwork - you dont really need power for this, for you the aim is to wash with high temperature which any steam wash would do.

A side note: Looking at the pictures I've noticed the pointing - looks solid cement to me. If this is the case, then any moist in the wall would come out of the brick and not the pointing, increasing the brick erosion. If you want to extend the life of the bricks, the pointing should be a lime mortar, allowing moist to escape from it and not from the actual brick.

Hope that helps, but let me know if I can help with anything else.

All The Best,

Michael (not verified)
Brick Cleaning

Hi Clement.

Thanks a lot for that great rundown.

The 625HD sounds like quite assertive stuff. I guess I would need to put up plastic sheeting to make sure none escaped onto the street/neighbours etc, when i was applying and washing?

I've read about the downsides to cement pointing. If one were to tackle that as well would it done before of after the cleaning?

My house is a small is terrace. Image attached. 4.5 x 5ish meters with bay etc. Do you think I'm being realistic in tackling this job myself?

Anyway thanks again

Super helpful information.

Clement (not verified)
Always brick cleaning first, then re-pointing.

Hi Michael,

Sorry for the late response, a bit busy these days..

Dont worry too much about the washed off 625HD going on the street - despite being corrosive, it is bio-degradable so it will do no harm to the environment. Do protect your windows however as it will react with the glass.
It is a good idea to put some protection on the side of the scaffold and stop the spray going to your neighbours.

Always brick cleaning first, then re-pointing.

You sound very enthusiastic and thats all you need - your facade is small and you should be able to cut the old pointing in a couple of days. Use a small grinder with a diamond disk and cut along the centre of the pointing, then use a chisel to remove it from the brickwork. Be careful not to cut the actual brick with the grinder and gently with the chisel on the brickwork - ultimate aim is to preserve the bricks.

For the new pointing use NHL3.5 for the mortar and in terms of how to do it check on YouTube - I bet there would be tons of videos. If you're unsure about anything, shout and we'll help.

Good Luck,

Michael (not verified)
Brick Cleaning

No problem! Thank you again for the kind advice.

Cheers Clement!

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