[CtEkM8Vq]

Where would I purchase some Oxcid without bringing down the CIA upon my head?

[Ndptbudd]

Where would I purchase some Oxcid without bringing down the CIA upon my head?

D**gers timber cleaner. Neutraliser is calcium hydroxide, aka slaked lime.

Or, instead of that system, you could use dilute sodium hydroxide.

[Patgaepx]

Would Oxcid be oxalic acid?
I used this once to clean iron stains from my bricks.
It wasn't too difficult to get, I think I bought it as a powder from the brick company.

Edit just checked the MSDS and it is oxalic acid

[Ndptbudd]

It seems likely that the colorant in the white powder is traces of Vanadium. The white colour would most likely be due to calcium carbonate. You can also get sulfate efflorescence that could be white as well.

Anyway, you could treat the green with a spray of dilute sodium hydroxide. This, I am assuming will form sodium vanadate. Then it is washed away. It will be a bit messy and of course sodium hydroxide is very corrosive on the skin and eyes, so gloves and goggles would be essential IMHO.

However, if the white stain does contain calcium carbonate, the caustic soda isn't going to remove it. So the oxalic acid treatment might be more useful. It will have more chance of taking out any calcium carbonate along with the vanadium, though calcium oxalate is pretty insoluble. The suggested neutraliser for the oxalic acid treatment is dilute calcium hydroxide. That might tend to leave a bit of a trace of white unfortunately.

[AAAESLLESO]

West or south facing wall is it, Kingy?

[gettoblaster]

I have been having some problems with efflorescence since my house was built in winter 2 years ago. It appears as a green "mould" on the surface. In the last couple of months I have noticed a white powder appearing on the bottom course inside the garage.





Is the white stuff also efflorescence?

Where is it coming from?

What is the best way of removing it?

What is the best way of removing the green efflorescence?

Is part of your garage underground ?

[JacomoR]

From the Vanadium link:

Description

Vanadium salts are naturally present in most clays used to produce white, cream and other light coloured bricks. These bricks usually give a warning by showing a yellow-green stain on their surface after they have become wet and been allowed to dry out.

Vanadium stains are not powdery crystalline deposits and cannot simply be brushed off. They are often mistaken for moss or algae which usually grows in damp areas across the whole face of the bricks and mortar joint. By contrast, vanadium stains appear on dry walls, normally as patches on the brick only.

Causes

Vanadium stains are the result of water- soluble vanadium salts. These salts are put into solution by excess water migrating through the bricks (particularly cored bricks) and brought to the surface as they dry out. During this drying-out process the water evaporates leaving the vanadium salts (and any other water soluble salts) on the brick surface. This process can occur whenever the bricks are subjected to excessive water from rain either before or (more often) during the bricklaying process. If the stains are not removed prior to cleaning with hydrochloric acid, they may turn a darker colour and be more difficult to remove.

I'm no chemist and reckon this is as good a possibility as everything else mentioned, but I'm curious about one thing. The vanadium link says "Vanadium salts are naturally present in most clays used to produce white, cream and other light coloured bricks". The blocks Kingy has posted a pic of are concrete Besser blocks, does the same apply to them as well?

[CtEkM8Vq]

West or south facing wall is it, Kingy? It is North facing.

Is part of your garage underground ? No, but it is possible that there is some dirt up against the bottom course on the outside.

The blocks Kingy has posted a pic of are concrete Besser blocks, does the same apply to them as well? No, they are a pale cream face brick.


Morrie, thanks for your replies. I will try out a few things when I get a chance this weekend.

[Ndptbudd]

No worries kingy. Good luck with it. Small trials would be best I think.

[gettoblaster]

No, but it is possible that there is some dirt up against the bottom course on the outside.



No, they are a pale cream face brick.


.

If I would be you , I would remove the dirt on the outside , then I would look if there is a down spout from the roof . There must be a moisture collection in the other side of the wall, and so as the water forces its way by pressure against your brick and on the inside of your garage you have a relative low pressure . So water of different color from outside paints your brick

[Assentesy]

Haven't been lurking in the last week - bizzy bizzy bizzy! But I can't offer much more than has been said. I presume the oxalic chelates the vanadium. The inorganic chem part of my brain has been filled up with jazz music, fungi and so on. But I love reading this kind of thread, because it reinvigorates my fuzzy old cerebrum.

[CtEkM8Vq]

I have been doing some experiments today, and learned a few things.

[Assentesy]

Nice piece of video - thanks for that inyteresting interlude. But do you really want the orange colour?

[CtEkM8Vq]

Nice piece of video - thanks for that inyteresting interlude. But do you really want the orange colour?

At the end of the video you can see that the orange colour came away easily with the Hydrochloric acid and left almost no staining at all. When I get some spare time, I will be giving a larger area a dose of it.

[Sertvfdnhgjk]

Was the choice of safety glasses influenced by the chance of the efflorescence starting to fluoresce really, really brightly?

[CtEkM8Vq]

Was the choice of safety glasses influenced by the chance of the efflorescence starting to fluoresce really, really brightly?

It was influenced by the fact that some of those chemicals are nasty to the face, and the welding helmet was the only full face covering I have.

I had no desire to be on one of those Fail videos

[Ndptbudd]

Very interesting kingy. I am surprised about the lack of effect with the caustic soda, as that was the chemical in the commercial removal product.

[freddyujnf]

I have been doing some experiments today, and learned a few things.

now every post of yours i read i'll hear that voice.

[CtEkM8Vq]

now every post of yours i read i'll hear that voice.

In my own mind I sound much like Kamahl, I'll thank you to hear it that way too

[Ndptbudd]

In my own mind I sound much like Kamahl, I'll thank you to hear it that way too

Why are people so unkind?