[CtEkM8Vq]

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?

[Ndptbudd]

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?

Yes, it is efflorescence.
It is coming from soluble salts being transported by water that is coming into the wall, usually from below.
In your case, it is probably calcium carbonate - try a bit in some vinegar and see if it fizzes. If it is calcium carbonate, then it is probably coming from concrete or mortar. It will be being transported as calcium hydroxide and then be carbonated when it reaches the surface.

The green stuff will be biological. It may respond to a very mild solution of copper sulfate.

[Assentesy]

Nice work, morrie. Nailed it pretty well, speaking as a fellow far less experienced chemist in a life long ago.

[AAAESLLESO]

Bit of rising damp happening there, Kingy, wonderful thing, destroying houses all over the world.

[CtEkM8Vq]

While I respect your chem knowledge, morrie, I am fairly sure that the green is a chem reaction.

[AAAESLLESO]

http://en.wikipedia.org/wiki/Damp_(structural)

[Ndptbudd]

While I respect your chem knowledge, morrie, I am fairly sure that the green is a chem reaction.

Hmmm. Thinking cap on. Not too many options there. Iron and copper are the first things that spring to mind. Perhaps elfram might have some ideas?

[CtEkM8Vq]

Bit of rising damp happening there, Kingy, wonderful thing, destroying houses all over the world.

Sometimes it is a good thing. A bloke I know tried to sell his(awesome) house because of it, and a friend of mine bought it really cheap. He fixed the damp problem and now lives in it.

That house was my number one lotto buy.

[Ndptbudd]

Here is a thought. Dab a small patch of the green with:

A: Hydrogen peroxide or Napisan, an oxidant.
B: Sodium metabisulfite brewing sterilizer, a reducing agent.

Both should kill any organism, but if it is chemical, we might expect some differentiation in colour.

[CtEkM8Vq]

try a bit in some vinegar and see if it fizzes. Just scraped some into a plate and added some vinegar. No reaction. Just a brown ooze.

One test is not much of a scientific experiment, so I will try again tomorrow.

[Ndptbudd]

Just scraped some into a plate and added some vinegar. No reaction. Just a brown ooze.

One test is not much of a scientific experiment, so I will try again tomorrow.

A brown ooze? Was it brown vinegar?

[CtEkM8Vq]

No, white vinegar.

It is a year old, but should still be ok.

[Ndptbudd]

No, white vinegar.

It is a year old, but should still be ok.

So the white vinegar with the white powder turned brown?

[CtEkM8Vq]

I have just tried again, and am currently uploading a vid of the results.

[RorieSorNearop]

h++p://www.marld.com.au/Info/Vanadium/Vanadium.htm

[CtEkM8Vq]

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.

Remedies

Method 1. Apply VanGo and leave on till the stain disappears, then wash off. This method does not require neutralising. If a white residue appears simply hose this off.

Method 2.Oxcid can be applied to the stained bricks without pre-wetting. This should be neutralised with Neutril. Do not wash off. This method cannot be used on vanadium stains which have darkened as a result of cleaning with hydrochloric acid.

Method 3 . Apply Noskum to the dry bricks. Wash off after the stain disappears and neutralising with Neutril.

Note: More water even that used during the cleaning process may induce more vanadium to the surface. If this occurs, the process may be repeated.

WARNING: These chemicals are S6 poisons and must be stored safely away from children. See warning and first aid information on individual bottle labels and on the CHEMICAL SAFETY page.

[Ndptbudd]

h++p://www.marld.com.au/Info/Vanadium/Vanadium.htm

Glance comes through with another excellent link!

[CtEkM8Vq]

http://s68.photobucket.com/albums/i1...2-21-10-29.mp4

[Ndptbudd]

http://s68.photobucket.com/albums/i1...2-21-10-29.mp4

Interesting, that yellow/brown colour, even with the white material. Clearly you have some carbonate, but it would seem that you have also got a soluble metal compound in there.

[Ndptbudd]

h++p://www.marld.com.au/Info/Vanadium/Vanadium.htm

Oxcid! Fortunately, we have an expert right here on the forum with respect to this chemical!

;-)