White Residue on Bricks after Repointing (Picture)

[Reginalddean]

Hi

I have just repointed an area of my house, all seems to have gone well , except! The bricks around where I have repointed have a very thin layer of white residue that I cant clean off!

Heres a picture

http://picasaweb.google.com/DeanHain/WhiteResidue/photo#5181337192838009970

I did get alot of mortar on the bricks as I went along but I was cleaning the bricks with a wet towel after every couple of feet.

Does anyone know what caused this and how I can clean the bricks?

Thanks

 

[Shytalkz]

That'll be mortar staining then...you made it worse by rubbing it with a towel, as you've pushed it into the brick pores.

Try this:
Hydrochloric acid is only used to remove mortar stains from clay brickwork. Generally, hydrochloric acid should not be used to treat any other stains or at any other time during the life of your brickwork. If used incorrectly, it can cause unsightly staining that is more difficult to remove. It is very important that protective clothing be worn and that the safety and chemical storage precautions necessary for working with hydrochloric acid are followed. The following procedure is recommended when cleaning with hydrochloric acid:

All mortar droppings should be removed using either a metal or wooden scraper.
Protect all areas which may come in contact with the cleaning agent as recommended by the manufacturer of the proprietary cleaner. Special care should be taken with window frames, aluminium dampcourses and gutters.
Saturate the area of brickwork to be cleaned and all adjacent areas below with water.
Use the correct ratio of hydrochloric acid and water:


Light coloured bricks - 1 part hydrochloric acid to 20 parts water
Dark coloured bricks - 1 part hydrochloric acid to 10 parts water
Under no circumstances should more than 1 part hydrochloric acid to 10 parts water be used. It is better to scrub more vigorously than to use more acid.


When cleaning, try not to work in direct sunlight.
Always begin at the highest point and work down the wall.
Only clean small areas at a time, for example one square metre, so as to allow adequate time to wash off the cleaning solution, to ensure no staining occurs.
Allow solution to remain on wall for 3-6 minutes before scrubbing. Be sure not to scrub the joints.
Rinse thoroughly, making sure all cleaning solution has been removed.

Note: light coloured bricks should be rinsed with a neutralising solution, such as bicarbonate of soda or washing soda, instead of water.

I did get alot of mortar on the bricks as I went along

No kidding...!

By the way, if you've used a strong cement/sand mortar there (which it looks like), it will trap moisture behind it and eventually the brick faces will spall through freeze/thaw action.

Woody and/or Noseall might have some more comments to make in this regard.

 

[Reginalddean]

Thanks for the swift response,

Luckily I have only repointed the lower three courses as I intend to paint with either masonary paint or bitumen so will avoid the acid cleaning, sounds dangerous

The mortar along the top looks like a strong cement mix but that is the original mortar (not guilty!!), a neighbour told me it contains some local stone??

I used a 3:1 sand/cement mix, is this too strong?

Im starting to panic now, hope the wife doesnt read this!!!

 

[Shytalkz]

The original mortar along the cabling line and two courses below looks like a cement/lime/sand mortar to me, is the house from the 50s? If so, it won't be an especially strong mortar. I see someone's had a go at it before, half way along.

Using 1:3 you'll probably be ok, especially if you hide it up from 'er indoors

 

[Reginalddean]

Thanks Shytalkz,

I have now re-evaluated and decided to paint the lower 4 courses to hide all the mortar staining!

I do need to repoint lots of areas above the lower courses but luckily didnt do today that as I was hoping to find a way to dye the mortar to match the existing grey colour.

A numpty question if I can, what is the idea when repointing? Should I try and get the new mortar in without getting any at all on the brick? If some goes on the brick what is the best way to get it off before it stains?

I was very slap dash with this lot, basically smearing it on! Lesson learnt though,

could I use masking tape? Now I am showing my novice status!!

Cheers

 

[Shytalkz]

Rake out the joints to a depth of approximately twice the width of the joint, clean out with a wire brush. Dampen down the brickwork (not wringing wet!). Mix some mortar (above the dpc, use cement/sand/mortar in 1:2:9 ratio), not too wet but just so it's nice and plastic (sticks to a trowel when you tip it on its side, doesn't slide off), put it either on a small board or trowel, use a small pointing trowel and carefully work the mortar into the joint, finishing flush with the face of the brick. Form a weatherstruck joint by holding the pointing trowel at an angle and running it along the pointing, so that the top of the joint is slightly recessed. Alternatively, use a bucket handle, or a small length of hosepipe to form the joint. Doing it like this should not result in you getting much on the wall at all; any that does, knock it off with the trowel straight away, don't go rubbing it in (as you've found out ).