Blog

18/01/22 - brick@admin

1. All bricks must be laid clean

It is even more critical to lay concrete blocks as well as concrete & dry pressed bricks extremely clean. This is even more important for dark oxide mortars if you want them to stay black after cleaning.

• Do not leave sandy mortar on the bricks or blocks. When sandy mortar smears harden they become much more difficult to remove. This leads to damage during the brick clean. Mortar smear without sand usually cleans easily without damage. 
• After pointing, wait for the mortar to go off before cutting. This will prevent sandy smears from forming.
• After cutting use a FIRM brickies brush, to remove all soft dried sandy mortar on the bricks. It is extremely important to allow the mortar to go off and dry or be crisp and crumbly before removing. This helps prevent the smearing of green or uncured mortar on the brick face, arris and perps and will help prevent brick clean damage from occurring.
• On raked beds, brush or clean all the exposed edges. Make them sharp, visible & clean!
• Don’t leave chariot balls or splatter in raked beds. Remove all splatter on walls and on the brick face, arris and even more importantly around the perps, don’t patch up holes with the back of your trowel. This will leave sandy butterfly wing effects around the perps  Instead, butter up heaps so you don’t have to backfill holes. After jointing, don’t use the soft brushes that are commonly used, particularly in Melbourne. They won’t work on crisp mortar but will spread wet green sandy mortar around the arris and onto the brick. This sandy mortar will harden and it cannot be cleaned easily.  Strong acids (very strong) will be required to soften and dissolve it, and high pressures will be required making it even worse. It’s these practices that lead to most of the mortar damage commonly seen in Victoria.
• Sponging – If required use a clean damp sponge (not a wet sponge) after the mortar has gone off, been cut and brushed. Make sure you wring the sponge out with clean water each time. Bricks cleaned with dirty sponges or dirty water often become impossible to clean.
• Don’t sponge rough, heavily creviced or deeply pitted bricks. It will ingrain and permanently fix the mortar in the crevices making them difficult to clean and it can become almost impossible to clean if you use water treated with acid. Never sponge wet green uncured mortar onto the bricks as it is almost impossible to remove once it sets. Even smooth bricks have millions of micro crevices so be careful as it is extremely time consuming and expensive to clean if you smear green mortar on any brick

2. Use as 3700 M2 or M3 mortar (unless environmental conditions specify otherwise)

• Fatty sands may not need as much lime to remain workable so adjust as required. 
• Make sure the mix is consistent and calibrate with buckets. The standard practice of  using 18-24 shovels of sand to one bag of cement makes mortar too hard as the ratio is more like a 3:1:1 or 4:1:1. Brick cleaners find that shovelled mixes often vary from being too hard through to being too soft on the same house. The solution is bucket batch!

3. Don’t use plasticisers or lime replacement chemicals – just use lime!

• Lime is the traditional plasticiser of choice. It is a carbonate and readily cleanable with acids.
• All Brick Cleaners have problems with chemically treated mortars for many reasons – (see below).
• If plasticisers or lime replacements are used then lay the bricks extremely clean (see point 1 above) and clean them within 3-5 days.  We have often found that it’s practically and economically impossible to clean these mixes, without doing damage, even after a few days.

4. Remove all splatter and droppings from bed, bricks and slabs.

5. Cover top course in wet weather

• This prevents water from settling in the brick cavity and so will stop bricks from staining.

N.B. Plasticisers and lime replacements make mortar harder to clean as: ​

• Chemical plasticisers can make sticky and extremely hard mortar
  • Our field tests have proved even if you only use 1/4 of the recommended amount of some plasticisers, it will make bricks (and tools) uncleanable within a day or two.
• Most are surface active air entraining agents which coat the mortar to make it more workable and extend it’s life on a board, but they also make small bubbles which makes  mortar lighter as well as reduce the water content. This makes a much harder and more brittle mortar with micro-cavities which leads to many other problems for cleaners and later on for home owners after the acid clean. 
• They can also waterproof mortar and prevent acids from penetrating and working.
• Some also contract, tighten and harden mortar making it more water proof and impervious to acid.
• Some have a glue to make mortar stick tighter to the bricks. Acids cannot clean these mortars.
• Plasticised mortars can conflict with Lime and become far too hard to clean.
• Plasticisers when added to the premix water may even conflict with lime replacement products
  • This combination can make a sticky, unworkable and unusable mix in the mixer.
  • They can also make a soft friable mortar that will fail the hardness test.
• FINAL CAUTION: Lime replacement chemicals don’t have any lime so M3 (6:1:1  mortars) made with them will fail the mortar test. The same will happen if you use plasticisers to replace lime:
  • Plasticisers and Lime replacements are chemicals that replace lime. They do not have any CaO so they reduce the amount of calcium oxide (CaO ) in the mortar which is a measure of limestone  or (CaCO3). This will lead to mortar test failures when Builders do a mortar test. If it fails they may back charge the brick layer for the repointing or re-bricking costs. ​Therefore only use them if there is no alternative!!!​

N.B. Test Plasticisers and lime replacements agents rigorously before selecting, as the consequences, if they prevent bricks from being cleaned, can be devastating and extremely expensive to repair. We can help with this process if required.