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Posted: Wed Apr 18, 2012 10:11 pm
by MK1Chris
Apologies if this has been covered before, but as a first-time flag-layer, I wonder if somebody could give me a spot of advice on how to mix a reasonable colour-match mortar for grouting between sandstone flags?
I guess I am after something light, like a Cotswold Stone sort of colour.
Do I just need to get some yellow soft sand and mix in around a 5 or 6 to 1 ratio with regular cement?
I've been building some retaining walls (which I will face with Cotswold stone eventually) and have been using around a 4 to 1 ratio with regular builders sand and the mortar for that has dried very grey in colour.
I assume the sand colour is the key here?
I know you can get dyes, but I want to avoid this if possible as it sounds too tricky to mix up different batches and still get the same colour each time!
Posted: Wed Apr 18, 2012 10:14 pm
by GB_Groundworks
you need to use a coarser grit/palster/sharp sand for pointing than a bricklaying mix, do you want a match or contrast? snowcrete can be used to help with teh colour but as stated the sand has the biggest impact on colour, snowcrete also makes a much stronger mix as i recently learnt from our resident concrete expert
Posted: Mon May 14, 2012 9:45 am
by mnlad743
You'll be hard pressed to achieve the colour you mention without using a pigment in your mix. A yellow sand/white cement mix will give you a very 'soft' or pastel yellow colour but if you need something stronger in the way of colour then you have little choice but to use a cement pigment. They are not really all that difficult to use, you just need to be consistent in your ratios. Most pigments are used at ratios somewhere between 4-6% in relation to the amount of powdered cement in your mix (they can be used up to 10% concentration but that borders on the max and can result in your mix being a little soft, best to stay 'south' of 8%).
I recently pointed a patio and used a Dark Brown pigment to get a contrasting colour. I used a 500ml jug to measure out my materials (I used a 3-1/2:1 mix). Using a digital kitchen scale I weighed up a 'jug' of white cement and then calculated the amount of pigment based on a 5% concentration, every batch of pointing mortar was made-up using the jug for measuring out the sand and cement and I weighed up the pigment dose.
It would be pretty simple to scale this up for a larger scale project, simply substitute a builders bucket for the jug. The key will be to keep the ratios the same and weigh up the pigment dose in relation to the weight of the cement in that first bucket. Where most people go wrong with pigments is if they use the 'typical' builders-labourer form of measurement. That is - to throw shovels full of materials somewhere in the general direction of the mouth of the mixer, some goes in, some doesn't. To make matters worse, the shovel has half as much on it at 3pm as it did at the start of the day. If you attempt to use pigments and mix in a hap-hazard method - you'll get hap-hazard results. Mix consistently and you'll get consistent results.
Posted: Mon May 14, 2012 6:57 pm
by lutonlagerlout
easipoint buff is what you need
LLL