The Brew Cabin

Hello Tony. Congrats on your excellent site which (in its original McC family site form) is probably the oldest bookmark in my favorites folder dating back my u.r.g days.

I've just finished laying a patio using Stonemarket Trustone Torvale paving. I'm feeling quite chuffed because there were no major problems and its looking quite good. The problem is going to be the mortar colour for the pointing. My wife wants the sandy colour mortar as shown on the Torvale slabs on page 46 of the current Stonemarket catalogue. I think I would have to use far too much sand in the mix to achieve this. The 4:1 mix I used to lay the paving dries light grey.

Oddly enough, the mortar used on the brickwork of our house is the sany colour we want. I suspect the colour of the sand plays a big part. I'm using building sand for my mortar. The bottom line is that I need to achieve a sandy coloured mortar or as a second choice, a dark grey/black mortar for pointing. The wife is keen to avoid light grey. Any suggestions?

Cheers,

Paul.



(Edited by Paul Giverin at 9:35 am on July 4, 2004)

Hi,

I had exactly the same issues when I laid my indian sandstone patio. In the end I decided to use the buff coloured Geofix - very easy and provided a really nice sandy colour that complemented the stone perfectly.

If you are going down the mortar front, I can by experience (and mistakes) say this:

1) Most coarse sand from DIY merchants, etc produces a grey finish in a 4:1 or 3:1 ratio. (sand / cement)

2) I needed to go with a light mortar and used fine builders sand which produces a much beige / brown colour. (I am no expert, so whether it is correct to use builders sand is another matter, but I kept the ratio small to ensure strength).

Hope this helps (I'm sure Tony will provide more professional advice - I'm just working off what I have achieved personally)

Carl

The colour of a mortar is largely determined by the colour of the sand. Up here in t'north-west of Eng-er-land, the building sand is predominantly red (from the Bunter Sandstone which is an Old Red of the Devonian period) and so we usually get a pinky sort of mortar when it's mixed without using any dyes. For a lighter mortar, we use a silver sand, usually one dredged from the Mersey (lots of Pennine buffs and golds) or from Southport beach, which is buffy silver, or possibly silvery-buff.

In London, the building sand is much more orangey, and this is refelected in the mortar.

If you want a light-coloured mortar, then you need to start with a light sand. That image in the Stonemarket catalogue is ackshirley a light pink, whereas what your beloved wants is probably a honey-colour, or possibly ash-blonde (Wimmin have funny eyes when it comes to colours - they see colours that have poncey names, while all us blokes see is light and dark).

The GeoFix would certainly give you that honey-buff colour, at a price, or you might be able to buy a bag or two of a pre-mixed, lime-based mortar of a specific colour. Only certain BMs supply these mortars, but there's no harm in asking.

However, if you want to mix your own, get hold of the lightest-coloured sand you can find. Oddly enough, this sometimes turns out to be the block paving jointing sand which is a definite silver sand in some parts of the country. Mix this, with a buff dye, at 4:1 to make a suitable pointing mortar.

You'll have to do a bit of trial and error to find the exact amount of dye to produce the shade required. It may be that you need to use a yoghurt pot full of dye to each bag of sand, or you might only need a tablespoonful.

The best way to do this is to mix up a half-bag of sand (20kg), with 5kg of cement, in a wheelbarrow. Add one tablespoon or 50g of dye, stir in to disperse the colour and then remove a trowelful to make a "pattie" on a piece of polythene or old carrier bag.

Add another tablespoon/50g of dye to the remaining mix, stir it in and make another pattie, and so on and so forth until you've 5 or 6 patties all a-drying somewhere safe from the kids.

Give them at least a day, preferably 3-5 days, to cure and harden, and then get your beloved to judge which shade she prefers. The 'patties' should be hard by then, so you can safely place them against the flagstones to judge that the colour co-ordination is as required. Let your missus decide this - you just nod in agreement: it's a lot easier, and much less painful, in the long run. :)

Thanks Tony and Fandang for your helpful replies. I'll try and get some silver sand and experiment. Am I right in thinking that you have to use a wet mix when using dyes? I was hoping to keep it dry to avoid any staining.

Cheers,

Paul.

It doesn't have to be wringing wet, but it does need some moisture to ensure the dye is dispersed fully. You can manage with a very, very, very stiff mix, as shown on the Pointing Case Study page, but it must contain some water, or it just won't perform.

Just as a follow-up, I couldn't source any pre coloured mortar so I bought some yellow powdered dye. I mixed up some samples to get the best colour and mixed at a ratio of 1 part dye to 33 part cement. I mixed the dye and cement thoroughly before mixing with building sand at 4:1.

I tried a small area of the patio with a wet mix but this was going to be painfully slow. Even worse was that the dark Trustone Torvale stone was prone to staining.

I then decied to try a dry mix. I did read your case study and I appreciate the need for moisture to release the dye but with a little experimentation I cracked it. Using a plastic syringe I squirted some water in the 10mm joints making sure no water got on the surface. I brushed in the mix very carefully and using some suitable dowelling I pressed the mixture into the joints until firm and neat. I then set the garden hose to a fine mist and sprayed the patio which wet the mortar but didn't splash the mortar onto the stone.

The colour in the dye was released and I ended up with the colour I wanted. The patio looks great so "job done".

Thanks again for your help Tony.