Matching mortar

[Graham Jones]

Hello,

I need to do some re-pointing, the sand used in the existing mortar has tiny stones in it so I assume it is sharp sand. But would this be only sharp sand or could it be a mixture of sharp and soft?

Is there anything wrong in just using sharp sand (and obviously cement) for re-pointing? Will it be hard to work with?

The other problem I have is matching the mortar colour, B&Q and Wickes only seem to sell very dark orange building sand. This is totally the wrong colour for me. If I went to a builders merchants (Jewsons for example) would they have a choice of sand colour?

Also B&Q sell kiln dried sand which is a much paler colour, what is this for?

Thanks,

Graham

[dom]

What's the building material (stone/brick)? How old is it? Is it lime mortar?

On older buildings, the sand used may be just whatever could be sourced nearby - with just organic matter removed - no grading.

[george [dicegeorge]]

lime or portland cememnt?

My pointing volunteer mixed grey and white cement, and went to Rathbones in Hereford where they had over 20 different sand colours to choose from.

Still not perfect - where another used too white a mix on the chimneys I went up aterwards with mortar paint mixed to a greyer colour!

[g]

[mark]

When you do your experiments with mortar mix , wet the existing mortar then do your comparisons.

mark

[stuart noble]

Often only looks paler because it's dry.

[Dave Liquorice]

Brushing into block paving? It may look paler because it is dry.

[Phil L]

Trying to match mortar like this is almost impossible - even if you had the exact same mix that was used originally, it wouldn't match because the original is aged and weathered. All you can do is try to get as close a match as possible. Buy a few different sands and mixes and give it your best shot but don't worry too much if it doesn't match

[Graham Jones]

Thanks, interestingly the colour of my daughter's play sand from Tesco would be a good match. But what are the differences between building sand and play sand?

Graham

[Jim]

Play sand would be no good for mortar. The particles are far finer and it doesn't have any of the grit in it - great for not getting stuck under fingernails but not good for mortar. It's also washed a lot more so doesn't stain your clothes yellow as building sand would.

You can get dyes for mortars, try a builder's merchant. You need to make some up and leave it to dry and weather to accurately match a colour - this is not a quick process! I think you should expect the mortar to lighten up over a period of at about 6 months to a year.

[stuart noble]

AFAIK building sand particles are also very fine, we're just not used to seeing it dry. The yellow pigment can be rinsed out easily enough because it stays in solution long after the sand has sunk to the bottom. Not sure how much influence it has on the overall colour though

[NT]

For pale sand just look around at what's on offer. Dried is fine in pointing, but sounds like you need sharp. I'd just drive to a few BMs.

NT

[The Natural Philosopher]

yes. even yellow sharp sand (Iron oxide IIRC) is both washable to an extent, and also when used with white cement a very whiter shade of pale..

sea sand is often grey..and somehat more ruunded off.

Our sand here comes from glacial terminal moraines and alluvial deposits thereof. Its further to remove the gravel, which is sold separately, and its fairly yellow. I can get different stuff..there are some coastal quarries, but it costs more. Its furher away.