What mortar is this please??

[Dougie212]

Hi there,

Having repaired my underground drainage, I’m looking to repoint the wall. It’s been suggested to me by a builder quoting that the mortar is cement based but my terrace house was built in 1890 so I expected it to be lime. Ive taken a few pics, and I appreciate it’s difficult to tell by pictures alone, but is anyone able to confirm if my mortar is lime or cement please? The pics are all the same wall so I’m hoping it’s all the same type of mortar.
Also, as an add on,in a previous post, I asked about cleaning the bricks off or painting.. If it’s lime mortar I’d rather try and clean the paint off the bricks than paint as I’m guessing breathable paint is costly. Again, I know it’s probably even more difficult to tell what paint it is on a picture but can anyone suggest a method of cleaning the bricks please. We are looking to move soon so it’s simply for appearance to sell so hope not to fork out on a sand blasting type firm.
Thanks in advance as always !!
Dougie

 

[John D v2.0]

Looks like it may have been over pointed with cement.
If you can see white flecks in it then it's lime. If you scrape some out and put vinegar on then lime will fizz or have bubbles.

 

[Dougie212]

Thanks John.. I’ll give the vinegar a go. Is there any point in me repointing it with lime now??

 

[stuart45]

If the original was lime mortar, if you hack out all the cement mortar then repoint with lime.

 

[Dougie212]

Ok Stuart. Thanks. Am I right I’m thinking from the year the property was built and the type of bricks then the mortar should be lime?

 

[stuart45]

The chances are that the original will be lime mortar. Although OPC was around at that time, it wasn't until the 20's and 30's that it started getting popular to gauge into the mortar.

 

[Dougie212]

Brilliant, thankyou, and do you think that although the house has stood for years having been pointed in cement it would be better to re do it in lime?? Particularly the lower parts?

 

[John D v2.0]

Ours was lime with a thin layer of cement over, and very soft bricks then cracked paint. The bricks were spalling in various places.
Most of the lime in the perps had dissolved and washed out.
I scraped everything out what was loose and used nhl3.5 mortar to replace it. Then painted with supposedly breathable masonry paintp sinceaint. then it's been fine.
The main thing is the mortar would be softer than the bricks. And the wall should be able to dry out quicker than it gets wet.

 

[Dougie212]

Lime mortar it is then... is the techniques much different than cement? Just out of interest, what breathable paint did you use John? It’d save me a whole heap of of work trying to clean them off...

 

[John D v2.0]

I didn't use much cement before that, but i just watched a few videos. Give it a good mix with sharp sand in a bucket, use a narrow towelt to shove it in the joints, flatten it off and then hit it with a churn brush to open the surface. The idea is to keep the surface open rather than leaving a tooled finish.

 

[stuart45]

Ideally NHL needs to be mixed for 20 mins in the mixer, left for 20 to fatten up, and then mixed again for a couple more mins.

 

[Dougie212]

Brill.. thanks John! Am I right in thinking I’m best to avoid doing it in the cold?? That does put me in a bit of a dilemma because I do need to fit some bricks back round my new toilet pipe and waste pipes and so using lime may delay this..?? I don’t know...

 

[stuart45]

I've got a lime job to start for someone in the next couple of weeks. For DIY it's not the ideal time of the year to start a job, but 5c and rising is OK for NHL3.5, and covered up well at night.
If it can be left for the spring it's better.

 

[Dougie212]

Brilliant, thanks Stuart. I might get the brick work back in and hold off the pointing until the spring then.. the pointing has failed all the way through the bricks due to the leak we had underground.. I’ve pulled the plaster off, so when I re point outside can I re do the inside to just as the outside with the lime?

 

[stuart45]

Yes, you can use it for the inside as well.