Maintaining an Old Blacksmiths 300+ years old

[AMc]

The reason the lime mortar is damp is because the cement based mortar in front of it is preventing the moisture from moving out to the surface and evaporating off. The moisture will be coming from the ground beneath the wall and from inside the house as much if not more from outside.

Adding cement to lime mortar messes up the chemistry of both causing it to be weaker than lime on its own - it really isn't worth going to all the trouble of repointing and ending up with a soggy wall and pointing that fails.

 

[MdB]

Two shovels full of builders sand ( NOT the washed type that is used for rendering), one shovel full of sharp sand and one shovel full of hydrated lime.

I would increase the lime in that (http://www.buildingconservation.com/articles/mythmix/mythmix.htm)
With three buckets of sand and one and a half buckets of hydrate in the mixer, I would expect to get three buckets of mortar out as the lime fills the gaps in the sand. If you use less lime, you still get three buckets out suggesting that the gaps between the sand grains haven't been fully filled.

Since I started this research I must admit it has been a nightmare.

There are so many answers to what should be a straight forward task.

90% of builders you will ask will put cement in the mix. Everybody here will tell you this is wrong as it traps the moisture - many of us have direct experience of removing the cement and their houses drying out. Modern materials / techniques for modern houses, traditional materials / techniques for traditional houses.

This doesn't mean that we all agree on what the best traditional techniques are as you can see in the above. Don't believe either of us, do your own research and come to your own conclusion which for lime mortar used for pointing is that the exact mix doesn't matter much.

 

[middi]

Two shovels full of builders sand ( NOT the washed type that is used for rendering), one shovel full of sharp sand and one shovel full of hydrated lime.

Middi

I have read that sand for lime mortar should be sharp and well graded but as you seem to have had success with the above mix, I might be tempted to give it go. Do you just mix and use it as you need it or do you have some sitting around maturing?

John

Mix and use the mortar as you need it, ie:- fresh.

 

[wozzy]

Thanks, oh and another important thing to ask would be what colour sand to use?

 

[MdB]

I have read that sand for lime mortar should be sharp and well graded but as you seem to have had success with the above mix, I might be tempted to give it go. Do you just mix and use it as you need it or do you have some sitting around maturing?

John

Mix and use the mortar as you need it, ie:- fresh.

I buy and open a new bag of hydrate when I need it. Any remaining hydrate gets turned into putty (by just adding water) or mortar for future use so that there isn't any chance of the hydrate going off in the bag. I've not noticed any difference in fresh mortar compared to matured mortar though the experts here claim that there is a difference and it is better to use matured.

(Don't try and mature NHL - it will set - but you knew that anyway)

 

[MdB]

Thanks, oh and another important thing to ask would be what colour sand to use?

Whatever matches and/or you like the colour of.

 

[johnandrew]

Wozzy

As far as sand colour goes I would go to the nearest builders merchant to get whatever they have and see if it produces a suitable colour lime mortar. If not then consider looking further afield.

Here are the (mostly sharp) sands I have bought from around our region (but not all extracted in the region)
Going clockwise from top left, we have

1.) Waddington Fell grit sand (Womersleys)
2.) Sherborn fine sand (Womersleys)
3.) Unknown origin (Mytholmroyd Builders Merchants)
4.) Grange Farm river sand (Barratts in Sowerby Bridge)
5.) Nosterfield (Womersleys)
6.) Leighton Buzzard (Womersleys)

 

[Penners]

Thanks, oh and another important thing to ask would be what colour sand to use?

Whatever matches and/or you like the colour of.

As MdB says, your choice of sand will possibly be the most important influence on the colour of your finished pointing. While it's not worth getting too obsessed about this (the mortar colour will mellow anyway in time) it is worth doing a few small trial mixes with different sands to help you achieve a colour that harmonises with the existing lime mortar.

 

[middi]

When the house was originally built the sand would have come from the local area.
Nowdays it could come from anywhere, hence the difference in shades and texture.
As suggested, a bit of trial an error is required in trying to obtain a correct shade.
Most of sand used in the early 19th century ,and prior to this, was heavily contaminated with soil. At times a lot of subsoil was mixed with the sand and as the mixture was heavily limed the sub soils acted as a good binder for the coarse sand particles.
One of the reasons why from one village to the next, let alone across the country, there is a difference in texture,mixes and aggregates or amount of lime used to build walls etc..
Most of the time it was the builders choise and whatever was easily available. The more important buildings were constructed using a more " constant" mix but the materials were still obtained as close as possible to the area in order to keep down costs.

Middi

 

[middi]

.....One other important point to remember is to leave the pointing to dry out completely before you judge the " colour" of the texture.

With newly pointed or constructed walls it will take min. three ot four weeks to fully dry and for the " white" mortar to be most prominent.
All lime mortar joints will " discolour" and assume a grey look when wet or not fully dried.

( you can observe this immediately after rain has fallen and again after a couple of days sunny weather, especially in old mortar walls)

Middi

 

[wozzy]

I would just like to say a big thankyou to you all for your time, comments and passing on your experiences. It has certainly helped to put my mind at rest, especially on the pointing front. No doubt I will be back at some time with other issues unrelated to the current subject.

I now have a lot of work to do and will keep you posted with my progress. I am curently almost ready to re-point the area to the right of the kitchen door, but before that I am replacing some damaged bricks.

I will over time add some photos.

Once again thanks everyone

Mick

 

[Penners]

I will over time add some photos.

Good - the more the merrier!

 

[wozzy]

Hi everybody me again!

I have now started pointing the house and started on the newest part of the house the extention, which unfortunately when built was not in keeping with the period of the house, in fact anything and everything they did to this house before I made the purchase was/is a mess. You would be shocked and annoyed but we bought the house because of the area and that it is on the banks of a river and besides some of these are cosmetic but time consuming. Anyway less of the boring stuff!

Anyway, the first bit of pointing as mentioned was done in the mix that the extension was built in. This is OK and as good if not better than the original and I used one of those applicators which made life a lot easier.

I have started to point the part next to our main entrance in a mix of builders sand,sharp sand, hydrate lime. 2,1,1 and this looks OK except that it is more time consuming than the last bit of pointing. I have found that you have to work with the mix quite a lot but that isn't a problem! What I have found is a problem is that I tend to get the mix on the outside of the bricks and no matter how I try to clean the surface it dries white. Any ideas on what to use to remove this from the bricks?

Has anyone used one of those applicators for repointing using lime?

I think that the mix would need to be sloppy in-order for the mix to go through the applicator and maybe this is not a good thing!

Maybe I should stick to working the mix like plastercine, cutting in strips and sliding into place using a trowel and board!

Thanks

Mick

 

[MdB]

I have started to point the part next to our main entrance in a mix of builders sand,sharp sand, hydrate lime. 2,1,1 and this looks OK except that it is more time consuming than the last bit of pointing. I have found that you have to work with the mix quite a lot but that isn't a problem! What I have found is a problem is that I tend to get the mix on the outside of the bricks and no matter how I try to clean the surface it dries white. Any ideas on what to use to remove this from the bricks?

Anything acidic. Try vinegar, any type of limescale remover or brick acid though this really is overkill. Put on and then leave. It is a chemical reaction so scrubbing won't help a great deal.

I of course haven't actually tried any of these so let us know how you get on.

 

[skier-hughes]

let it dry and use a brass wire brush if the brick is quite solid.

 

[middi]

Wozzy, it takes a bit of practice to be efficient at pointing in order not to " smudge" the brick faces.
It is not advisable to point bricks with sloppy mortar, it is a sure way to smudge the surfaces, especially if not too experienced.

Practice with a " stiffish" mortar flexible enough to force it into the joints by using a pointing trowel, any smudges can then be just brushed off or rubbed off within 15 or 20 minutes. This may leave a white residue stain but will wash off with rain, or it can be carefully be cleaned very quickly within a few hours with a soft brush and water.

The same cannot be said if sloppy mortar is used, the " smudging" tends to be more persistent and more time consuming to remove.

Ideally no cleaning should be required once you have mastered the practice.

Keep practicing :wink:

Middi

 

[robgil]

I am doing bits of my fire place at the moment , I clean any smudges off with a stiff toothbrush and a garden mister/sprayer. I first let the mortar go off a bit though.

 

[wozzy]

Hi Folks,

Well after a bit of hard work, I managed to repoint both sides of the main entrance. The problem I had was the colour and after deciding on what I thought was a colour that would blend in, once completed I decided that I didn't like the colour and therefore chiselled the lot back out and went with a colour which I am sort of happy with.

I did try using a firm mix but due to the amount I had to do decided it was too slow, and besides I have a lot more to do so I needed a quicker method. I bought a pointing applicator from B&Q and persevered, but found that to get it right was not easy and therefore got quite a bit of the mortor on the bricks. This I need to clean off and will get around to doing. To remove the stains I bought a product from Jewsons but need to wear protective clothing, masks, glasses etc so I have put off for the moment.

Whilst communicating through this forum I have watched several videos on YouTube and this guy who did look experienced in using lime mortar used an applicator just like the guns you use to apply sealants. No mess and looked much quicker than the applicator I used. I have since bought one once again from B&Q and I think this will do the job without needing to be an expert. The cost was £25. Can't wait to get going on the rest and once I have cleaned up the brick work I will post some photos.

Till later