Dissolving old lime mortar?

[Kinclad]

Hi there,

Its been a number of years since I posted on the forum, great to see its still vibrant.

I'm in process of having my clay/oak pegged tile re-roofed.

The ridge tiles have a fleur de lis and clover insert in them. Many of them had broken off so I had some new clay inserts made up by Tony Mugridge. (http://ajmugridge.co.uk/about.html).

So now I need to remove the old broken off inserts from the ridge tile, I'm presuming they have been bedded in lime.

Its important I don't break the ridge tiles removing the inserts so does anyone know of a chemical that will loosen up the lime mortar?

Many thanks in advance for any help.

Cheers,

Mark.

 

[Feltwell]

Well, any acid should affect lime - I'd start with brick acid and experiment! Often called brick cleaner, any builders merchants will have it.

I presume the inserts sit in a groove in the top of the old ridge tile?

If that doesn't work and the old insert remains are well stuck in, it may be worth carefully cutting a slot in the remains of the old insert with a diamond disc in a small 4 1/2" angle grinder - you can cut very precisely with these with care. A slot cut in the centre would then give you a space to gently tap the remains either side into. Or, if it went well enough, you might want to just cut them out with the disc and have done with - done carefully this will put next to no strain on the ridge tile, and if you did mark it slightly no one will see on top of your roof anyway, especially with new inserts mortared in.

Good luck!

Many of them had broken off so I had some new clay inserts made up by Tony Mugridge. (http://ajmugridge.co.uk/about.html).

I've just realised - I've seen this chap at work at the Blists Hill museum in Ironbridge, just down the road from me. Very knowledgeable he was to, lovely items he was making. I didn't realise he was independent of the museum.

 

[Kinclad]

Hi,

Thanks for your feedback.

Yes they have a groove.

I Have a photo but is there a problem uploading that? I get a message - 'Sorry, the board attachment quota has been reached.'

Cheers,

Mark.

 

[Feltwell]

Yes, it's a pain when it does that.

If you use a service such as Photobucket, which is free, you can upload your pictures there and then paste the

 

[Kinclad]

My very poorly roof

 

[charlieboy]

I Have a photo but is there a problem uploading that? I get a message - 'Sorry, the board attachment quota has been reached.'

Mark.

When this happened to me MatthewC posted "Go to "User Control Panel" and "Manage Attachments" and delete some old ones." which worked!

Can I also say that Tony Mugridge is a very knowledgeable and fascinating person with his explanation of how my house has evolved over the last 6 or 700 years or so! He spent a long time going over the house and was able to date part of the hearth to 1494 and the stone and timber framed part to earlier than that. He also made me some replacements for my unusual octagonal quarry tiles. It turned out that he lives less that a mile from me.

 

[Flyfisher]

Well, any acid should affect lime - I'd start with brick acid and experiment! Often called brick cleaner, any builders merchants will have it.

I agree in principle but wonder if it would be strong enough? After all, builders splash it all over brickworks to clean off mortar stains and presumably it doesn't damage the mortar joints?

I'm pretty sure brick acid is weak hydrochloride acid, around 5%. I buy 'spirits of salts' from our local hardware store, which is 32% hydrochloride acid and costs less than £2 for 500ml.

Easy to dilute down to 'brick acid' strength if that works, but also possible to try a much stronger solution. I know for a fact that it reacts vigorously with lime mortar when used neat!

 

[Feltwell]

A fair point FF, I agree, on reflection maybe normal brick acid will be a bit weak. Whatever is used needs using with care!

 

[plasticpigeon]

I bet most of the old mortar could be picked out with something, it usually gets pretty friable when it is old and exposed. Or it could be carefully cut with a hacksaw blade with the end cut off perhaps. Acid would work too of course, but i have found it discolours the surface of bricks and quarry tiles, they seem to go a bit pinker, and it takes a while for th old colour to come back. Does the surface of brick oxidise or undgo some other chemical change when left to the elements?