Roughcast Patch Repairs - Colour Matching

[greyam100]

Hi folks

Grateful if a roughcaster could help me out here.

See photo's of job here where you will see the colour required:
//www.diynot.com/diy/media/albums/roof-drain.22488/

Old vent has been removed from external wall & filled in with concrete as far as possible - upper part was packed with mortar to seal the gap/hole. Now need to finish it off with a roughcast coat (1 or 2 render/mortar coats??)

I now need to try and match the colour of the existing roughcast. I have the stones which are Canterbury Spar.

Can anyone advise the materials and mix ratio I need to match the colour? Lime required to affect colour? White sand or normal colour builders sand? Any tips on how to apply the stones on such small area, 1 by 1??

I'm aware it wont be exact math but as near as possible.

Thanks

 

[stevethespreader]

I think we have a roughcaster on this forum somewhere

 

[greyam100]

Thanks for that. Is he hiding?!! Maybe on holiday, the cheeky rascal.

I can't see a way to direct my questions directly in that direction............

 

[stevethespreader]

His username is roughcaster im sure he will be along shortly although its not roughcast you have its pebble dash or drydash i myself would be tempted to use a 6/1/1 mix not sure if i would keep the round shape though

 

[roy c]

What I would do would be to knock off the dash coat around the hole back to the scratch coat probably 3 or 4 inches all round it, Then bring the hole out with a 5-1 sharp sand and cement and a drop of W/proofer mix, level with the scratch coat. After that I would put some expanding metal over the old hole that you have filled in and let it over lap the scratch coat that you have exposed and make sure it is below the finished dash surface. When it has dried out you can put some sbr or pva on the area and coat it with your 5-1 mix and then throw your dash on to it ,and if necessary tap it down gently to bed it in. You will never match dash back in perfectly, so it's up to you to see how it looks and if you are happy with it. It is hard enough for a plasterer to do this so it looks passable so if you are going to have a go ,good luck. I wouldn't put any lime in the mix as it would probably make the render a bit lighter, it looks like no lime was used in the original mix. Tho I might be wrong about that..

 

[roughcaster]

I'd go along with what Roy says, plus, it's impossible to match the colour, and to make an invisible repair in any textured surface, ( roughcast, artex, tyrolean etc), unless you re-do the whole area. You can get a patch to look ok, and if you're happy with it, that's all that matters.
Like Roy, I don't think there's any lime in lime in your mix either.

 

[greyam100]

Thanks for the replies guy's

I hear what you are saying re colours not matching but one further fundamental question:

White cement or normal grey cement to affect clolour?

Thanks again