Lime ?

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currymunster

currymunster

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Been getting annoyed on a rendering job!!
I don't think I'm the best renderer and still have a lot to learn I expect but I've done enough of it only not with lime!
Customer wanted lime in mix so I thought no problem. Only I've been having trouble with the scratch coat drying so quick it's not sticking and cracking. (Scratch - 3 Plasterers - 1 Builders - 1 Lime and 1 Cement)
When 2nd coating (4 Plasterers - 1 Builders - 1 Lime and 1 cement ) Before I can get one Belle mixers worth on the wall it's past rubbing up which means that I'm rubbing up an spreading at the same time - Really hard work!!
Now I thought it was the sika rendermix but decided to put less lime in. Put a quarter of the amount of lime in and the scratch seems to hang around a lot longer!!
Does this sound right? Am I doing something wrong with the mix? Should lime only be used in winter????
Silly questions I know but I feel like a chemical plasterer trying to learn old fashioned (Decent) ways.

Cheers Guys

James:RpS_thumbsup:
 
I would not have it in the scratch, why the brickyard sand, why not scratch five render to one cement ,add fibres ,no lime,wet the wall before you start, leave second coat awaiting for a week, keep walls damp in the mean time, mix six sand one cement one lime with handful of fibres in the mix.ps waterproofer in the scratch,,
 
Only have the lime in the 2nd coat as john said , scratch waterproofed no suction for 2nd which there would of been in your scratch plus the lime equels quick dryin , Johns got it right though just thought I'd have my say :-) haha
 
I use a cement called BLI Limebond when I want to use a lime and cement mix. It has 20% lime content and plastisizer added.

I once used it on a scratch coat with Feb Proof and got stupid suction so never did that again! A plastering sand and cement scratch with water proofer added. For the second coat 6 sand 1 cement and 1 lime. I find if you reduce the sand less than 6 then reduce the lime accordingly. Too much lime and it cracks and as for using lime without a plastisizer then forget it too much water, dead as do-do and shrinkage cracks.
 
Thanks guys.
Don't know why I put lime in both coats - Suppose I just assumed you did as I remember the bloke I learnt with doing it.
Got water proofer in both coats. Builders Sand? Well years ago I used some TP sand and it was awful - the water seemed to run down the wall through the sand once applied which meant the top rubbed up quick and the bottom hung wet for HOURS. Spoke to a few people and the general consensus was add 1 part builders as its not washed and the dirt and fat in the sand will help to retain the water longer. But no more as it can cause shrinkage cracks because of the fat and dirt. Worked a treat and always stuck to it. Using Jewson now and I believe it's Charing sand so maybe time to drop the soft stuff eh ?

James
 
Rigsby said:
I use a cement called BLI Limebond when I want to use a lime and cement mix. It has 20% lime content and plastisizer added.

I once used it on a scratch coat with Feb Proof and got stupid suction so never did that again! A plastering sand and cement scratch with water proofer added. For the second coat 6 sand 1 cement and 1 lime. I find if you reduce the sand less than 6 then reduce the lime accordingly. Too much lime and it cracks and as for using lime without a plastisizer then forget it too much water, dead as do-do and shrinkage cracks.
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Right, so one part lime is with a 6 to 1 mix else its to much lime. Have to ask - is 6 in one not to weak? I've always been scared or less than five to 1. I usually do 4 to 1 scratch and 5 to 1 2nd coat.

James
 
currymunster said:
Right, so one part lime is with a 6 to 1 mix else its to much lime. Have to ask - is 6 in one not to weak? I've always been scared or less than five to 1. I usually do 4 to 1 scratch and 5 to 1 2nd coat.

James
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Five to one is fine as is six and one/one ,remember before cement there was no cement so ...
 
How much waterproofer did you put in each mix for the scratch and is it a 3 in 1 (waterproofer/plasticiser/retarder) ?
 
DannyMac said:
How much waterproofer did you put in each mix for the scratch and is it a 3 in 1 (waterproofer/plasticiser/retarder) ?
Click to expand...

Well, I usually use Cementone Freeflo but no one had in my town so I ended up with Sika rendermix. Now I used the concentrated one shot stuff a while back and it was okay but this stuff is the 5 litre type which from memory as the tub is on site two towns away is a plasticiser / waterproofer and salt inhibiter. don't believe is said it was a retarder. but as said was caught and usually use Freeflo. amount to use said 250ml to 500ml per bag of cement. I reckon I'm using about half a bag to a mix so picked the least amout and halved it to 125 ml which works out half a red bull can (stanley cut it in half - Jolly nice chap is stanley )
 
Hi guys, Never I say never put waterproof in the scratch coat, it will blow the top coat. 1st coat 6 sand 1 cement 1 cup of feb leave to dry for 2 days. 2nd coat 5 sand 1 lime 1 cement and a small amount of feb, half of what you put in the first coat and 1 cup of waterproof. Before you apply the 2nd coat spray down the wall. Then when rubbing up, always have ur hose, fine spray to help rubbing up with, gets a perfect job. Hope that helps.............

Spoon
 
Spoon said:
Hi guys, Never I say never put waterproof in the scratch coat, it will blow the top coat. 1st coat 6 sand 1 cement 1 cup of feb leave to dry for 2 days. 2nd coat 5 sand 1 lime 1 cement and a small amount of feb, half of what you put in the first coat and 1 cup of waterproof. Before you apply the 2nd coat spray down the wall. Then when rubbing up, always have ur hose, fine spray to help rubbing up with, gets a perfect job. Hope that helps.............

Spoon
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That's not right.
 
Well it was late when I posted last night. That mix is for a double mix ie, 10 sand 2 lime 2 cement 1 cup of waterproof.......
Am I a stirrer? wtf does that mean
I guess the last 25years I've been doing it work, hahahahah
 
Hmm seems like I can't edit my post, was meant to say guess I've been doing it wrong for the last 25 years............haha

Please explain why I am a stirrer John?
 
Yeah I guess my scratch is a tad on the weak side, but I've never had any work go wrong on me. The point I was trying to make was about the waterproof in the scratch coat, I've seen guys put it in the scratch coat and it's gone hollow and cracked on them, that's why I always put it in my top coat.
And before you guys start, yes I know that waterproof can go in either coat. I just prefer mine in the top coat. On that note I'm out here, wheres the bar? :RpS_biggrin:

Spoon
 
The waterproofer goes in the scratch coat to control and give even suction over the walls entire area.

whether or not you put it in the top coat is up to you.
 
Never seen a top coat blown because waterproofer was in the scratch, possibly because the scratch had not cured before the second was spooned on,,,,
 
I remember Mr spoon on Steve Wright in the afternoon on radio 1 back in the 80's. Was that you spoon?
 
I'd rather use feb in the scratch then use waterproofer in the top coat. I think waterproofer weakens the scratch and hasn't the same suction which helps the bond IMO.
 
I've done render with no waterproofer or lime, a good scratch coat spread one day and the floating the next, the scratch is still holding moisture which gives you time to float out.
 
Just to put my 2p worth in here for ya currymunster.
I have a 45gal drum, put 5ltr of waterproofer in and fill with water. That's my gauge for that. I never use plasticiser.
Scratch coat over ordinary block is 4sand 1cement.
If scratch over stone I tend to do 5sand 1 cement 1lime.
Top coat 6sand 1 cement 1 lime.
Never had a wall fail on me yet. It works for me;)
 
Always put the additives directly into the mixer - that way you know it's where it should be and not left in the bottom of a water bucket :RpS_thumbup:
 
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