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Whitish lines appearing
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Thick and Thin coat EWI render systems.
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TOPIC: Whitish lines appearing
#3
Whitish lines appearing 10 Years, 5 Months ago Karma: 0
Hoping somebody will have an answer. I have a bit of experience with machine applied monocouche render, but this was the first time using thin coat system.

I LACed it and meshed it on day one, rubbed it up and then applied Weber plast TF on the second day. It wasn't a massive area so I think that me and 2 other guys should manage. Its okay, but I would like to get flatter next time. We rubbed it up as advised but is not so flat as I think it should be. The other thing is no it's drying you can see whiter lines at the scaffolding baords. What is this? How do you make it flat and all even colour?

Much apprecited
Richard
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#5
Re:Whitish lines appearing 10 Years, 5 Months ago Karma: 7
Hi Richard,

I'm not sure why you were applying TF without having training first. But anyway.

So this was over the top of cement board I pressume? Okay, so reading here it sounds like you applied the full 6mm of LAC and mesh on the same day? That I wouldn't have done. To get this backing coat of LAC thoroughly flat, apply the first coat of LAC, then apply the mesh - bedding it in with a thin coat over the top. You should be leaving about 3mm depth for the following day. 3mm on day one, 3mm on day 2. Roughly.

So on day 2, blast on the rest of the LAC full depth, and rule off flat, flush with all your beads.

Allow it to 'pick up', the LAC should be firm to touch with a soft crust. Sponge it well in circular motions (if LAC moves beneath the crust, leave it to firm up more). Time here is going to depend on the weather and direct sunlight on the wall.

With a long, very flat spatular (not some well used bent bannana shaped thing), 'flatten' in your spatted walls. (This will be almost identical in nature and principle to MP75 at this stage.) Your LAC is now wet and perfectly 'FLAT'. Now leave it alone. Don't try to get out 'surplus fat lines', just leave the whole thing alone.

The LAC needs to pick up again. You'll know when it's ready because you touch it you won't leave a finger print in it. Using a soft sponge, texture it all over. This will rub out any surpless fat lines and give you a perfectly flat and uniform fine textured LAC finish. Ready for your TF topcoat the following day. Now, if it's an over-cast day, no sunlight at all, I'd be spraying on the LAC in order to get it on a whole lot quicker, since LAC hangs around for centuries without sunlight on it.

The above IS the way to finish LAC perfectly flat and even for a thin coat render. You could just forget half of what I said above, and just sponge it once. The result will be a wall nowhere near as flat!

Now for your topcoat (of weberplast TF)

Prime your LAC. It won't take long to dry.

The topcoat is applied very thinly and evenly. The 'whiter lines' you say you are getting between lifts sounds like you are rubbing up your (supposedly 'wet edge') too late. Organize yourself and your gang a little bit better so that you can maintain your wet edges consistently and think about what you're doing. If you're all arse about face, it's just gonna go wrong. So, you start to apply your first lift. I don't know the size of your wall, but after about 5 minutes, one of you will drop below and start to apply (and rub up if necessary) just below where you started and work along the second lift paying full attention to maintaining workable edges, and (really) keeping it alive for the rest to drop down shortly and start filling in. And you'll be leaving the edges intentionally thicker so that they hang for longer. When you drop down, you'll 'cut through' these with your float and rub out evenly into the render above - which you must ensure doesn't pick up before you've rubbed up the fresher coat below into it. If it does, you'll risk 'gluey tearing' and whiter ghosting.

That's how it's done. Good organization and you won't go wrong. If you're still not sure, let me know and I'll come out on site with you.
Scott
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Gender: Male Utiform Plastering Machines Location: All over the place!  But West Sussex mostly
Last Edit: 2009/06/01 01:03 By werB7Dev.
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Keep machine plastering!

Scott
Utiform UK
 
#10
Re:Whitish lines appearing 10 Years, 5 Months ago Karma: 0
This is right we do it like this. We are good teem in rendering doing the weber. If you need help on job we come and do it for you.
Greg
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