How to get a smooth even surface?

[Grumps]

I need to lay a 3-4mm smoothing underlayment on top of a screed floor prior to fixing vinyl tiles (Karndean). Any tips to ensure a smooth even surface? I thought either;

1) Just mix it up and pour it on; it's really easy; just do it! or 2) Use an 8mm notched adhesive spreader thing. This would ensure that the underlayment is applied to the correct thickness, then I could smooth over any ridges that didn't self-level.

It's going to be about 100kg of mix, and it'll be mixed in several loads. Is there anything I should be aware of when applying a new load to the edge of the existing stuff?

Thanks all.

[Chris Bacon]

Personally, I'd pay someone to do this job, who has done it for a while before. The technique seems to be to mix the stuff up and lay it on bloody fast, using a float to distribute it quickly to an approximatly even thickness, stopping after a few seconds, well before the stuff's taken any sort of set.

[Ian_m]

I watched some men flatten levelling compound on a huge concrete area at work prior to vinyl flooring. They mixed from what looked like a continous supply mixer, but more interestingly spread it out using like a broom with nails for the brush bit and had boots with spikes on to they could walk around on the area under work. Also put tape covering on walls, as they splashed a bit and cloths of floor areas to protect them, unlike the clown the did our conservatory floor who mixed on our patio leaving splashed blobs on both patio and wall that were a b*gger to get off.