ajax i have been told to use a anhydrate primer and benferflex c2 on a screed what do you think

Originally Posted by wayne

ajax i have been told to use a anhydrate primer and benferflex c2 on a screed what do you think

I am assuming it is an anhydrite screed ..... sorry

Firstly there is no such thing as an "anhydrite primer". There are only primers for use on anhydrite and these can be acrylic, epoxy or polyurethane. Some people have used SBR but with mixed success. Neoprene is not really suitable in my opinion. Acrylic presents the most risk and I have seen many failures on these types of primers but some are better than others. BAL and Ultra do some good ones.

My guess is that who ever you are talking to are trying to sell you a standard acrylic primer for use on anhydrite. BEWARE IMO.

If you are looking to use Benfer I would think you would be better with Befergyps as it is specifically forulated for these screeds.

Benferflex is cement based so the issue is basically one of non compatibility. Cement and anhydrite do not stick together. If you use an acrylic primer you still have this risk if there is any moisture present and especially on underfloor heating. If everything is perfect there should not be a problem. When you find the perfect building site let me know.

If you want to use a cement based adhesive I would suggest you think about a much more robust system like a water dispersed epoxy primer such as Laybond Screedmaster epoxy, tremco CS epoxy or Isoseal from Flowcrete. All of these have been specifically developed for use on anhydrite screeds. They are generally not much more pricey than acrylics and are much more effective against the migration of sulphates.

Alternatively a gypsum based addy might be of use.

It was posted in an anhydrite screed thread Alan before i moved it..

Oh OK Dave. Did I give an answer on that one or not.......think I going a bit senile today.

It was screedmaster epoxy thread, so i gave this one it's own..

Yeeeey! my very own thread.....

Now is tat a good thing or a bad one.........

Deffo a good one Alan, respect

alan with the benfergyp do they still recommend removing laitence off screed and priming ?

ted

why not use Benfergyps

where can i get it from? im based in leeds.

Originally Posted by wayne

where can i get it from? im based in leeds.

there is an outfit in South Yorkshire (Might even be leeds) who can supply it as they are a benfer stockist. I can't remember who they are but will back track my diary and find out for you.

Originally Posted by tedley34

alan with the benfergyp do they still recommend removing laitence off screed and priming ?

ted

They say it can be used without a primer. I am not sure about that personally but will leave them to offer what guarantees they need to offer. My concern would be suction into the screed drying the addy too quick so I would always primer personally.

As for sanding off laitance. It depends if there is any on the screed or not.

It may need to be sanded for other reasons than laitance however as I have yet to see the screed which is clean and free from construction debris.

the primer i was told to use was called mega anhydrate primer. benfer have apparently tested it and it works

Originally Posted by wayne

the primer i was told to use was called mega anhydrate primer. benfer have apparently tested it and it works

never heard of it but then there are a lot of primers I have never heard of. I will check it out though and let you know what I think.

the fact they spelled it wrong does not bode well of course.

do benfer do an acrylic or epoxy primer? looked on the website couldnt see. Any ideas on prices for benfergyp?

ted

Benfer certainly do an acrylic benferprim I think and I beleive they do a polyurethane primer. trouble is with Benfer that htey have no offices in the UK so everything is done through distributors. I usually phone the TTA if I want stocists for certain manufacturer cos most of them are members.

The last price I got for Benfergyps was about 6 months ago and it was £13.50 plus VAT per 20kg bag. Price will vary cos the distributors will be buying in Euros so the exchange rate will affect the price.

Originally Posted by wayne

where can i get it from? im based in leeds.

Direct tile importers or monks cross bathrooms and tiles (same people, based in york)

Direct tile importers that was the one. I had a name as well but can't find the page in my diary where I wrote it down.

You are posh Alan, I have bits of cardboard, with tel no's on no diary for me

when I say Diary Phil.....i mean the back of old receipts stuck together with gaffa tape.......occasionally old bank statements.....drive my mrs mad cos I pick up any old bit of paper and make me notes on it.......