Picture framing - Must be a better way

[Thefox]

always seam to come across this issue, usually just a small bit in a corner somewhere but still a noticeable imperfection . the marks seam to be made worse when i seal the paving not sure what keeps causing it. my first thought is the cement through the stone. i always wet the stones before laying more to clean the cutting residue of the back. is sealing them before laying an option? and how would this effect over all adhesion of the stone to the mortar bed?. any thoughts?

5 to 1 mix and always a full bed!

[seanandruby]

read this

[Tony McC]

The paving needs to be wetted before jointing, to saturate the stone to the point where it is no longer sufficiently thirsty to draw in moisture from the jointing mortar.

Obviously, the paving can't be wet when the pointing is being done, so the stone has to be wetted the night before and the stone given a chance to become surface dry, but the interior of the stone will still be chock-full of moisture and in no mood to draw in anything more than a drop or two from the fresh mortar being crammed into the empty joints.

Pre-sealing may work, but it can also bring other problems, particularly of getting the mortar to bond effectively to the stone. Consequently, care has to be taken in the choice and application of an appropriate sealant.

Meanwhile, the good quality two-part resin mortars insist on the paving being abso-bloody-lutely saturated with water prior to applying the slurry and, when done properly, this does seem to eliminate practically all picture framing problems.

[Thefox]

Thanks for taking the time guys, much appreciated. i prefer to keep things simple, bond bridge seams like a lot of time consuming faffing project i am on at the moment is 65m2. however would be great for steps and similar vulnerable areas.

I reckon i see it more when laying the thinner 19m2 packs stones compared to the 15m2 thicker stones. makes sense that these would hold the moisture longer and be less likely to draw moisture when laid. i find a 22mm cal stone is more consistant in thickness then a 19mm cal stone.

thanks
Rich

[Tony McC]

What you think of as "faffing", some of us think of as "best practice".

[lutonlagerlout]

I have always had good results adding 150ml of SBR to my admittedly quite wet mix and pre wetting all flags before laying

I reckon the dry mix (traditional ) layers have more issues with adhesion

cheers LLL