Laying down mortar

[Unofornaio]

Re: Laying down mortar

Id say defiantly stick with what you have been using. If you switch you may have different expansion issues and after all I assume many ovens have been built here with great results using that recipe.Your ok just play with the water content of the bricks and the mud. You should be able to get it so when you set the brick hold it for a short count and it should stay.

Putting a nice layer of sand on the hearth floor will catch any mortar..and what ever else falls..Im sure everyone here has had them fall at one time or another. Heck I did a firebox rebuild about a year ago and had some fall at first. I don't think I have built a fireplace in years, nobody wants them and you simply cannot beat the price of a prefab metal one..Im gonna build one here at the house because I just like the look of them and I cannot justify being a mason and not having a fireplace..I think its in the code of ethics somewhere..

[Hendo]

Re: Laying down mortar

A huge part of laying fire brick is to get the moisture in the mud and the brick just right. Although for the new oven I will use a true refractory mortar ...

I can?t agree more! I?m using a pre-mixed refractory mortar, so all I can play with is the moisture content of the bricks. And it certainly makes a huge difference, not only to the rate of setup, but also to the plasticity, stickability and workability (all technical terms here!) of laying these things. And when you?re limited by a 2-3mm max thickness, if things aren?t spot on, the mortar is dry before you even place the brick!

So far, I?ve found the best method is to lightly spray the brick bed, using a small spray bottle, quickly dunk a DRY brick into a pail of water ? just in and out ? and thinly butter all four sides (two on the bed and two on the brick being placed). This gives me enough time to quickly rub or tap the brick into position before it sets up, which is usually within a minute or two. While it?s setting up, I have to clean up the inside face immediately, or risk having to scrape off dry mortar.

I?ve tried soaking the bricks, and they take days to go off thoroughly ? I knocked one out once accidentally, and although dry around the perimeter of the mortar joint, it was like plasticine in the middle, and this was two full days after laying it! So every time I cut another course of tapers with the wet saw, I leave the bricks for at least two days to dry out. Too wet bricks also seem to cause the mortar to go powdery in time, which frankly scares me. Hopefully it?s only the outside edge.

My brickie showed me how he does it, and he had a different approach. He didn?t wet the bricks at all, but placed the mortar as he would a conventional brick wall ? very thickly and just on the bed and the ?butt? face of the brick. Then he pounded hell out of it to reduce the mortar thickness to that required. Fine until some previously laid bricks started popping out due to the tapers! They have set up well though, and the mortar remained workable for far longer.

All very different from Dave?s mortar, which sounds much simpler for the novice. But it still comes back to experimenting to find that ?one best way?.

I hope to have mastered the process by the last ring of the dome!

Cheers, Paul.