Dislike working with plaster and mortar, find it tricky to get it right, though I have managed to fix a few square meters where plaster has come off the basement wall and repaired/cast the threshold to the garage, but now I'm trying to get the firebricks up in the fireplace.
I bought a bag of refractory mortar, but initially tried to use regular plaster mortar C, to practice a bit in the not-so-hot areas.
I pre-soak, slurry, and the mortar adheres to the stone and the wall, but splits in the middle. Have I mixed it poorly, or is it too little water, or am I just bad at this?
When I watch videos online, the mortar looks delightfully gooey and almost clay-like, while mine looks more like gravel slush.
After a day's drying, I can take down the stones by hand and crumble the mortar.
Soon it will be fix or adhesive instead and a four-hour VHS with a fireplace.
I bought a bag of refractory mortar, but initially tried to use regular plaster mortar C, to practice a bit in the not-so-hot areas.
I pre-soak, slurry, and the mortar adheres to the stone and the wall, but splits in the middle. Have I mixed it poorly, or is it too little water, or am I just bad at this?
When I watch videos online, the mortar looks delightfully gooey and almost clay-like, while mine looks more like gravel slush.
After a day's drying, I can take down the stones by hand and crumble the mortar.
Soon it will be fix or adhesive instead and a four-hour VHS with a fireplace.
Member
· Västernorrland
· 12 037 posts
or maybe watering a bit too generously.
I don't think I have too much water, the structure is dry in the middle between the stone and the wall, like damp sand and it separates.
It's like there's a lack of binder.
It's like there's a lack of binder.
Are we talking about bricklaying or plastering?
I think you might have too little patience; it takes several days before the mortar gains a decent strength. I'm not very knowledgeable myself either. However, I believe I've understood that you should use a lot of water. If you lift a trowel of mortar out of the bucket, it shouldn't have any "stiffness," it should almost run off the trowel. But IF it actually runs off the trowel, then you have too much water. For plastering, it should be a bit looser, so that it partially actually runs off the trowel.
As I said, no expert advice, I might be wrong.
Another thing with C mortar is that it mustn't get too old. Ordinary lime mortar can be re-wet if it starts to harden in the bucket, but any mortar with cement in it is perishable. The cement sets and cannot be reactivated like lime.
I think you might have too little patience; it takes several days before the mortar gains a decent strength. I'm not very knowledgeable myself either. However, I believe I've understood that you should use a lot of water. If you lift a trowel of mortar out of the bucket, it shouldn't have any "stiffness," it should almost run off the trowel. But IF it actually runs off the trowel, then you have too much water. For plastering, it should be a bit looser, so that it partially actually runs off the trowel.
As I said, no expert advice, I might be wrong.
Another thing with C mortar is that it mustn't get too old. Ordinary lime mortar can be re-wet if it starts to harden in the bucket, but any mortar with cement in it is perishable. The cement sets and cannot be reactivated like lime.
Thank you for the response. I will try with the refractory mortar.
C should be suitable for chimney construction, but on the other hand, the stones are stacked on each other, whereas in the fireplace, they "hang" on the wall.
C should be suitable for chimney construction, but on the other hand, the stones are stacked on each other, whereas in the fireplace, they "hang" on the wall.