I'm renovating a house and have now chipped away the plaster from the old chimney (built in 1936). We want the bricks to be visible. The joints are pretty poor, so all of them need to be repointed. The bricks are 10cm deep (22x6x10).
How much should be scraped out to ensure good repointing?
Any other tips when I repoint?
Which mortar?
How do you avoid smearing mortar on the bricks around the joints?
What's the best way to clean any smears?
Should any primer be used inside the joints before mortaring?
How much should be scraped out to ensure good repointing?
Any other tips when I repoint?
Which mortar?
How do you avoid smearing mortar on the bricks around the joints?
What's the best way to clean any smears?
Should any primer be used inside the joints before mortaring?
Hey, I'm just a happy amateur, but I've done quite a bit of plastering and masonry work (including a brick wall with two arches 
). Masonry is fun! (how I can think that, I don't know...)
Since the joints are bad, I assume there's quite poor/porous/old mortar in the joints (from 1936)?
I would make sure to properly prime with (at least my favorite) Optiroc's primer. More a form of concrete glue, softener, and more, but I think it works much better than "regular" primer especially when working with mortar. I believe it's called "Vidhäftare", primer Swedishified I assume Available in a white 1L bottle. It can be a bit tricky here though; if you get primer on the stones, it might not look so nice (will leave shiny marks where you smear the primer) But if you could just get some in the joints, it would probably be good. Otherwise, aim to water generously the day before and then a couple of extra splashes on the day. It absorbs like crazy now that it's quite warm and the mortar sets too fast/becomes weak (or rather dries out too quickly, so it can't set properly). If you get primer there, you can take it easy with the watering though.
Considering the old mortar, I would probably apply C-mortar.
Wipe away as much mortar as you can while it's still not set properly. You should be able to scrape off mortar all day. It's easiest to wipe it away while it's wet, because you will make a mess
Make sure to fill the joints thoroughly; I would have tried to get about 3cm of mortar in there at least. The pointing trowel is crucial, though you might have already sorted that out. Mine has a nice curve on the handle for smoothing the joints. Otherwise, use what you have, a piece of conduit, dowel, or whatever to smooth the joints. Something wooden that can retain a bit of moisture might be preferable.
It can take time to fill the joints; if you have a lot to do, keep an eye on the start so it doesn't "set away from you" and get too hard to achieve a nice finish. If you decide to try and apply mortar in all the joints and then go back to smooth afterwards.
If you're uncertain, it's good to have a float on hand; it can save many situations when plastering walls. But here you'll probably need to make one yourself, a bit of thin foam or felt around something that has the right curve for the joint. With such a tool, it is at least possible to somewhat spruce up surfaces/joints that have set a bit too long.
). Masonry is fun! (how I can think that, I don't know...)Since the joints are bad, I assume there's quite poor/porous/old mortar in the joints (from 1936)?
I would make sure to properly prime with (at least my favorite) Optiroc's primer. More a form of concrete glue, softener, and more, but I think it works much better than "regular" primer especially when working with mortar. I believe it's called "Vidhäftare", primer Swedishified I assume
Available in a white 1L bottle. It can be a bit tricky here though; if you get primer on the stones, it might not look so nice (will leave shiny marks where you smear the primer) But if you could just get some in the joints, it would probably be good. Otherwise, aim to water generously the day before and then a couple of extra splashes on the day. It absorbs like crazy now that it's quite warm and the mortar sets too fast/becomes weak (or rather dries out too quickly, so it can't set properly). If you get primer there, you can take it easy with the watering though.Considering the old mortar, I would probably apply C-mortar.
Wipe away as much mortar as you can while it's still not set properly. You should be able to scrape off mortar all day. It's easiest to wipe it away while it's wet, because you will make a mess
Make sure to fill the joints thoroughly; I would have tried to get about 3cm of mortar in there at least. The pointing trowel is crucial, though you might have already sorted that out. Mine has a nice curve on the handle for smoothing the joints. Otherwise, use what you have, a piece of conduit, dowel, or whatever to smooth the joints. Something wooden that can retain a bit of moisture might be preferable.
It can take time to fill the joints; if you have a lot to do, keep an eye on the start so it doesn't "set away from you" and get too hard to achieve a nice finish. If you decide to try and apply mortar in all the joints and then go back to smooth afterwards.
If you're uncertain, it's good to have a float on hand; it can save many situations when plastering walls. But here you'll probably need to make one yourself, a bit of thin foam or felt around something that has the right curve for the joint. With such a tool, it is at least possible to somewhat spruce up surfaces/joints that have set a bit too long.
I have tried to get an answer to something in my own thread but without result, so I'll try here.
If you would rather try to repair the joints instead of redoing them, for example, filling drill holes, etc. Can you use something like husfix, or will it be such a different color that it's not worth it? We have an identical situation as TS.
If you would rather try to repair the joints instead of redoing them, for example, filling drill holes, etc. Can you use something like husfix, or will it be such a different color that it's not worth it? We have an identical situation as TS.
You need to scrape out at least 15mm from the joint, then grout with some fancy mortar (personally, I think regular plaster mortar B looks best). Mix the mortar for a long time to make it smooth, and apply it in the joints with a so-called grout trowel. The mortar should be mixed relatively dry to minimize splattering on the bricks. Work a bit at a time, and when the mortar is dry (usually only takes a few minutes on old masonry), go over all applied mortar with a grout stick. This is a wooden tool similar to a wide butter knife. After you have scraped off with the grout stick, brush the joints with a dry scrub brush and voila! Super neat joints.para said:
PS these are not expensive tools, will cost you around a hundred at the hardware store.