36" Pompeii in DC

[Laurentius]

Re: 36" Pompeii in DC

What about having a spray water bottle on hand and spray your bricks, rather than adjusting your mortar?

[rsandler]

Re: 36" Pompeii in DC

Spray bottle! That's the ticket. I'll give that a shot tomorrow. FWIW, I wasn't so much thinking of adjusting the mortar to deal with absorption, but wondering if the absorption problem indicated the mortar is too dry.

[Laku]

Re: 36" Pompeii in DC

More pictures from today's work attached. The first two show an abject lesson in why you shouldn't mortar bricks together when you can't see all sides of the joint (even if it's pitch black on the other side because you're working at night).

I used a head lamp for laying bricks in dark.

[deejayoh]

Re: 36" Pompeii in DC

The spray bottle will definitely help - but it looks to me like you need to mix your mortar a little bit wetter (should be like stiff pancake batter) and use more. Mortar should squirt out the edges a bit when you place your brick. Cut that bit off with your trowel (think masons call it the squirts or snots or something like that), and use it to butter the edge of the next brick you're going to lay.

[rsandler]

Re: 36" Pompeii in DC

Finished the first dome course today, and started on the second. Also removed the supports from underneath the hearth. Hearth did not fall down. All told, quite successful .

I used a head lamp for laying bricks in dark.

There you go; I thought I was pretty clever having rigged up a lamp clipped onto the deck railing to shine down on the oven. Joke was on me!

The spray bottle will definitely help - but it looks to me like you need to mix your mortar a little bit wetter (should be like stiff pancake batter) and use more. Mortar should squirt out the edges a bit when you place your brick. Cut that bit off with your trowel (think masons call it the squirts or snots or something like that), and use it to butter the edge of the next brick you're going to lay.

Got it. A couple of my mortar batches have been as wet as you're saying, but not most of them. In general I haven't been able to get much squishing, and so instead of buttering the bricks (which leads to the joints not being as tight as I want them, since the mortar won't squish out of the way), I've been setting the brick in position with the IT and cramming mortar in with the trowel. Ends up wasting a lot of mortar that falls off around the sides. I'll keep in mind that it should be squirtable; maybe I'll have more luck buttering then.

On the other hand, I've been getting nice tight joints on the inside of the oven, with essentially no clean-up of mortar on the inside required. In principle as long as the bricks are tapered, there's enough mortar to hold the angle, and the joints are tight on the oven side, the bricks can't actually go anywhere, right? I'm thinking of Les's oven here. My joints aren't as tight as his, but I'm also putting mortar in the vertical joints as much as I can.

That said, stuffing mortar into the joints is slooow. Figuring out how to butter successfully would speed things up enormously!

-Ryan

[rsandler]

Re: 36" Pompeii in DC

I should probably explain the series of arch pictures in my post yesterday, lest anyone get the wrong idea.

Friday night I built about 2/3 of the arch, with 6 bricks on each side. Saturday morning I finished the arch with another 6 bricks. Saturday afternoon I climbed up in the oven to try to modify my Indispensible Tool (an exercise which did not work, as it turns out). I stand up from messing with the tool, and of all things the back of the waistband of my jeans catches on the inner lip of the arch, and the 6 bricks I'd put in that morning go flying. Much groaning, cursing and futzing later, I had the arch repaired and better than before, with something resembling a proper keystone this time.

Wouldn't want anyone to think the re-do stemmed from some kind perfectionism or skill, rather than me being a total clutz

[UtahBeehiver]

Re: 36" Pompeii in DC

I think we all have done redos whether on purpose or not. Nice job on angle cuts, joints are looking tight.

[texman]

Re: 36" Pompeii in DC

RSandler

Make small mortar batches and keep working the batch as you are working. If you are using homebrew, you can retemper (add water) some, but not too much to keep the batch workable. The correct mortar is the key. I dipped my bricks as well as i was laying to keep things moist as you go. You definitely want the "squish" when setting the brick instead of packing mortar. Keep trying it will get easier. Had to laugh at the belt loop trick. Looks good, nice job.
Tracy

[rsandler]

Re: 36" Pompeii in DC

Thanks all, this is all really helpful. Sounds like I just plain need to Use More Water. On the bricks, through the spray bottle, in the mortar...

I have been trying to keep my mortar batches small though--I knew that in general, but it was driven home when for my second or third batch I decided I'd try to make it twice as large as the first one or two, and ended up throwing half of it away :P. One thing I did on Sunday to help with this is I mixed up a jumbo batch of dry mortar in a big plastic tub with a lid (as opposed to scooping the ingredients for each batch). The tub then sits in the wood storage area under the oven. This means I can make a mortar batch as large or small as I want, and eliminate having to schlep back to the garage after each batch. Not exactly a big innovation, but it sure made yesterday's work more pleasant!

-Ryan

[Tscarborough]

Re: 36" Pompeii in DC

Make sure you are using oven dried sand if you premix it, as there will be enough moisture in bulk sand to cause a set.

[cobblerdave]

Re: 36" Pompeii in DC

Gudday
Try using a metal paint stirrer on your electric drill to mix small amounts it makes mixing a batch easy
Regards dave

[rsandler]

Re: 36" Pompeii in DC

I've been working on the oven a little bit each evening, and I finished course 2 just now. I'm still having a heck of a time with buttering; even with spraying the previous course like crazy, soaking the brick being laid, and having the mortar downright runny, the stuff is still too dry to squish mere seconds after being spread. Frustrating! I'm getting a little better--figured out that part of the trick is spreading just slightly more mortar than is needed (reducing the amount of required squishing), using the previous brick as a guide. Also tonight I tried wetting the previous course be draping a soaking wet towel on it. This worked okay, and will likely work better when there's more room for it.

Pictures attached. Combination of mortar problems, IT problems, and the addition of bevel cuts on this course made things a bit sloppier. I think it will hold though :-).

BTW, how long does the homebrew take to set fully? I'm wondering when it's safe to take the arch form out.

-Ryan

[texman]

Re: 36" Pompeii in DC

That looks really good. Nice start and setup. Tight joints and a nice arch.
What trowel are you using to butter with? I used this 7"brick trowel and a margin trowel to mix with. The 7" makes it much easier.
Tracy

[deejayoh]

Re: 36" Pompeii in DC

homebrew will set overnight enough to hold that arch

looking good. just follow that IT!

[rsandler]

Re: 36" Pompeii in DC

Tracy, DJ, thanks! I've been using a 7" "pointing trowel", which looks a lot like Tracy's picture. The trowel is great; it's the mortar that gives me grief . I'll get the hang of it sooner or later. Probably just as I'm closing up the dome.

Took out the arch form this evening. It stands! After I put the little one to be tonight, time to start cutting bricks for course 3.
Cheers,
-Ryan