First time 41" clay/homebrew oven.

[sandybits]

Re: First time 41" clay/homebrew oven.

You will lose about 20% of volume on mixing the vermiculite or perlite.

Cool. Well in that case I'll see how this, now, 80mm of insulation goes

[sandybits]

Re: First time 41" clay/homebrew oven.

Fore the price of a bag of cement just chuck it out and get a fresh bag.

Fair call. Save $10 on the bag of cement only to lose $50 worth of vermiculite/perlite.

[sandybits]

Re: First time 41" clay/homebrew oven.

A couple of pics from the first layer of 5:5:1:3 (vermiculiteerlite:cement:water) insulation. This went on about 25 to 30mm thick.

I used a brickies trowel to carry the mix to the dome, which was then tipped onto a plasters trowel, gently pushing it onto the dome. I felt it was quite easy to work with in this fashion.

I found the mixing (all dry ingredients mixed well then adding all the water) easy. I didn't go to hard in an attempt to try and maintain the integrity of the aggregate.

I will let this go off for a few days to a week before doing the next layer. It may be the last but I feel there may be one more after that.

[david s]

Re: First time 41" clay/homebrew oven.

Your mix will probably still work ok, but you should add 3 parts water, not 1.5.
If water pools in the bottom of your bucket, you've added too much.

[sandybits]

Re: First time 41" clay/homebrew oven.

Your mix will probably still work ok, but you should add 3 parts water, not 1.5.
If water pools in the bottom of your bucket, you've added too much.

Ahh, that was an editing problem. I was mixing 2.5 buckets each of vermiculite and perlite and 0.5 a bucket of cement with 1.5 buckets of water. When I wrote it up I didn't convert the water. Thanks for picking it up

[sandybits]

Re: First time 41" clay/homebrew oven.

I had a half hearted attempt at lighting a small fire yesterday. I think of myself who can usually get a fire going when needed, however I'm not having much success here.

As I said it was half hearted but still got most of the oven above ambient temps. Got other parts (under the flames) over 100 degrees C.

Will start another fire this afternoon and try for some higher temps this time.

Also figured that I will have to address my chimney sooner rather than later. I am already getting a little blackening under my patio roof (which I expected). I need to figure whether to go straight up and through (potential for leaks) or out and around (more cost due to the price of the flue). I'm sure there is also other issues with flue length and bends that I need to consider.

Cheers.

[cobblerdave]

Re: First time 41" clay/homebrew oven.

Gudday
Start of with a small amount charcoal BBQ heat beads increase the amount over time. Makes a good curing "fire" as there is not big flames shooting up to overheat your roof. Low and slow is the way to start off and the heat beads are easier to regulate than a normal fire
Regards dave

[david s]

Re: First time 41" clay/homebrew oven.

I had a half hearted attempt at lighting a small fire yesterday. I think of myself who can usually get a fire going when needed, however I'm not having much success here.

As I said it was half hearted but still got most of the oven above ambient temps. .

New ovens are usually pretty moist and it is difficult to get a fire going in them. Just be careful because when the interior becomes dry the fire will want to run away and your refractory walls wil still be wet in the middle. Take it slow, some plastic sheet thrown over the oven will show you if there's water still present from the condensation on the underside. Because you have the vermicrete directly over the refractory it will get hot quicker than if you had a blanket layer. Be mindful of this, if you see steam then you are going at it too hard. You can't do the curing too slow, but you can certainly do it too fast.

[sandybits]

Re: First time 41" clay/homebrew oven.

Thanks Daves,
I think I will go for the heat beads. I am still trying to work out if I should use the little fire lighters that traditionally go with the beads. The ones I know of stink like kerosene.

I haven't used the heat beads before so don't really know if there is another way to light them. Perhaps some sort of blowtorch to avoid the firelighters?

I was also watching some videos on YouTube where a fire lighters is placed under a criss-cross stack of kindling surrounded by larger logs. I'd like to try that once I cure the oven.

[cobblerdave]

Re: First time 41" clay/homebrew oven.

Gudday
Why don't you try a little metho as well it doesn't smell. I use it with twiggs I don't like paper ash floating around my oven. I haven't brought heat beads for a while but I used to buy wax/paper firefighters just at the local supermarket.
Fire making I make a flat Mat of larger wood then using slightly smaller sticks build a "log cabin" on top of this. Charcoal from old fires in the space of the log cabin of twigs and give it a splash of metho and pile smallest twigs on the top. Light in entrance to the oven under the chimney and once it catches push into the middle of the dome with a rake. It's called a top to bottom fire and you can't go wrong.
Regards dave

[sandybits]

Re: First time 41" clay/homebrew oven.

Thanks Dave, I got some heat beads and some firelighters anyway. These ones don't smell but I don't think I have smelt a fire lighter since I was about 12 so they may have changed a bit

I have just been watching a bit about the top to bottom fire on YouTube. Thanks for the tip. It seems if it works it takes away the job of the person lighting the fire. Just set and forget.

I currently have a tomato tin drilled full of holes simulating one of those heat bead chimneys. Its full of heat beads (only about 5)with a firelighter in the bottom. It seems to be working. If that fails I'll put a sardine tin with a little "metho" underneath the tin and try again.

[sandybits]

Re: First time 41" clay/homebrew oven.

I went to the next size up tomato tin (800 grams), drilled it full of holes and chucked 3 fire lighters in it plus about 10 heat beads.

It ended up being a tiny fire and only really warmed up about 300mms each side of it. The dome just above the beads (about 100mms) was about 180 degrees C. The same spot on the outside of the dome was around 40 degrees C.

I've just put the door in to see what happens.

[cobblerdave]

Re: First time 41" clay/homebrew oven.

I went to the next size up tomato tin (800 grams), drilled it full of holes and chucked 3 fire lighters in it plus about 10 heat beads.

It ended up being a tiny fire and only really warmed up about 300mms each side of it. The dome just above the beads (about 100mms) was about 180 degrees C. The same spot on the outside of the dome was around 40 degrees C.

I've just put the door in to see what happens.

Gudday
That spot on the outside of the oven should be the ambient temp. I'm pretty sure 40 C is not Vic temp at this time! That's the moisture transferring the heat through. 100 C water boils , 1 ltr water equals 1600 ltres of steam .... Slowly Slowly . The heat will gradually move that water out. If you force it....
Regards dave

[cobblerdave]

Re: First time 41" clay/homebrew oven.

Gudday
Do you think that coffee tin is only concentrating the heat in one spot on the top of the dome? Might be worth a try in spreading the fire in an open tray. In the way the heat should radiate out the walls as well instead of just the roof.
Just a thought what do you think?
Regards dave

[david s]

Re: First time 41" clay/homebrew oven.

Gudday
Do you think that coffee tin is only concentrating the heat in one spot on the top of the dome? Might be worth a try in spreading the fire in an open tray. In the way the heat should radiate out the walls as well instead of just the roof.
Just a thought what do you think?
Regards dave

I agree, I think you should spread the fire out. The hardest parts to heat are the base of the dome and under the floor. If you have your fire on a tray you can still move it around to different parts of the oven. As well as the heat beads, start throwing on a few finger sized sticks.They will help keep the heat beads alight without causing out of control flame.