Show us your Door Thread

[dfhood]

Stainless pieces upcycled from junked commercial cooler, stainless rivets and handles (may need to use potholders -_-), ceramic glass, ~2.75" ceramic insulation, 5" thermometer from forno store inset into 2" hole, and probe guard on back. Would've been nice to weld this door together, but did what I could with what I had. Hoping it will help to retain heat decently, despite the amount of glass. Looking forward to using it later this month. Planning to also make a simple separate door (thin, lightweight) for easier airflow control if desired.
Door pictured is intended for retained heat baking, with visibility using a flashlight.

[Sixto]

The aluminium is only for my outer door. Aluminium does not play that nicely with heat. For insulation, encapsulated in the steel box on the inside of my wooden door, furnace blanket works really well.

Got it. thanks Mark! I'll probably do two doors, a stainless steel sheet with no insulation and a perlite/refractory cement like what David described.

[MarkJerling]

That sounds great for the Stainless or Aluminum, Thanks Mark! Any suggestions about the insulation material if I can't get calcium silicate???

The aluminium is only for my outer door. Aluminium does not play that nicely with heat. For insulation, encapsulated in the steel box on the inside of my wooden door, furnace blanket works really well.

[fox]

I use a very similar solution to David but use vermiculite board for the backing, I use vermiculite and metal for the inner door and vermiculite and wood for the outer door.
vermiculite board is used to line wood burning stoves and is readily available at associated stores.

[Sixto]

That makes perfect sense! Thank you for your detailed response David!

[david s]

Because earlier versions of the insulating panel were not really strong enough, they wore out with a fair bit of use. I had used mill board which is about as strong as calcium silicate board. The cast panels I have developed use a 4:1 mix of sand and calcium aluminate cement to a depth of around 3mm which becomes the face of the panel sitting against the oven mouth. I then immediately make up a mix of 125ml calcium aluminate cement,500 ml sand and 700 ml medium grade perlite and some AR glass fibres and some pp fibres. For added strength I also embed three 6mm round steel bars into the centre of this layer for added strength. This is enough to fill the remaining 17mm of mould thickness. On remoulding 24 hrs later I wrap the panel in plastic for a further two days.
One big advantage of calcium aluminate cement, apart from its ability to withstand higher temperatures than OPC, is that it achieves its full strength after 24 hrs, although I always give it a couple of days to be sure. It has taken me a long time to arrive at this brew because the panel can be made stronger with the addition of more cement, but that reduces its insulating capacity. The richer mix for the face that faces the heat and sits against the oven mouth does a good job of strengthening that part. A metal facing is an alternative solution, but because it is so conductive is working against you to work as an insulator. It also increases the door weight substantially and introduces a third layer of material which adds to the fabrication costs in terms of labour and materials.I have considered doubling the panel thickness but that would increase the weight, make handling the door more difficult and the door would require two handles rather than one. This modification would also increase cost of materials and labour. For folk making a one off door the extra labour and materials are probably not a factor.

[Sixto]

...My solution, which does have its drawbacks, is to use a 20mmm wooden door with a cast 20mm insulating panel bolted to it using 3/16" 316 stainless bolts, being as thin as I dared to reduce conductivity, and with the panel held away from the wooden door with high temp silicon to reduce heat travel by conductivity...

Thanks DavId!, I like the wood look and functionality also. Can you share more details about the cast insulated panel? is that a perlite/vermiculite and cement mix? If so, what ratio would be strong enough to face the fire directly, and would you recommend a leaner, more insulating mix if you had a metal layer facing the fire?

[david s]

I came at it from a different angle. I like the look of a wooden door as it's traditional for Italian ovens. But the problem is that it burns if it gets to 250C.The Italian's solution was to soak the door in a bucket of water prior to fitting it.If it charred up badly they'd just make another.
Using a highly conductive material like stainless or aluminium as a facing for the door, where you are wanting it to insulate seems counter productive.
My solution, which does have its drawbacks, is to use a 20mmm wooden door with a cast 20mm insulating panel bolted to it using 3/16" 316 stainless bolts, being as thin as I dared to reduce conductivity, and with the panel held away from the wooden door with high temp silicon to reduce heat travel by conductivity.
I've arrived at this solution mainly due to fabrication time and appearance.
The insulating panel needs to be fairly light and insulating, but at the same time durable. This is not easy because you can make it stronger but that reduces insulation value. Making it more insulating makes the panel lighter but very susceptible to wear and damage. A compromise somewhere in the middle is how I now do it.
I works pretty well, but you can't place the door after a pizza cook up and expect it to hold the heat the next day because the door will burn. Because my oven is small it's no big deal to flash it up again, but for roasting and baking with the oven below 300C, the 20mm of insulation does a fine job of both holding the heat and protecting the timber door.

The one handed operation is also a bonus with the door's total weight only 3.3kg

[Sixto]

That sounds great for the Stainless or Aluminum, Thanks Mark! Any suggestions about the insulation material if I can't get calcium silicate???

[MarkJerling]

Id love to get recommendations from the experienced builders regarding door insulation, I'm having a hard time sourcing cal-sil board, so I'm considering 10:1 perlcrete or rockwool board (called ProRox 960 which indicates an R-5 per inch?) whichever I go with would be fully encapsulated in stainess steel. I guess I'm trying to see which one would do a better job of insulating per inch of thickness...

I will probably end up with 2 doors, the insulated door to keep residual heat for as long as I can, and a plain SS plate door to control air/smoke and minimize rain infiltration.

A question about Stainless, i've read that it warps, is there a minimum gauge I should use for the inside face on the insulated door... what about if it's a plain non-insulated metal plate?

Thanks to all for a helpful thread!

See my post #141 above. I used either 0.9mm or 1.2mm thick stainless steel, I can't remember which. Following below my post, a few posts down, is a similar design to mine, but made nicer than mine! While the stainless steel sheet facing the oven warps slightly when the oven is hot, it soon returns to flat as the oven cools.

I now also have a thin aluminium "outer" door which I use to keep the weather out.

[Sixto]

Id love to get recommendations from the experienced builders regarding door insulation, I'm having a hard time sourcing cal-sil board, so I'm considering 10:1 perlcrete or rockwool board (called ProRox 960 which indicates an R-5 per inch?) whichever I go with would be fully encapsulated in stainess steel. I guess I'm trying to see which one would do a better job of insulating per inch of thickness...

I will probably end up with 2 doors, the insulated door to keep residual heat for as long as I can, and a plain SS plate door to control air/smoke and minimize rain infiltration.

A question about Stainless, i've read that it warps, is there a minimum gauge I should use for the inside face on the insulated door... what about if it's a plain non-insulated metal plate?

Thanks to all for a helpful thread!

[Dino_Pizza]

Thanks UtahB,
and the final door did not have all 8 of those SS u-brackets as on my test door out of cardboard, just 6 you see holding in the insurance in one pick. That six made it sturdy enough.

[UtahBeehiver]

That's a good way for non welders to build an insulated door. Thanks for sharing on the blog.

[david s]

Hi David, nice to chat with you again.
The door is 12.5 pounds (5.7kg).

DAY1 …..After a pizza fire, it was well saturated at 650°F when the door went on.
DAY 2 ….12 hours later it was 470°
DAY 3……24 hours later it was 250°
(I did cooke a brisket later on day 2 and it was still 400°F)

The put the IR thermometer gun on the face of the door each day and it was 150° on DAY 1&2 and 125° on DAY 3.
My oven arch walls were also 150° the 1st day, same as the metal door.

This was my one and only use of the door. I’ll make notes again next time,it is summer and quite warm here.
Thanks, Dino,

That's pretty good 5.7kg is pretty manageable. Can you touch the bolts that run right through the door on the outside? I assume not as the temps you recorded suggest.

[Dino_Pizza]

Hi David, nice to chat with you again.
The door is 12.5 pounds (5.7kg).

DAY1 …..After a pizza fire, it was well saturated at 650°F when the door went on.
DAY 2 ….12 hours later it was 470°
DAY 3……24 hours later it was 250°
(I did cooke a brisket later on day 2 and it was still 400°F)

The put the IR thermometer gun on the face of the door each day and it was 150° on DAY 1&2 and 125° on DAY 3.
My oven arch walls were also 150° the 1st day, same as the metal door.

This was my one and only use of the door. I’ll make notes again next time,it is summer and quite warm here.
Thanks, Dino,