The insulation of a wood fired oven in its construction is extremely important in ensuring that the oven can reach the optimum temperature and operates in an efficient manner. The best pizza can be prepared only at the high temperature of around 750 F (500 C). The exterior of the pizza oven should be cooler than the temperature of the air there and if this is not the case it may be because there is insufficient insulation.
Before construction of the oven insulation can begin the internal oven chamber or dome must be completed. The dome is where the fire of the oven is built and heat primarily radiates. To maintain the heat in this cooking area, insulation is placed to produce a barrier which prevents the easy convection of heat away into the atmosphere. The shape and sizes of the oven does not directly influence the type of insulation used. The thicker the insulation however generally indicates the efficiency and potential use of the oven. The basics of insulating involve wrapping of the oven, chimney, and vent by the use of the insulating fire blanket or other types of medium. If using a concrete and vermiculite mixture a wire form is first placed over the dome to create a base for placing the mixture. The vermiculite and Portland cement are mixed together well before adding water to it. A paste is prepared and a layer of it is pasted on the oven such that it holds firmly to the wire frame. The vermiculite concrete is used all around the dome of the oven, chimney and vent.
For insulation of pizza oven this option is quite costly and most applicable for wood oven with limited space. Several grades of bats are available in market. If it is wood oven, you can use lower grad. Higher grade is used on hot face. You have to use ceramic fiber around the walls and top as well. One thing you have to follow that you should not put any layer of mortar or other layer on it because it will degrade the insulation capacity.
At the time of insulating pizza oven with ceramic fiber, you should were gloves, respiratory masks and goggles because it produces sharp dust particles. This dust particle may cause allergy to you. Sometimes ceramic fiber is found in form of fluff. You can push fluff into narrow areas. If you desire to insulate your pizza oven with ceramic fiber, you can go to local refractory shop and ask them for ceramic fiber. If you don't know how to insulate with this materiel, it will be better to hire professionals.
As with fire bricks, insulating fire blankets are generally utilised in the commercial construction of industry kilns or large ovens. The blanket can be purchased from suppliers which deal primarily in these high heat tolerance refractory products.
Vermiculite is gray brown mineral, which is shiny and flat in natural state. When vermiculite is heated, it pops creating air pockets. For this expand form, it doesn’t burn at all. For this exceptional physical property in high temperature, it is used as insulating materials. It is also seen to be used in making pizza oven insulated. For using as insulating material, it needs to get mixed with cement. After mixing with cement, it will be lightweight concrete, which is applied on dome of pizza oven to make it insulated. Normal application thickness of vermiculite is 4" on oven dome.
There is no adverse effect of using vermiculite on human health. But if there is asbestos in vermiculite as impurities, it will be a matter of health problem. If this asbestos is inhaled directly during installation, it will cause problem. So it is better to use mask and goggles when it is used to insulate pizza oven.
Vermiculite is extensively used in gardening as both a soil improver or soil medium replacement in hydroponics. Large bags of vermiculite can be purchased at hardware stores, garden landscaping suppliers, and especially at hydroponics suppliers.
Mixed refractory insulating material contains vermiculite, Portland cement and lime where the mixture is: vermiculite : Portland cement : lime = 13:1:1. Following this ratio all ingredients are mixed with small amount of water. This mixture will be solid with soft in nature. Then it is applied on the dome of pizza oven. When it becomes dry, it acts as insulating material. Normally, this mixture with 2.5cm thickness is applied on pizza oven dome for ensuring insulation.
how do you render the fire blanket if you are not to put mortar on it? Confused now.
Leave a 2" space between the fire blank and the mortar.