In my travels around Australia many people ask me why Heatlie only manufacture barbecue plates from mild steel (otherwise known as carbon steel) and not cast iron. I also get a lot of questions about the pros and cons of different plate thicknesses that we manufacture – “should I get a standard 5 mm plate or go for the 10mm?” These inquiries have become more frequent of late because I believe of the tough economic times we are in; they are looking for “value for money”. People seem to be far more discerning about spending their hard earned money at the moment. So I thought it worthwhile giving some detailed explanation on these points.
Cast Iron
Thermal conductivity is the intrinsic property of a material which relates its ability to conduct heat and both cast iron and mild steel have relatively good thermal conductivity. This makes both materials good for barbecue plates because they heat up very well. However, cast iron has a different crystalline structure from mild steel. It is less dense and therefore more porous when compared with mild steel which results in a number of disadvantages, not the least of which is heat retention.
Heat retention is a material’s ability to retain heat that is applied to it over a given period of time. When used as a barbecue plate cast iron, because of its more porous nature, looses heat at a much greater rate than mild steel. This results in the heat put into a cast iron plate being concentrated almost entirely over the burners. The heat quickly dissipates up into the atmosphere resulting in a cooler surface the further away from the burners you cook.
This is why cast iron barbecues require a higher number of burners per square metre of cooking surface, and use more energy, than a mild steel plate. This causes “cold spots” or greater temperature variations over the cooking area. On average, a Heatlie barbecue will use 40% to 50% less gas than a barbecue with a cast iron plate for a comparable plate size.
Mild Steel
Aluminium is pretty much the best of all metals when it comes to thermal conductivity, that’s why it is used as a “heat sink” in electronic appliances. But it’s not much good as a barbeque plate! The next best is mild steel, or what is commonly referred to as carbon steel. Mild steel also has excellent thermal conductivity and heat retention properties, and whist it takes a little longer than cast iron to get up to temperature it takes a lot less energy to keep it at temperature, the uniformity of heat is second to none, and changes in temperature are easier to control and more uniform.
That’s why they are so good to cook on. Not only do you have greater uniformity of heat across the plate but the temperature of the plate is easier to control as well. You can go from cooking steaks (high temperature plate) to cooking pancakes (low temperature plate) in a matter of minutes.
However, there are many different grades of mild steel so that begs the question which ones do we use for our plates and why?
For all our mild steel plates we use hot rolled formable steel, HA3 for 5mm thick plate, and HA250 for 10mm thick plates. The difference between these two grades of steel is the carbon, silicon, and manganese content. HA3 has 0.08% carbon, 0.03% silicon, and 0.4% manganese, whereas the HA250 is 0.2% carbon, 0.35% silicon, and 1.2% manganese. Essentially the HA250 is a higher grade steel, but of course it is more expensive.
The 10 mm plate is what chefs use when cooking a barbecue, almost exclusively. Why? Because it is by far the best cooking surface. Thermal conductivity, heat retention, and heat control are really second to none with these plates………….it really is the ultimate barbecue plate.
Cooking
There are a number of other advantages of mild steel over cast iron. When cooking on cast iron some of that iron will leach into the food you are cooking which is fine if you are slightly anemic, but is not ideal. Do not use cast iron to cook acidic foods; cast iron is a reactive metal, and will react with the acids.
Never leave food on a cast iron plate for any length of time after cooking. You can use it to keep food warm during a barbecue, but when the barbecue is over, move the food into proper storage container, and thoroughly wash your plate. This is because cast iron also tends hold flavors of food, which can result in other undesirable outcomes.
In the scenario above where you might follow a nice serving of marinated steak with say pan cakes with cream and syrup, if you don’t wash your cast iron plate between courses you will run the risk of having marinated flavored pancakes!!
None of this of course will happen with a mild steel plate, and even if you choose to wash your plate between courses, you will find a mild steel plate much, much easier and quicker to clean than a cast iron plate.
Plate Thickness
All Heatlie mobile barbecues come standard with a 5 mm plate. As I said above, a 10 mm plate made from HA250 mild steel is the ultimate barbecue cooking surface and if you can afford the upgrade then I whole heartedly encourage you to get one………..you won’t be disappointed.
However, a 5 mm HA3 mild steel plate is still very good if you are not able to afford or justify the 10 mm plate upgrade. But there are specific barbecue environments where a 10 mm plate is, without question, a must.
Mild steel plates will warp or buckle if they get too hot and the bigger the plate the more susceptible they are to buckling. For example, if you were to leave your burners turned on high for more than 4 or 5 minutes without food on the plate, then chances are you will buckle the plate. This is particularly so for the Heatlie 1150 series of barbecues because of the width of the plate, it is well over a meter.
Many Heatlie 1150 barbecues are used in a semi-commercial environment by sporting clubs, community clubs, churches, and schools, etc for fund raising barbecues. This means that many different people are using the barbecue some of whom may not be aware of the risk of buckling with a 5 mm plate and leave the burners turned on high without food on the plate resulting in warping or a buckled plate.
So, if the barbecue is purchased for this type of use then a 10 mm plate is a must, it’s almost impossible to buckle. This is really important because plate buckling is not covered by either a domestic or commercial warranty. Why? Because if the operating instructions are followed carefully then the plate will not buckle.
If you require any further detail on our plates, or our products in general, then please contact us as per the details on this web site.
Author: Terry Reeves, Marketing Manager, Heatlie BBQs