Checkout out Blossom Recipe Page to learn about other factors with croissants.
Bloom the Yeast: In the process of blooming the yeast, the directions call the baker to use a bowl. For this step, you would want to use a metal bowl as it is a good conductor of heat, allowing the energy to pass through easier. This part of the procedure then says to add warm milk, seeing as this process requires yeast, yeast activates at an accelerated work when mixing with warm liquid. That is why it is important to add warm milk rather than cold milk. This causes the dough to rise more efficiently. This step also requires the liquids to be used before solids. Liquids are necessary in order to hydrate the proteins which in turn the water is absorbed providing that chemical change that is needed to make the croissants. Contributing to the texture, the liquids allow the solids to have a better aesthetic as well as taste.
Make the Dough: This step asks for the baker to use salt, you would want to add flour and salt to the bloomed yeast because salt works to tighten the gluten strands present in the bread. Allowing for a stronger dough which is needed to make the croissants last. Allowing carbon dioxide to be held more efficiently. You would let the dough knead after adding the flour and salt to develop the gluten. It is incorporating air which then allows the dough to get to its next stage. By wrapping the bowl, you are creating an environment for the dough to continue developing. This entire process is so that you may get a working dough.
Prepare the Butter: The plastic is used in these steps as it can typically withstand different varying temperatures, more specifically colder and warmer temperatures. In this case, wrapping the butter and flattening it, means the butter can be arranged a lot easier as its height of it is deconstructed. By flattening it, the heat does not have the transfer to the center at a longer rate, you are able to transfer heat all throughout at a faster rate.
Laminate the Dough: The floured surface is used so that the dough does not stick and become stuck to any surfaces. Flour and other dry ingredients are water seeking which seals moisture unless there is a good amount of coating separating the two. Putting the current product in the fridge, allows for the dough to be preserved, especially since you have a perishable such as butter mixed between it. You do not want the butter to be melted before putting it inside the oven because then the outcome will be different. On top of this, since yeast is a lot more active in the presence of warmer environments, putting the yeast dough in the refrigerator slows the activity over the years, causing the dough to rise at a slower rate hence the 1 hour wait time.
Bake the Croissants: The reasoning for continuously rolling the dough out is to create even thickness all around rather than concentrated in one area. The eggs added also then help with the dough when rising as the egg act as a leaving agent. That egg mix tenderizes the crumb and lightens the texture. Parchment paper is used since it is heat resistant meaning it will not cook nor mix with your croissants. You will want to use a metal bowl given they are good conductors of heat and then can be used for oven usage. At 400F, it is enough time to bake it and rise, but not overbake which would burn it. But in order to prevent the dough from becoming too hard, you then want to turn the temperature of the oven down. In this process, you have started the initial reaction and then further develop the dough but at a cooler temperature.