I'm helping someone who has had cancer to create safer coils by using cotton instead of silica. We are using protank II and the plan is I will make like 20 coils at a time. As safety is a big concern, we're trying to avoid extremes. So a slower heating is better than a blistering hot instant with tons of vapour etc.
My questions are
1) What is the difference between a micro coil and a regular coil if they are both at say 2,5 ohm.
First of all, remember that wire length and thickness are the only two elements that determine actual resistance. Small diameter coils, by their nature tend to use less wire, and so it is a common misconception (for those new to a good understanding of heating element wire) that this smaller diameter is the sole reason for lower resistance values... when it is, in fact due to the shorter length of wire used.
Moving on - There are two elements at work that make a "micro coil", and either can be adapted independently. The first is size. The mandrel ID will be 1/16" or less. This can permit low resistance with a good coil count, or higher resistance with an extreme coil count. I prefer the former... although some may consider a 10 coil count to be extreme.
The second is "coil compression"... or all coils touching, or at least close enough that they seem to be so. The purpose of the compressed coil is that the heat generated for a given resistance/area can be greater than the sum of parts.
To better understand the value of a compressed coil, consider this analogy. Ten matches, lit and separated by 1 inch per match, generate the heat of 1 match or individual heat source per inch. Ten lit matches, all within one square provide 10 heat sources, "compressed" down to one square inch.
Without going into detail, the alumina (aluminum oxide) layer of Kanthal wire is both thermally conductive and electrically resistive... both transferring heat and preventing, coil to touching coil, shorts.
2) What gauge kanthal is ideal for cotton with the protank II for regular and for micro?
That is open to argument. I would suggest visiting both the clearomizer and coil building sub-forums, and develop a general consensus. Being one who prefers lower resistance, I would use 28 gauge in a vertical coil position.
I am aware that others prefer 30 and 32 gauge in both horizontal and vertical. As coils are cheap and easy... experimentation to determine what is right for you, will break neither you, nor your bank.
3) Which is best in terms of safety and cleaning in your opinion micro or regular coils?
Safety and cleaning? I'm afraid I don't understand how coil design have anything to do safety and cleaning. In my mind, both are as safe as the user is intelligent and both "clean" with a common dry burn.
