Especially in case of the Dräger Panorama Nova Dive defogging plays a role as this mask does not have a special defogging gas flow. So you need some defogging agent. Of course, you can find many commercial products for fighting the fog. The slight problem: large amount of unknown and undeclared additives and lots of annoying scent. Think about all this concentrating in your longs over the time of a dive, such as one and a half hour. No, thanks.
Ironically, there is much fog when it comes to defogging agents. Luckily, it's really easy to avoid this situation if you know where to look for suitable agents...
Defogging agents seem to be the modern-times complement of medieval pastries or the infamous hog maw: no one really knows what has been stirred into it. I'm still waiting for a UK-based reseller about the proper declaration for his defogging agent ... but that's a different story.
Problems with these agents are eye irritations and allergies. In contrast to diving with a half mask, in case of a full mask you are inhaling the volatile ingredients of the defogging agent all the time during your dive. In addition, these agents usually try to distinguish themselves from the competition by scenting as strong and bad as possible. Do people really believe in strong scents representing cleanness?
With so-called nano particles in a defogging agent it gets really dangerous. These smallest particles are by their very definition able to easily cross any tissues to enter your lungs and blood vessels without hassle. But these particles have nothing to do in my body, clearly defined medical treatment aside. This dangerous practice in the diving sector reminds me of the Doramad radioactive toothpaste: incompetent merchants have not the slightest clue of what their goods are able to cause and instead claim wonders. I've just met such an example of a clueless sales representative with exactly that Doramad attitude. To his favor, let's assume Hanlon's razor.
Of course, there are valuable and safe applications of nano particles; but not with mask defogging. No seller of these nano particle defogging agents does any real declaration: no one knows how volatile these particles get after the solution they swim in dries and they stick to your visor. No one has any clue how many of these particles drift off the visor and enter your lungs and then blood vessels. Declarations such as «biologically degradable» are utter nonsense. They are deposited in your tissues, that's biologically degradable. There are no real scientific analyses.
If you remember those nano car finish: this will eventually fix all these particles, so they are not getting volatile. But with defogging agents, there is just a fluid acting as a temporary solution that dries when applies. While diving, there is sweating and liquid in the gas within the mask. No one knows how much of the particles will get washed out from the visor and enter your breathing gas. Casino royale? You bet!
Simple & Clean
Okay, it's common knowledge that your spit is a good antifogging agent. As is liquid soap and dish liquid. In my case, spitting the Dräger visor isn't reliable in keeping the visor free from fogging. And if you go for a typical commercial liquid soap or dish liquid product, their most important property is to scent like hell. And they contain numerous filling and additive agents, for whatever reason of maximizing profit. But I don't want to breathe in this shit into my lungs, not while diving.
Darth Vader's Mask Defogging Agent.
After the tragedy with the totally incompetent sales representative I strode into a health shop and looked for cleaning agents. And yes: they have dish cleaning without any additives and without scent. There are several products available, but take care as some of them actually add unnecessary additives and scents despite being health products. For instance, with Spinnrad you are on the safe side, however.
Luckily, next to the dish cleaning they also sold all those tiny cups and bottles for plastering your face with unknown essences. The small spraying bottles were almost perfect, so I got them. Fine for spraying my full face mask in preparation of a dive.
I'm simply filling in some agent into the bottle, filling up with clean water. That's it. Shake it slightly, and it's ready for use.
So far, my simple defogging agent has proven to be effective even in difficult situations: rainy days, everything's wet, still defogging my mask. Even if I have to wait on land for some time after donning my Dräger. The commercial agent I used before was already loosing completely under such conditions. And my simple agent does not scent at all.
The commercial shit has met the trash can. I still got no declarations from the company importing their defogging agent: they are not responding at all. Go figure and judge for yourself buying anything from such a company.