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Avoid harshness, the physics of hookah

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Hello everyone, this is my first post and I would like to introduce myself as both an avid hookah smoker and physicist. Much of the information in this post will seem like common knowledge to hookah veterans, but even experienced smokers might find some of this interesting. 
No one likes a harsh hookah, but to many why this occurs remains a mystery. For many smoking hookah is a hit or miss endevour and people seem to get wildly variant results from bowl to bowl. However, with a little experimentation and proper scientific method (change one thing at a time) one can drastically improve the quality and consitency of the hookah experience. First we must ask, what makes a hookah harsh? There are two main causes: too much heat (this causes the dry, pinching sensation in the back of the throat) or too much carbonized matter in the smoke (this causes the "harsh" taste and usually forces a coughing reaction). As we will see these two are closely related, too much heat makes the tobacco burn as opposed to smolder and puts more "bad" particles in the smoke. But it is still possible to have one with out the other.
Managing Heat: Heat must be controlled on two ends, pre and post water filtration. First I will deal with how to maintain cool smoke proir to its entry into the water. This mainly has to do with the amount of heat on the bowl, we want the tobbacco to be heated and smolder evenly, never to actually burn like in a cigar or cigarette. The main factors responsible for heat on the bowl are air flow across the bowl, and amount and postion of heat sources on the bowl. For air flow, you want a moderate amount, too little and all the heat will get "stuck" at the top and burn the tobbacco, too much and the coals will get over stoaked and burn the tobbacco. Hence, you want a loose pack that allows the heat to be drawn deep into the bowl, as well the optimum solution for holes in the foil. To keep the tobbacco cool, one must learn the proper amount and postion of holes in the foil, as well has how to best orient the coal throughout the course of the bowl. This is different for every hookah and every different bowl design, and can only be learned through individual experimentation. However, it is a general rule the the higher the depth to surface area ratio of the bowl, the more central heat the bowl can tolerate. Most female bowls have a low depth to SA ratio, keep the coal to the edges. Most males have a better depth:SA, so keep the coal more centralized. Also experiment with amount of coal (very important with lemon/orangewood coals), and if you get too harsh a smoke from three kings style coals, try inverting them so that the smaller top portion of the coal is in contact with the bowl. Also, water level can effect the temperature of the bowl. If the down-tube (the bottom part of the stem that goes in the water) is too deep, when you cease hitting the hookah it will fill with water and drive air up the stem re-stoaking the tobbacco which can exacerbate an already harsh bowl. This is why you may see smoke puff out the top when you stop inhaling. Normally this is not a problem, but many try to fight harshness by raising the water level, and going too far in this direction is a bad idea. My next post will focus on how to keep the smoke cool once it has left the water, and how to manage the amount of particulate matter in the smoke
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Physics of hookah, Managing Heat Part 2:
The main factor responisble for cooling the smoke is not the water as many think, it is expansion. The temperature of any gas is inversely related to its volume. This means when gases get bigger, they get cooler. This is why longer stems and hoses and bigger bases give cooler smoke, more room to expand to. However, water still plays a role in cooling the smoke both directly and indirectly. The more water, the more resitance to your pull, this means you work harder and accelerate the air more, the faster moving air expands quicker and cools more effectively. This means you should strive for a balance, too much water and the effective expansion area in the base is comprimised. Too little and you risk slowing down the air flow, and miss out on slightly better filtration. Also, adding ice can make the smoke marginally cooler, but you might want to avoid this for other reasons I will bring up later. You should also look for hookahs with longer stems and hoses, up to a certain point, this will be discussed later.
Managing Particle Level in Smoke: This is kind of a sticky subject, the thickness and quality of smoke is entirely dependant the amount and type of particles in it and everyone loves thick hookah smoke, so why cut down on the amount of particles? Well, too many carbon and organic particles can make the smoke thick but undesirerable. The smoke is too whispy and translucent and poor for blowing rings because it doesn't "hold" together. What you want is the thicker looking, but less particulate white billowing smoke that is a higher percent water vapor and CO2. This smoke is more condensed and optimal for ring blowing and smoke tricks. THere are really only two feasible controls for this, water temp. and hose lenght. In the hookah, water is a solvent, the particles from the smoke get dissovled and go into solution with the water, removing them from the smoke. Like any solution, it has a saturation point at which no more particles will go into solution. The higher the temperature, the higher the saturation point and the more filtration occurs. That's right, it may seem counter intuitive, but hot water should make your hookah smoother than cold water. This also means the water should be changed as often as possible. Also a longer hose makes the hookah get less harsh because many of the particles get stuck on the inside, but too long and it will start to affect thickness. Finally, adding extra honey to your shisha, especially if you buy nakhala can result in better smoke because it moves the CO2 levels to a better range.
Thanks for reading this lenghty post and don't forget, the best thing you can do is experiment on your own and see what works best for you. If I get positive feedback on this you guys can also expect a post on the physics of smoke tricks which will explain the physics behind ring blowing, and how best execute smoke tricks like the ring-through-ring, the heart shaped ring, blow-back rings, and the french inhale.
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I've been hooked on around 10 bowls a day for the last 9 months. 
I know that's not healthy,  but my hobby has turned into a habit
and I can't seem to be able to stop.  I've either given-away or
sold 8 hookahs sofar in an attempt to quit,  and I always end-up
buying a new hookah. 

I'm hooked on the hookah 
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holy crap Lord, thanks a TON!  we had a discussion about the "size" of holes and how many to put in the bowl....what are your thoughts on the physics of this and how it will help the smoke...? do you want a lot of tiny holes or less bigger holes, say the size of a toothpick?  Is it good to have them evenly poked around the bowl or randomnly?
Thanks for all of your time, these are really helpful!!
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Lord Dorian, this is an excellent post, though I do have a question tha
tmight be impossible to answer specifically. It's been quite a while
since I've done any hard science, but I have a question in relation to
your statements about water temperature.

While it is certainly true that water with a higher temperature can
hold a greater quantity of stuff in solution, does this really make an
appreciable difference at "feasible" temperatures, (like for example,
does 100 F water filter appreciably better than 36 F water?)

I generally use ice in the water, but i'll have to experiment to see if
a warmer water yeilds a noticably smoother smoke. Thanks for the tips.
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Well wyteboy, this largely depends on the type of hookah and bowl. On my small mya-saray acrylic, a small number of small pin sized random holes seem to work best. However, my tall m-s bohemian works best with as many toothpick holes as possible. And the rotator hookah my friend furnished from egypt is always smoked with nine toothpick in a 3x3 box pattern. It also depends on the coal type, 3 kings and poorly made israeli/egyptian coals generally require smaller holes to cut down on carbon intake and embers falling in and potentially burning the shisha. Also some natural coals (lemon/orangewood) produce a lot of ash which can get sucked down larger holes. Generally, smaller holes mean more distinct flavor, but less thick smoke (less particles in the smoke so the particles resposible for flavor are more noticable). But, with adjustment you can get great smoke without comprimising airflow or taste. Also, lateral knife slits are excellent because they allow alot of air while making it hard for ash/carbon/ember to get through. I have been experimenting with those lately with excellent results. 
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bcoll, you are right to suggest that the change in saturation per degree is marginal. However, the cooling difference that is provided by ice is also somewhat marginal given the time the smoke is in contact with the water. Also, keeping the water hot is a problem since warm water will come into equlibrium with room temperature sooner than ice water, which has a constant cooling source. However, since many of the particles in smoke have an extremely high affinity for water (you'll notice it doesn't take many sessions to discolor hookah water), I belive that the drop in solubility caused by ice is greater than the positive cooling effects. However, this is largely a matter of preference, you may be more sensative to the heat based harshness than the particle based harshness, if ice works better for you stick with it. But you should try warm water because in my experince it has a noticable effect on the smoke quality.
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Again, Lord Dorian, very interesting and informative posts. This has me
thinking about achieving an optimum balance. I don't think it will
matter terribly much for my large 30 in rotator, as it has a rather
long air path, as well as a rather large vase. But for these junior
hookahs that I'm interested in using for the sake of portability /
quick set-up, the relatively short stem length and relatively small
vase might exaggerate the differences between warm / cold water, as
well as different hose lengths. Things to ponder when I can smoke again
in a couple of days 
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Hey Lord, question for you...
OK, I tried a different foil method today.  (also going to post this in the lord dorian thread to ask a question).  Instead of using about 18-22 holes the size of the thickness of the toothpick, generally in NERVs pattern or so, today I tried probably like 50 holes just the size of the very tip of the toothpick, almsot thumbtack size sort of.  I did in vertical lines down the bowl in 5 separate lines, then a few bunched up groups of holes in other areas.  I smoked GS AF straw with 2 goldens.  The smoke was AWESOME.  I still stand by that the GS AF straw is a little less "sugary" or sweet than the regular AF Straw, but I mean more with the foil pattern.  Once it got going I got a real good, thick white smoke with no harshness or burning on the bowl WHATSOEVER.  I may stick with this method from now...The holes didn't really get plugged up with ash, though I wonder if I was using Nour if they would.  Would this make the bowl almost unsmokeable?
Also, is it possible to still get great thick smoke with tons of flavor with a lot of tiny holes or was this one time sort of an abberation?  Does this lead to MORE or LESS actual "burning" of the ma'assel as opposed to smoldering?  I found the crisp tobacco was more dried out and "crispier" with this method I think than with the bigger holes.  I am not sure which way to think, on one hand it would seem bigger holes would allow more heat in, causing more burning but at the same time I can't help but think they would simultaneously let more cool air in causing LESS burning, LOL!
Help, "doctor of hookah" :)  WHich was is the best to get the least burning, tar or "bad particles" in the smoke? tiny holes or bigger holes?  WHen I smoke later tonight I think I may use the tiny hole method again.
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I've often had great results with tons of pin holes, especially on shorter hookahs. On my acrylic m-s I use a pattern similar to the one you described. This should let less carbon from the coal in and make the flavor more distinct, and as long as you make enough, the smoke should be good too. However, if your hookah rips super tight (if you use wet toliet paper or paper towel to gasket instead of rubber grommets or you own a mya-saray that still has all it's internal head valves intacted) you might not be able to get a good airflow and the smoke may suffer. The only situations (in my experience) which warrant large holes are when using natural coals (the ash tends to clog small holes, and they give off less heat) or on a large hookah, maintaing a gap between the shisa and the foil. However, I would recommend getting a fillet knife or razor blade and trying 1/2-1 cm lateral slits, these let in a lot of air in the long way, but are too narrow for most embers/asy to get through.
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OK, as this is being posted I have two identicle mya-saray acrylics burning al-waha 5-star. Both are operating on orange wood coals and have the same bowl. One has the high frequency pin hole punch in a pattern similar to the one above, the other with 6 1/2 inch razor slits in two staggered lines. I am thirty five minutes in and the pin-hole has burned well with no noticable harshness and good flavor. About ten minutes into the slit bowl i got hit with some harshness, but smoked through it. After that, the smoke was much thicker and more condensed than the pin bowl, which still had good smoke, but a little more whispy. In my opinion, the pin bowl produced less harshness and slightly more defined flavor. The slit bowl made much better smoke, but the flavor got a little over powered (it was still very good, just not as defined). Since I primarily smoke to do tricks, I perfer the slits, it also had a much easier pull, and the flavor was not bad. However, you may have to smoke through a little harshness in the beginning. Surprisingly, the small holes continued to draw well despite the ash from the orangewoods, probably because I made an effort not to move them ore blow off the ash, which often simply lodges it in the hole. (also note I used an actual pin so my holes may be smaller than those made by wyteboy)
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lord I have a hookah about 27 inches long and the base makes up about half of it... my hose is long maybe 8'... I have both a large bowl and a regular sized bowl... I want a balance between thick smoke and flavourfull smoke... what do I do? I am using 3 kings charcoal. I was thinking a mixture of tiny holes and some slits? lets say, tiny holes everywhere, and 4 slits right on the edges of the bowls, 1 at 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock. does that sound good to you? and how much am I supposed to pack a bowl when I used the tiny hole method? and how many coals? thanks inadvanced lord... of you reply I will update you...
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  • 1 month later...
I just had a weird experience. The flavour was somewhat metallic, but that doesn't quite explain it. I use aluminum foil at the top of my hooka. I am just curious if the side pointing up on the aluminum foil makes a difference? Normally there is a shiny side and a dull side. I know that to clean my bbq, we cover the grill with aluminum foil so a certain side is pointing up so that the broken bonds somehow clean the grill. I am wondering if this makes a big difference. Any help is greatly appreciated!Ryan
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[quote name='rcgoodfellow']I just had a weird experience. The flavour was
somewhat metallic, but that doesn't quite explain it. I use aluminum
foil at the top of my hooka. I am just curious if the side pointing up
on the aluminum foil makes a difference? Normally there is a shiny side
and a dull side. I know that to clean my bbq, we cover the grill with
aluminum foil so a certain side is pointing up so that the broken bonds
somehow clean the grill. I am wondering if this makes a big difference.
Any help is greatly appreciated!


I know pretty much everyone here will tell you to use shiny side down,
facing the tobacco. Even if you don't do this, it shouldnt give you a
metalic taste. The only way to get a metalic taste from what I hear is
getting residue, water and other crap in the hose. Most hoses are lined
with a long spring type metel, and non-washable hoses will give off a
metalic taste if junk its in them. Look out for this.
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I have a question regarding cooling the smoke and filtering it.
My no. 1 hookah to get next is chiller syrian with extra 'ice' chamber on the top where you are supposed to put ice. Do you think that ice will help reduce heat even more (sounds logical or scientific if you will). I also had this idea. What would happen if you put hot water in the top chamber, and ice cold water in the bottom? This way solubility at the top would be such as to allow for greater filtration of particles, yet it would be cooled down in ice cold water?
Does this makes sense? I really think that extra ice chamber at the top can be usefull.
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