Cleaning waste motor oils for oil burning type boilers

[tcmtech]

Yes and where you live its considered reasonable for any novice to make high explosives and set them off with next to zero knowledge.

Yes, My country, my rules. Your country, not my rules. You like your nanny state, we don't! What is so hard to follow there?

Direct flame cracking on a small scale is not safe, on a large scale its being phased out.

Safety is relative, You have a nanny state mentality we don't have. Got credible proof and timelines and how they are being phased out and to what alternative system they are going with that's in any way relative to your thread?

Your only mention is having plenty of BTU's at your disposal and references to used tires etc. The fact you mention open flame cracking i would consider proves my point your thinking of open flame.

And again, Your assumptions are not reality nor are your concerns mine. I will use whatever method I find most practical to work with and that is all there is to it. You won't change my mind by the methods you are going with now. Especially with nanny state based excuses derived from your assumptions that do not fully apply to me.

Other countries read this forum, the advice your giving pertains mainly to one part of the world. Your information is extremely dangerous and while you may care, i certainly care if people think its perfectly safe to do just because you said it was.

Yes, Welcome to the internet where everyone has to take their own local rules in consideration when looking at what others suggest from anywhere else in the world. Your laws are not everyone's laws and most people know that. Same with those who post information to the internet. I don't care what your laws tell you to do or not do and I most certainly have zero concern to cater to things that do not matter to me here.

Do you think any of your postings would pass in some highly regulated country? Probably not so do you censor what you post anywhere anyway to the maximum level, just in case, somebody from such a place would ever manage to read what you posted? Everyone's standards for safety or anything else are different so learn to deal with your safety and whatnot issues on your end. Nobody but my owns safety is my problem and I expect no less actions for others and theirs.

Again another big difference between where you live (which is almost third world in its approach to environmental issues) and the rest of us, its better to clean an oil to the point it dosnt need to be out doors to be safe or meet regs, rather than just take a lazy dont care attitude and spew toxins everywhere.

And I should care what you or your nanny state thinks, why? Do you make an effort to adhere to other countries various rules, even if they don't apply to you and you seen zero validity in them? Those people who live there think you're some sort of monster too, just as you do me, because you're not living up to their standards and don't care too as well.

I tried all that in the begging by posting papers in other threads, it was clear you were unable to understand the content. So rather than try and make you look silly i stopped posting them,

I'm pretty sure that's not what happened and we both know it. Everything I read pretty much proved me as right as it proved you and you didn't like it. How many times did you pull up my own links and proclaim you were right, for something I already pointed out and agreed with you on or that uttery refuted your own claims ,but you claimed proved you right and me wrong anyway? Too many times to not see the blindness in your views. Just as you are hypocritically doing here now by saying your views of the world count but mine dont while you also have to dismiss others rules to live your life the way you do.

You more than anyone should be aware i am ALWAYS able to back what i say with high quality scientific papers from quality journals, i unlike yourself do not rely on random websites with no credibility.

Too often it's been the other way around and you know it. Plus, if you dismiss mine because you don't see them as valid I get to do the same to you. I play by the very rules you play by so if you don't like my game then don't make rules you don't like to be held to yourself.

I havnt called you a liar or suggested you are one, other words spring to mind way before those ones, but people can judge on what is posted to back what you say.

You read between the lines to find things that are not there so I am doing to you. You don't like it dont play it.

As for what others do, I let them decide what's right or wrong for them. I don't try and dictate what they should think or believe based on my own standards. They have brains and I trust they can use them on their own to decide what's best for them without me holding their hand all the way. I don't know what they think and I don't care to try and imagine them for them. They have their own lives so they get to live them as they see fit.

I notice you mention my age yet again, i am sure you think this is some kind of trigger for me, i can assure you it isnt. I am proud of my age, i am proud that despite not doing a degree first i was excepted on and i am doing extremely well on a post undergraduate degree, i was allowed to do this because of the depth of both ability and knowledge i displayed to a panel of highly educated people.

It's not to trigger you. It's to point out to adult that you are still a kid of limited real life experience and thusly they need to take your advice accordingly. Adults get it and its value and importance. You like to point out things you think matter to others views of my credibility so I get to do the same to you in return. You don't like it, don't do it to others or learn to live with it.

Those that actually know me, and indeed one well respected member on here who is in business with me, will tell you that my attention to detail and research skills are way above normal. That might sound arrogant and to others i am sorry if it does, but the point is when i post on these types of subjects i know what i am talking about.

Exactly my point. I don't know you or your real life or who you work with anywhere and thusly don't try to read anything negative into your life just because it fits some wild self justifying imagination of mine but I do know your still a kid of limited life experience just the same (but you do it to me to fit your false narratives constantly) . Ambition and idealisms are not a substitute for long hard earned experience and wisdom.

Anyone can burn oil or make methane, but try and so it efficiently,safely and within all MODERN legal frameworks.

Yes, Your/their own locally applicable legal frameworks. Yours don't count where they are not a part of someone else's system of governance. Yo may not like it but the fact is much your laws and personal beliefs can pound sand in their value where I and countless others live.

I am sorry for the above, i tried in the beginning, in other threads to provide decent back up references. Even when it became clear who was working from facts and who was not, the other poster is insecure and will not admit it.

Now you're just projecting, again. Nobody derailed your thread over butthurt feelings but you and we all can read that. In fact as you have been called out other threads for, you seem to be the key factor in your own threads running off course (ones I have had zero participation in no less) and always for your need to do what you are doing here. Project your feelings and beliefs onto others who don't care what you believe or think.

I dont mind that at all, my concern and the sole reason i have posted so strongly this time, i do care that many people who never register here but use the information, are given the correct information. In future i will post back up evidence for quality sources, i wont bother responding to links from random websites or pure speculation.

We will see and I have doubts since you have made similar claims like this before. If what you say is true and fact based nobody will have issues but if what you say is driven by your views and agenda like too many of your posts are with limited or even contradictory supporting evidence you will keep getting what you get here.

 

[large_ghostman]

Cant be bothered to read all that, go start your own thread on this subject, fill it with as much hill billy BS as you want. But dont expect me to read any more of your nonsense ok.

 

[large_ghostman]

Western
https://www.aliexpress.com/item/BFP...0dDLWLn&transAbTest=ae803_1&priceBeautifyAB=0

Danfoss knock off! I am tempted to order one and see how good they are, i found some other knock off pumps in China at silly prices. I purchased a Chinese knock off diaphragm PTFE pump last year, it was a fraction of the normal cost and i didnt expect much from it. Its been outstanding and handled some really harsh substances with no problem.

 

[tcmtech]

Cant be bothered to read all that, go start your own thread on this subject, fill it with as much hill billy BS as you want. But dont expect me to read any more of your nonsense ok.

Wow! You really cant handle having your own game thrown back at you.

Don't start what you cant handle the reality of.

 

[Western]

Western
https://www.aliexpress.com/item/BFP...0dDLWLn&transAbTest=ae803_1&priceBeautifyAB=0

Danfoss knock off! I am tempted to order one and see how good they are, i found some other knock off pumps in China at silly prices. I purchased a Chinese knock off diaphragm PTFE pump last year, it was a fraction of the normal cost and i didnt expect much from it. Its been outstanding and handled some really harsh substances with no problem.

Thanks for that, I'm slowly understanding the whole picture. Can't complain about the price either.

 

[large_ghostman]

Thanks for that, I'm slowly understanding the whole picture. Can't complain about the price either.

I hope to get the mid sized lab centrifuge out tomorrow and spin some old oil for you. This isnt what i use for cleaning, but using it with test tubes and some light should give you an idea of what you take out with spinning.

I dont know how much G force is produced with the oil spinners, so i am making a guess with the lab one, the current rotor holders in it are limited to 6000RPM (roughly 12G i think). I have another carrier thats rated to 9000 RPM but changing the cradle then balancing the rotor is a PITA. The bigger lab centrifuge i have goes way higher, but the G force is way above what a oil spinner can produce, so a bit pointless to use for this. Its got a ultra cooling system and temp control on it.

When using these bigger machines for cell work etc, the friction inside the tubes heats proteins beyond the point the denature, thats why they have special temp control systems. The one i have will spin Ribosomes to the bottom of a tube in 3 mins. I dont know the actual max G force on this one, but i do know it takes some doing to spin down ribosomes, also its the kind of centrifuge with a retarded start on it, this is so you can set it up and get out the room while it spins!!

The pic is damage done by a machine slightly bigger than mine, if my memory is correct the machine was running 3/4 top speed!! Thats why you always make sure the rotor is balanced before turning on. Imagine a tube of 5gram doing all that damage when the balance is off and the rotor gives way!

Actually we are looking at a electronic way to help clean waste oil, a bit like the magnetic carbon except pulsing a coil and charging the soot particles, then using a foil plate to attract the particles (really bad explanation sorry!), if it works then you should et a better burning oil from it.

You got any interest in flu gas treatment? If so i will post up something you find interesting, i wouldnt use the product on edible crops but used on flowers or trees it makes a really decent fert.

 

[large_ghostman]

Western

I was emailed a 2nd year project paper from another student, apparently they found a method of getting most of the black soot out of used oil. Why does this matter? Well soot or the small particles you get cause smoke and alot of the emissions you get when burning the oil.

The project had nothing to do with cleaning waste oil, its actually about light transmission but used oil was one of the test fluids. Looking at the paper its kinda opposite what i would expect, but if its of use to you i will give it try and see what happens. I cant post the entire paper as it was last years project for them, but i could tweak the procedure and if it works outline it. One oddity in it is you need a small amount of walnut shell! yes seriously!

I tried walnut shell for carbon and it was rubbish, but might work for what they did. I have the centrifuge set up so will spin some oil later tonight when everyone out the way, it takes some time to set up level etc as well.

 

[unclejed613]

It depends on what your end intentions are.

I've been putting serious thought into the DIY micro refinery concepts over the last year or two give how much used oil I am collecting now.



For me I certainly see the potential for doing some deeper personal research in the concept myself just to see what comes of it, if anything at all.

I don't know where I may go with it but I have now been pondering on several different micro refinery designs from simple single batch barrel based cookers to substantially more complex continuous flow multi stage processors.

i found this link: https://usfiltermaxx.com/en/content/9-make-black-diesel it's not a long article, but looks like there's a lot of useful information there. the centrifuge in the article reminds me of the old Kenmore upright tub washing machines.

it wasn't mentioned in the article, but if i remember correctly, there's 3 types of crude oil, paraffin base, napthalene base, and asphalt base. i have heard (still not able to find info one way or the other) that mixing motor oils of different bases (primarily the mixture of paraffin and asphaltic oils) creates sludge. however, i have looked at some of the info online, and the differences between the crude oil "bases" are: paraffinic oils contain linear chains of carbon, naptha based oils contain ring chains (of 4 or 5 carbon atoms), and asphaltic oils contain benzene ring molecular chains. since the paraffinic molecules are linear chains, they are better lubricants, and so most motor oils are paraffinic. so, even if such a reaction could happen, the chances of buying motor oil made from naptha and asphaltic based oils are very small, especially in the USA.

 

[large_ghostman]

Benzene is not found in the EU much lubrication wise. Even in uni labs its being phased out in classes. In the EU mixed oils (all oil from garages etc is mixed), if its an agricultural place then you get alot of different oils or oil products. Basically anything used tractors and machinery. If its a car garage then you get brake fluid and coolants as well, if its a main dealer then you risk getting paint shop solvents thrown in the waste barrel.

Doind it small scale is possible, but doing it in a safe and green manner is not easy. That sludge you mention is often used as a binder in power station solid fuel pellets, mainly industrial type ones because they can hit a high enough temperature for the exhaust to meet regulations. The Eu.UK and alot of the common wealth take emissions seriously, even Saudi and India are trying to comply. Ignoring good practice and spewing toxins out is really not clever in the 21st century. There is no need except greed......

 

[large_ghostman]

i found this link: https://usfiltermaxx.com/en/content/9-make-black-diesel it's not a long article, but looks like there's a lot of useful information there. the centrifuge in the article reminds me of the old Kenmore upright tub washing machines.

it wasn't mentioned in the article, but if i remember correctly, there's 3 types of crude oil, paraffin base, napthalene base, and asphalt base. i have heard (still not able to find info one way or the other) that mixing motor oils of different bases (primarily the mixture of paraffin and asphaltic oils) creates sludge. however, i have looked at some of the info online, and the differences between the crude oil "bases" are: paraffinic oils contain linear chains of carbon, naptha based oils contain ring chains (of 4 or 5 carbon atoms), and asphaltic oils contain benzene ring molecular chains. since the paraffinic molecules are linear chains, they are better lubricants, and so most motor oils are paraffinic. so, even if such a reaction could happen, the chances of buying motor oil made from naptha and asphaltic based oils are very small, especially in the USA.

On a technical point naptha based covers a wider margin in the crude oil sense.

No idea if you seen this but its got alot of information, but be a little careful as its way out of date now being from 1995. but alot of it is still relevant
https://www.researchgate.net/profil...e4d8d6496ad6b/Catalytic-Naphtha-Reforming.pdf

 

[large_ghostman]

This one is from tires, but to the best of my knowledge the method at least in the EU has been superseded. I can try and get more uptodate info, but alot of it is behind paid walls, so i cant post full papers just the abstracts and links, i can send you full copies for your own research et as long as it isnt commercial...,Blah Blah Blah normal disclaimer for scientific paper sharing insert here.

https://www.sciencedirect.com/science/article/pii/016523709285014C

This is more upto date but the figures given for arab light crude i have seen disputed in another paper. I think its solely down to the well source its sampled from

https://www.researchgate.net/profil...E-and-Effect-of-High-Reaction-Temperature.pdf

 

[unclejed613]

because a molecule contains a benzene ring, does not make it benzene...

Benzene is not found in the EU much lubrication wise.

of course not, as it's not a linear chain molecule, benzene and other petroleum products from asphaltic crude oil (which all have one or more benzene rings in their molecules) are not very good lubricants. if you know anything about organic chemistry, you know that most organic compounds used in medicine and foodstuffs, as well as most compounds found in nature, all have benzene rings in their molecular structure. this does not mean they ARE benzene, or act chemically like benzene. the benzene ring is a basic building block in organic chemistry.

Ignoring good practice and spewing toxins out is really not clever in the 21st century. There is no need except greed......

actually if a system is spewing out unburned crap, then there is a financial reason to fix it. companies that like to maximize profits are always looking for more efficient ways of using fuel. a power generation system with 25% efficiency means you are buying more fuel, and wasting some of it. so, off the top, if the entropy losses are 25%, and the power output is 25%, that leaves 50% that is escaping as unburned fuel products. company XYZ wants to improve productivity in their factory, so what to do? start chipping away at that 50% figure and transfer the savings to the efficiency side of the equation. add some improvements in the motor, such as advancing the ignition timing, changing valve timings for better performance, better vaporization and aeration of the fuel, etc... add some means of trapping unburned fuel in the exhaust, and recycling it to the fuel supply. if the upgrade is completely effective, there's now 3 times as much energy delivered to the factory, for the same fuel expenditure, as well as the amount of fuel products in the exhaust being vastly reduced. while the environmental problem wasn't considered a main reason for improving the equipment, there is definitely an environmental benefit from the improvements. unfortunately, most environmental regulations do not reward efficiency improvements, but require the plant operator to add all kinds of "stuff" to the engine intakes and exhaust, requires the reduction of fuel usage (by increasing the downtime of the equipment), the keeping of extra written records, etc...


there's a lot of machinery out there that was designed and built during a time when fuel was cheap and plentiful. internal combustion engines at the time, although very inefficient, were an improvement environmentally over other sources of power. what was used for power before that had been steam power, which required huge amounts of wood or coal, and as a result, cities like New York were shrouded in black smoke

 

[large_ghostman]

of course not, as it's not a linear chain molecule, benzene and other petroleum products from asphaltic crude oil

Benzene was used extensively in petrol until ~15 years ago maybe longer. I have a Gas chromotagraph taken from some very old petrol that shows one the main peaks is benzene.

if you know anything about organic chemistry,

Not my strongest subject, but i am taking it as a sub course for my Masters Degree to try and increase my organic chem knowledge. But i would sayi am far from being a organic chemistry noob.

the benzene ring is a basic building block in organic chemistry.

More of a nit pick but today more relevant, benzene was once more important than it is now, thats one reason it has a special symbol, however every organic chemistry from 1800 to present day will tell you Carbon is the main building block, in fact ORGANIC means Of Carbon base. So Organic chemistry is the study of Carbon based chemistry.

Not being funny with you, but i think it matters.

actually if a system is spewing out unburned crap

Now here is the biggest difference between America and much of the rest of the world, this is where most of the trouble starts. To Americans if its burning correctly then its ok, much of the rest of the world is different, even with full combustion we have tight rgs on what can and cant be expelled, not all hydrocarbons break down into CO2 and H2O on full combustion. Many spew out other compounds, especially waste oils from garages. This is where we will always differ, I am in favour on restriction on what is sent into the atmosphere, even CO2 to some extent as its useful and an easy capture.

I posted you a scientific document, i did so in good faith because your initial post had some ring errors in, so rather than say anything i posted you some information.

Deleted derogatory comments about another member - Moderator

Sorry but i dont get why you would think it necessary having made technical errors to then go on about the financial side.

Lets Stick to the actual chemistry of it, Without trying to sound Arrogant, i think doing a masters degree in environmental engineering, a course designed to create engineers of the future to make cleaner fuels and systems etc, would be more than enough for us to lecture each other at the noob level.

while the environmental problem wasn't considered a main reason for improving the equipment,

Again i think thats a purely a difference in where we are from, in the EU and UK, things like EGR were brought in purely to reach emissions targets. A good example of this difference has been fairly recent.

The EU and many other countries are purely emission target lead, thy signed up for this and that agreement for emissions. Then had to hit the targets, this is why we had the VW problem/scandal. Few of the changes now made to engines are anything but emission lead here. The EGR was done solely to lower emissions from diesel engines.

A huge chunk of the world is committed to getting rid on the internal combustion engine, by 2040 i think (which is in my life time). Not that I agree with this, my own view is they missed the point and took a wrong turn. I think fossil fuels are a bad idea in internal combustion engines, we dont need them. There are many fuels that burn cleaner and better (especially diesel based engines), many of them cheaper than oil.

My own view is keep oil for what we really cant do without it for, and use other/better fuels for transport etc. One other indicator of us being emission lead is the new car racing formula. Traditionally most advances in cars have come from the racing track, look at F1 as an example.

F1 cars were where anti locks brakes were first developed and used, same with traction control and many other systems, even regen braking. So you could look each season and spot the latest addon, this would tell you roughly what the latest cars in 3-4 years time would have on them.
Whats interesting is the newest formula here is electric car racing, and most the top brand car manufactures are taking part. I dont know what else to say except like it or not electric cars are the future here (personally i dont like it, but that my view).

So its really hard to discuss much but chemistry with you, the reasons you give for things like EGR systems, are certainly not why they were developed here, as most dont enhance the power and it was made perfectly clear why they were brought in, that dosnt mean it dosnt hold true for where you are (except i would dispute the power figures for EGR systems), but America isnt the world. Most of the world is following the Paris and other agreements America never signed too (well ok they did sort of with paris. So its very difficult to transfer systems.

This is one reason i started this thread, it was for someone in Australia.

Deleted derogatory comments about another member - Moderator

as our countries have the same kind of emission rules, i based my post on those. Had the guy been from America i would have stayed out the thread.

We dont even use the same types of petrol or fuel mixes. You have ethanol and methanol based petrol, here its very hard to find, so when telling people whats in waste oil, pleas make it clear the country your talking for, as it seems very very different to what we get in waste oils, the danger is unless we make that clear, then people from other countries end up with information not relevant for them.

Regards
LG

 

[tcmtech]

Deleted responses to derogatory comments above - Moderator

 

[large_ghostman]

Jed i think we should find a way to work together, it wont be easy as we are on opposite sides of the world, our entire systems are different, So my suggestion is we try and find common ground, then as long as we are clear where the rules applies and which country we are basing our info on, i think it would help alot of people. Arguing over some things is not helpful, i will give you an example of what i mean.

Here we call the back storage bit of a car a 'boot' you call it a 'trunk'. Me and you arguing over what its called it so pointless because actually we are both right, just in different places. So if you can see my logic, i am suggesting we team up and use that as an advantage, that way those with 'boots' get info and those with 'trunks' get info.

I will always side with the clean environment side, my thinking is i dont take a number 2 in my living room. Equally i try not to do the same things with the environment. We may have opposing views on this, i dont know, if we do then its a simple case we lay the facts and agree to disagree.

Technical issues may crop up due to location, so calmly we will work through those. We will get one of two out comes, one person will be right and the other wrong (in which case we gracefully concede ) or we are both right for our location.

Also i will respect the threads you start and i would like the same in return.

I hope this has all made sense, the other option is hit the ignore key, i suggest this everyone else with problems with people. why are we so reluctant to use it?? I think we should all reflect on that. A perma ban was handed out, i am sure some/many are happy with this, but i had a couple of days thinking time.

All of us so called caring members could have solved this ourselves,if we had pushed the ignore button they vanish. if enough people use it in the right way, then i see little need for bans. Also it makes it much easier for mods to post where the real trouble is, if they choose to do nothing then maybe they should do some thinking, but my point is us as members have alot of power we dont use.

That ignore button is pretty powerful if enough people use it, i know the common saying is 'dont feed the trolls' and i hate that saying, but effectively thats the ignore button. when enough people simply press that then the 'troll' (again we need to find a better word) gets frustrated and bored, they go away or they ramp it up, we wont see them ramping it up so it dosnt matter to us, but they stick out like sore thumbs to the mod team. So we also help them.

I do hope i have made sense!

I got alot going on, some stuff has come up i have to deal with, so i will be in and out the forum for a little bit

 

[unclejed613]

there are going to be things we disagree on, that's human nature plain and simple. there are things our respective governments disagree on, and that's what makes our countries different. if somebody told me 20 years ago that your country was trying to ban "pointy knives" using those exact words, i would have thought it was a Monty Python sketch. your country was one of the greatest driving forces behind the Industrial Revolution. tinkering, engineering, and inventing was a more common pastime than playing Cricket. unfortunately, as i've mentioned elsewhere, it seems that today you are restricted from tinkering with anything more harmful than bubble wrap, and that's a very sad state to be in. if people in a society are restricted from inventing new technologies, and improving the state of the art, they will either stop inventing, or take their inventions elsewhere. when such restrictive policies are accepted and bought into by a populace, they have lost something very important, and that's the freedom to create technology. when the Industrial Revolution began, human slavery was commonplace. the Industrial Revolution made slavery obsolete. when one machine in one hour can do the work of 1,000 men working for a week, then there's no longer any excuse for slavery. there are, however people who would prefer that we reverse the Industrial Revolution. their belief is that technology has somehow corrupted humanity, and will destroy the environment, and it would be better if we went back to a Bronze Age lifestyle. it sounds like such a simple life that everybody could enjoy... except, without industrial technology, you will again need slaves to build that bridge across the river, or to build that new road from this town to the next one....

so, i'm not trying to troll you. i have some serious differences of opinion with "modern luddites" who try to turn back the clock by legislating crippling restrictions on technology. when these luddites get traction by becoming bureaucrats and convince the public that they "know what's best for everybody" then our society is in a precarious position. and that position becomes more dangerous when tinkering and innovation are stifled, because it means we might not get a next generation of engineers and scientists who can maintain the present state of the art, let alone advancing it.

 

[large_ghostman]

it seems that today you are restricted from tinkering with anything more harmful than bubble wrap,

I have said before your misguided on us being allowed to play with plastics!! let one as dangerous as suffocating and noisy as bubble wrap!

I cat argue with much of the rest, except to say dont underestimate some of us younger people. We are aware of what is going on, you would be surprised how much 'real' science is going on here and there. more than one way to skin a cat, but general rule of thumb is to skin them out the sunlight and somewhere people of a nervous nature wont get upset by the sight..........

Your take on the industrial revolution does have alot of resonance amongst many of us currently at uni, we are becoming restricted in the solvents we can use. Its not uncommon for a undergraduate lab to contain little more than ethyl acetate, anything else involves many questions and much paper work. If you ever feel too happy and would like a little depression, take a look at one of our greatest ever chemistry university websites (Nottingham), i dont go there myself but look at the new 'green' chemistry building and the blurb on it.

Some of the concept is great, however the boasts on solvent choices etc are a good indication of where we are at. Just as a side note, a few weeks ago we got informed about the ultra low freezers (-78c). ALL undergraduates are no longer allowed to directly access them, they have to use a standard -20C one, from there a tech moves things to the ultra cold one.

Although my course is technically a post grad course, i am however also technically an undergraduate. so for me it just depends on the day and who is in the freezer room. But even grads have had to have mandatory training to use them.

The other side of the coin.... Without the restrictions, fewer of us would actually make Chloroform etc. So for some people the restrictions have given us a greater level of hands on experience. Normally conducted in a similar fashion to cat skinning