# Backflushing: Why?



## Blue_Cafe (Jun 22, 2020)

Why is backflushing a thing?

By reversing flow through the grouphead with a backflush, you are pushing all the stuff you are trying to clean from the grouphead back into the boiler and through the 3 way valves.

It is effectively pushing the crud back into the system, not getting rid of it.

If you look at the design of most of the espresso boilers, they are not bottom outlet. They have a weir pipe in them, this means that the crud you are pushing back in to the boiler can't get back out and silts up on the bottom.

Any crud not caught in the wier, gets pushed into the valving.

I don't get it. surely for cleaning you flush out, not in?

I read Gaggia do not recommend back flushing. After looking at this, i would have to agree.

A cleaning cycle with solution and a periodic removal and clean of the shower head seems much more "Correct".

The process plumbing and flow of a espresso machine is simple enough and i am struggling to see what the backflush is supposed to do?


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## Blue_Cafe (Jun 22, 2020)

I'm not the only one it seems.....


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## Blue_Cafe (Jun 22, 2020)

Whodathunkit...


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## ChilledMatt (May 9, 2015)

On the pre 2015 model water does not go back to the boiler when backflushing. If it did whenever your machine choked coffee would end up in the boiler. Strangely one of the biggest Gaggia outlets and web resources surrounding Gaggia Classics in the US do recommend backflush as part of routine maintenance. I believe it is because the US didn't have the inferior 2015 machine foisted upon them as we did in Europe. I think Gaggia UK are safeguarding against users backflushing the wrong Classics. I did have a 2015 Classic years ago for a short while, but can't comment on whether backflushing is good or bad for that model.

https://wiki.wholelattelove.com/Gaggia_Classic/cleaning_and_maintenance

I have opened up several pre 2015 Gaggia Classics and I am yet to find coffee in the boiler. Solenoid valves if not decreased will get gunked up with coffee oils. The most efficient way to clean them is a periodic backflush with a suitable detergent. I believe WLL demonstrate how to do this safely.

Sent from my SM-A705FN using Tapatalk


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## Blue_Cafe (Jun 22, 2020)

ChilledMatt said:


> On the pre 2015 model water does not go back to the boiler when backflushing. If it did whenever your machine choked coffee would end up in the boiler. Strangely one of the biggest Gaggia outlets and web resources surrounding Gaggia Classics in the US do recommend backflush as part of routine maintenance. I believe it is because the US didn't have the inferior 2015 machine foisted upon them as we did in Europe. I think Gaggia UK are safeguarding against users backflushing the wrong Classics. I did have a 2015 Classic years ago for a short while, but can't comment on whether backflushing is good or bad for that model.
> 
> https://wiki.wholelattelove.com/Gaggia_Classic/cleaning_and_maintenance
> 
> ...


 Well, lets believe somebody who flogs bits and bobs over those who make, service and design them eh....

Get yer pencil and paper out and draw the line of flow from the pump to the puck.

a "backflush" in the Gaggia world is simply the act of running a shot against a dead head (Blanking plate).

So when you press the brew button, the flow line is open, all the way from the water bucket, through the pump, through the safety valve, through the expansion valve, through the boiler, through the group head and to the Portafilter. If you (as you insist above) don't believe that to be the case, please explain what magic and woo gets the water into the blanking plate (and by some other magic, back through the group head and through the shut expansion valve).

So, we establish the pathways are open from the portafilter BACK to the boiler.

Well, now go and get some of this cleaning powder or tablets you "backflush" with.

Here is a good example of what happens when descaler meets dirty machines:






It fizzes up. So what does that mean in the gaggia with its arse end blocked off?

Well, that fizz goes up not down, up the group head, up the ginnels, past the expansion valve, into the boiler.....

And you've the other problems of depressurising solution blasting its way through the unit when you turn it off but apparently the expansion valve is this zero static device which acts instantaneously.

Gaggia techs tell you that they see boilers are damaged by "Backflushing". Why ignore them?

Edit: And its not "Coffee in the boiler" thats the issue, The Aluminium boiler has a passive layer which protects the boiler from corrosion and pitting.

It only takes a few molecules (yes, that small) of certain compounds and elements to penetrate this passive layer and begin the process of pitting and corrosion. Look at some pictures of old Gaggia boilers and the pitting they have. Its my bet this is caused by backflushing cleaning agents back into the boiler void and probably why Gaggia don't recommend it.


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## DavecUK (Aug 6, 2013)

@Blue_Cafe* Please, please stop,* you are only serving to confuse anyone that's reading all this. Especially true as this is in technical faults general area and not even confined to Gaggia machines area, even then it wouldn't be right..

If you have an E61 mechanical group or *ANY* machine with a solenoid valve *you must backflush it with cleaner from time to time dependent on usage. *More regularly with a solenoid group, if you don't you WILL get problems.

If you don't know whether it has a solenoid valve, rule of thumb:* if it discharges dirty coffee water back into the drip tray by any route other than the portafilter, you must backflush it with cleaner from time to time* dependent on usage

Machines with what they call *a brew valve*, there is *no point backflushing*. You can tell if you have a brew valve, put a portafilter with a blanking disk in, run a shot, then end the shot, you won't hear anything venting out....be careful and unlock the portafilter.

Brew valves are the cheapest and most horrible way of an espresso machine working, they open at pressures above 5 bar and allow flow (spring and ball seat mechanism inside them), when you stop the shot, the pressure simply dissipates through the puck. If you get a choker, then you get a portafilter sneeze if you remove the portafilter without waiting a minute or two. Because of this, although backflushing won't hurt them...it's a bit dangerous for you and does not good at all because it can't clean anything worth cleaning.

I'm seriously considering asking the mods to remove your posts about this....but hopefully people will read what I've written.


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## Blue_Cafe (Jun 22, 2020)

Edit:

Bold letters huh. That will tell me, much the same as changing your avatar in mockery proves you right, or a page long validatory diatribe into your decades of work at the coal face with manufacturers...

You are so intent on insisting i don't know what i a talking about (probably because i have dared to question your immense knowledge) that you haven't actually really read or understood my points.

How about this: A solenoid valve does not make an machine a E61 system.

If you think it does (and you clearly do) then you need to have a bit of a think about it.

I won't apologise for my grammar if you find fault in that again, i can't help my dyslexia lol.


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## DavecUK (Aug 6, 2013)

I've mentioned this post to a moderator because quite frankly I don't care how you see me personally, or whether you believe me. I don't want to see people have problems because they followed your advice. I don't know what more I can do but I do think there is a level of misinformation that can be damaging. you are not asking to learn, you are making statements and then dismissing what others say sometimes because



> Well, lets believe somebody who flogs bits and bobs over those who make, service and design them eh....


 Unbelievable.


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## Blue_Cafe (Jun 22, 2020)

DavecUK said:


> I've mentioned this post to a moderator because quite frankly I don't care how you see me personally, or whether you believe me. I don't want to see people have problems because they followed your advice. I don't know what more I can do but I do think there is a level of misinformation that can be damaging.


 Good lad, just like Mr Shades, if you can't stop somebody from saying what you disagree with, get them banned lol.

People have problems because i am telling them not to backflush a Gaggia? The same Gaggia classic that Gaggia themselves tell its users not to backflush because it damages them?

The same Gaggia classic that Gaggia themselves tell you backflushing damages the boiler?

The same Gaggia classic that Gaggia themselves tell its users (actually enforced this by locking it out) NOT to mess with the safety valves because it damages the machines?

You are championing this unrecommended and destructive practices and swishing your CV around as validation, yet when challenged, you can't do much more than get that user shut up or banned?

Think about that for a minute. You and Mr shades have mocked me, insulted me, called for me to be silenced, called for me to be banned, because i agree with the manufacturers of a machine that practices you encourage are dangerous and damaging and yet its me that that's being the dangerous and damaging one?

Lol.


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## DavecUK (Aug 6, 2013)

*I'm not asking for you to be banned*, I wouldn't do that. However, I do think there needs to be some level of* self control* when making such definite statements that could cause people to follow your (bad) advice. You are also not reading properly what others are writing. If you don't have that self control then I don't know what they should do...perhaps just ask you to cool it a bit with the technical advice that's framed as a question....then argue with misplaced confidence all the answers you get.

Experienced members know to ignore you, new inexperienced members won't, don't you realise that.


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## Pablo El Beano (Jun 15, 2019)

Blue_Cafe said:


> Good lad, just like Mr Shades, if you can't stop somebody from saying what you disagree with, get them banned lol.
> 
> People have problems because i am telling them not to backflush a Gaggia? The same Gaggia classic that Gaggia themselves tell its users not to backflush because it damages them?
> 
> ...


 You are coming across as a bit of a dick mate. Calm the fuck down. Nobody cares what you think now. You've shown everyone what you are.


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## Bolta (May 11, 2014)

If you place an aeropress filter paper on top of the puck only clean water is vented through the 3-way valve and avoid the need for detergent flushes.


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## BlackCatCoffee (Apr 11, 2017)

I do not understand why in the above video they suggest you do not backflush the new models that are equipped with a solenoid. Gaggia do in the manual tell you to clean it using their cleaning tablets that are designed to be used for backflushing. All seems a bit mixed message to me. I do not understand how you are able to maintain a solenoid equipped machine by not doing it.

As far as commercial machines, E61 equipped machines and other prosumer models go I have not personally heard a single manufacturer advise against back flushing and I can also say I have never found coffee silt in a boiler I have drained.

If I owned a pre 2015 or a new Classic Pro I would absolutely backflush.


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## Blue_Cafe (Jun 22, 2020)

Anyone else want a pop? lol.

Things get quite nasty when you row against the flow huh.

I am happy with what i have said on these matters. Feel free to prove me wrong with logic and reason.

If all you have is insult and mockery, your arguments are worthless.

Carry on.


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## DavecUK (Aug 6, 2013)

DavecUK said:


> @Blue_Cafe* Please, please stop,* you are only serving to confuse anyone that's reading all this. Especially true as this is in technical faults general area and not even confined to Gaggia machines area, even then it wouldn't be right..
> 
> If you have an E61 mechanical group or *ANY* machine with a solenoid valve *you must backflush it with cleaner from time to time dependent on usage. *More regularly with a solenoid group, if you don't you WILL get problems.
> 
> ...


 I'll just re-quote this so it doesn't get buried


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## Blue_Cafe (Jun 22, 2020)

BlackCatCoffee said:


> I do not understand why in the above video they suggest you do not backflush the new models that are equipped with a solenoid. Gaggia do in the manual tell you to clean it using their cleaning tablets that are designed to be used for backflushing. All seems a bit mixed message to me. I do not understand how you are able to maintain a solenoid equipped machine by not doing it.
> 
> As far as commercial machines, E61 equipped machines and other prosumer models go I have not personally heard a single manufacturer advise against back flushing and I can also say I have never found coffee silt in a boiler I have drained.
> 
> If I owned a pre 2015 or a new Classic Pro I would absolutely backflush.


 Because there is no such thing as a "Backflush" in a Gaggia, There is no flow. Just the expansion of water away from the portafilter.

The tablets are not designed for backflushing either, They just fizz up and clean the shower screen and holder of oils migrated back from the puck. "Flow" isn't happening.

If you pressurise the system with the blanking disk in, the expansion of water which has all the crud of the cleaning of the shower screen etc just moves back up the system.


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## Blue_Cafe (Jun 22, 2020)

DavecUK said:


> I'll just re-quote this so it doesn't get buried


 Stop spamming the thread


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## BlackCatCoffee (Apr 11, 2017)

Blue_Cafe said:


> Because there is no such thing as a "Backflush" in a Gaggia, There is no flow. Just the expansion of water away from the portafilter.
> 
> The tablets are not designed for backflushing either, They just fizz up and clean the shower screen and holder of oils migrated back from the puck. "Flow" isn't happening.
> 
> If you pressurise the system with the blanking disk in, the expansion of water which has all the crud of the cleaning of the shower screen etc just moves back up the system.


 Well I am not 100% familiar with the new design of the new Classic Pro however I do not see why it would be any different to any other machine with a 3 way solenoid valve and I do not know what you mean by "There is no flow. Just the expansion of water away from the portafilter".

I do not want to get in to an argument about it but I can tell you that the tablets they advise you to clean with are the same ones they supply with the commercial machines for backflushing.


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## Blue_Cafe (Jun 22, 2020)

Bolta said:


> If you place an aeropress filter paper on top of the puck only clean water is vented through the 3-way valve and avoid the need for detergent flushes.


 Good idea, except i think the system is designed such that the water on/in/from the puck is not of sufficient quantity that it makes it back through the expansion valve.

Think of it this way, the flow through the expansion valve only comes from the decompression of the compressed fluid/gas, etc in the portafilter. If you watch the vent pipe during release, the actual volume of fluid is small. If you were to calculate the free volume from the three way valve to the group head outlet, i would bet that it is greater than the volume of water expanded back during release.

So, what that means then in normal operation, its not the puck dirt which is getting the valve in trouble, its the scale from the boiler.

However, by putting effervescent chemicals in the portafilter and then pressurising against a dead head and also opening up the boiler space to the dead head and its dirty, fizzing contents, you begin to push that crud back up the system. Most back flushing videos tell you to cycle until you see this crud coming out of the exhaust pipe which means that the above premise that there volume on decompression is normally small (hence you need to keep repeating this).

Also, you have just pushed all that crud through the expansion valve. on shut down. Exactly what you didn't want to be doing in the 1st place


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## Blue_Cafe (Jun 22, 2020)

BlackCatCoffee said:


> Well I am not 100% familiar with the new design of the new Classic Pro however I do not see why it would be any different to any other machine with a 3 way solenoid valve and I do not know what you mean by "There is no flow. Just the expansion of water away from the portafilter".
> 
> I do not want to get in to an argument about it but I can tell you that the tablets they advise you to clean with are the same ones they supply with the commercial machines for backflushing.


 I don't want an argument either _

When you backflush a Gaggia, you put in a blanking plate. This dead ends the system. There is nowhere for the water to flow, It is akin to trying to pump up an already full vessel. Nothing happens flow wise. Your pump just dead heads after compressing any dissolved gasses etc remaining in the boiler void or water (Fluid is incompressible).

However, on pump shut down, the overpressured system, along with the seals, boiler space, pipes, tubes, dissolved gases etc relax and expand (against the blanking plate) and go to the point of least resistance. This hopefully is the vent port, but can be anywhere in the system whilst the expansion valve is closing.

Watch the video above. All that crud in the blanking plate has now been expanded back through the system into the vent.

Its doing more harm than good.


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## davril (Sep 17, 2012)

Blue_Cafe said:


> Good idea, except i think the system is designed such that the water on/in/from the puck is not of sufficient quantity that it makes it back through the expansion valve.
> 
> Think of it this way, the flow through the expansion valve only comes from the decompression of the compressed fluid/gas, etc in the portafilter. If you watch the vent pipe during release, the actual volume of fluid is small. If you were to calculate the free volume from the three way valve to the group head outlet, i would bet that it is greater than the volume of water expanded back during release.
> 
> ...


 I am sure you have the best intentions trying to help people but you are totally and utterly confused about how espresso machines work and you clearly do not understand the job of the expansion valve or solenoid.

Please stop.


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## Blue_Cafe (Jun 22, 2020)

davril said:


> I am sure you have the best intentions trying to help people but you are totally and utterly confused about how espresso machines work and you clearly do not understand the job of the expansion valve or solenoid.
> 
> Please stop.


 (Actually, its the solenoid which drives the expansion valve.)

Which bit is wrong then?


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## Drewster (Dec 1, 2013)

Blue_Cafe said:


> (Fluid is incompressible)


 This thread has been interesting in a "watching a car crash" sort of way...

I must be honest and admit I really can't be bothered to read it all.... but....

I find it really undermines peoples arguments when they post absolute bollix when attempting to sound "scientific".....

The word "fluid" is NOT interchangeable with "liquid".....

Both liquids and gasses are fluids....

Gases absolutely ARE compressible (otherwise Calor Gas bottles would be pretty big)

Therefore fluids ARE compressible

(I think technically liquids might even be compressible to a certain extent?
I might have done some study on incompressible fluids but it was many years ago.
I think liquids might be considered incompressible for practical purposes....)


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## Blue_Cafe (Jun 22, 2020)

It's hydraulics.

Fluids (not gas) is for most definitions incompressible,

Gas certainly is compressible

Yes, the specific term is Liquid vs Gas but this is a coffee forum not science class and i think it's clear what the meaning is.

And yes its a car crash lol,

I await some reasoned counter argument against my thoughts. "you are talking out of your arse" isn't going to cut it


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## 2cups (May 6, 2019)

As they say, a little knowledge is a dangerous thing...


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## MediumRoastSteam (Jul 7, 2015)

One of the dangers of the internet. There's a lot of misinformation out there, including this forum. Digest information, filter the hell out of it, apply your own common sense and research factual and trustful information. Always question yourself.

detergent WILL NOT GO back into the boiler on a Gaggia equipped with a 3 way solenoid valve. You can test that yourself. Do the back flushing. Remove the portafilter. Draw water from the group. Water is clean.

Some say Father Christmas exist. It's up to you to believe in it.

This OP is nonsense.

Over and out.


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## Blue_Cafe (Jun 22, 2020)

MediumRoastSteam said:


> One of the dangers of the internet. There's a lot of misinformation out there, including this forum. Digest information, filter the hell out of it, apply your own common sense and research factual and trustful information. Always question yourself.
> 
> detergent WILL NOT GO back into the boiler on a Gaggia equipped with a 3 way solenoid valve. You can test that yourself. Do the back flushing. Remove the portafilter. Draw water from the group. Water is clean.
> 
> ...


 So why do Gaggia say that this practice damages their boilers?

Are they lying?


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## MediumRoastSteam (Jul 7, 2015)

Blue_Cafe said:


> So why do Gaggia say that this practice damages their boilers?
> 
> Are they lying?


 Try it. Prove it. I had one for years (2011, 3 way). It does not go back to the boiler!

edit: otherwise coffee will go back to the boiler too! It's nonsense!


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## Pablo El Beano (Jun 15, 2019)

I can't believe people are still engaging with this idiot. He's havin' a laff.


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## Drewster (Dec 1, 2013)

Blue_Cafe said:


> It's hydraulics.
> 
> Fluids (not gas) is for most definitions incompressible,
> 
> ...


 I refer the Honourable Gentleman to my previous reply..



Drewster said:


> The word "fluid" is NOT interchangeable with "liquid".....
> 
> Both liquids and gasses are fluids....
> 
> ...


 Therefore the statement:

*Liquids* *are* for most definitions incompressible

Would be accurate.
(Note I pedantically corrected is to are in addition to Fluids to Liquids)


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## Blue_Cafe (Jun 22, 2020)

MediumRoastSteam said:


> Try it. Prove it. I had one for years (2011, 3 way). It does not go back to the boiler!


 Righto, so your only argument against my support of Gaggia's insistence that backflushing is bad practice is that yours is ok?

:classic_huh:


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## Blue_Cafe (Jun 22, 2020)

Pablo El Beano said:


> I can't believe people are still engaging with this idiot. He's havin' a laff.


 Try reasoned debate instead of insults and ridicule.

Or have you no thoughts of your own on this?


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## Pablo El Beano (Jun 15, 2019)

Blue_Cafe said:


> Try reasoned debate instead of insults and ridicule.
> 
> Or have you no thoughts of your own on this?


 I've told you my thoughts. They haven't changed. And nor has my 18 months of back flushing my Classic. I love it! Keeps it in tip top shape! There's a word for people like you. I can't quite think of it right now though....


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## Rhys (Dec 21, 2014)

At normal atmospheric pressure liquids used in hydraulics aren't compressible. All matter is compressible though if enough force is exerted (hence black holes exist, which would happen to the earth if it were to be compressed to the size of a golf ball..) but that's beside the point.

I've no idea where you are getting your information from, but when you are digging yourself into a hole, the best advice is to stop digging..

It maybe possible on the new mechanical Gaggia Classics that don't have the metal tube going into the drip tray, but every other (older) Gaggia Classic can and should be backflushed as a weekly routine.









This is the shite that get dispensed from the group. Backflushing cleans all this out. Yes, this isn't a Gaggia, but it works in exactly the same way.

The Gaggia Classic has always been the most affordable way to get a machine that can be backflushed like the bigger, more expensive machines. Now you tell me otherwise and back up your reasons with evidence on why you shouldn't backflush ANY Gaggia Classic. @gaggiamanualservice.com please add your input into this.


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## Blue_Cafe (Jun 22, 2020)

Rhys said:


> At normal atmospheric pressure liquids used in hydraulics aren't compressible. All matter is compressible though if enough force is exerted (hence black holes exist, which would happen to the earth if it were to be compressed to the size of a golf ball..) but that's beside the point.
> 
> I've no idea where you are getting your information from, but when you are digging yourself into a hole, the best advice is to stop digging..
> 
> ...


 As per that bloke who keeps changing his avatar in mockery, you are confusing an E61 machine and its machinations for the pumped hot water kettle AKA Gaggia classic.

I am glad you posted that picture, that's the crap you are pushing through the expansion valve in these classics and you think this is good and then wonder why the valves are so susceptible to damage and blockage.

Try this. Get a pencil and paper.

Draw out the PFD for the E61 and for the Gaggia classic, Draw out the flow paths and gating, valving etc, for both and then see why it is that

A) its not the same

B) its not a good idea.

I've explained very clearly in my posts the logic. Up to now, all i have had is Big bold letters,, Threats to the mods, insults and off track photos.

Take my posts and disect them on logic and fact, one by one. Lets see where we end up.

And lets leave out the insults and the derping and all that bollox and discuss like grown adults huh.


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## Rhys (Dec 21, 2014)

Slayer isn't an E-61..


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## DavecUK (Aug 6, 2013)

I know I shouldn't post this but I can't resist....sorry!


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## 2cups (May 6, 2019)

I think this forum is getting trolled, quite successfully.


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## MrShades (Jul 29, 2009)

Yeah, stop feeding the troll - his posts just aren't worth responding to - but this whole thread just needs removing, as it's downright misinformation and potentially harmful (to machines). I'm entirely with @DavecUK


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## The Systemic Kid (Nov 23, 2012)

OK. Thread is flushed. Time to lock it.


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