PEI Cleaning and Temperature  

Re: PEI Cleaning and Temperature

try not to overthink it, just scuff it up with scotchbrite or sandpaper, wipe with acetone and/or ipa.

adhesion should not be a problem on pei, period. no need to fuss with temperature.

Re: PEI Cleaning and Temperature

I can't say I've experienced the magical adhesion properties of PEI over the past few months with my MK3. 🙂 I've spent most of the time figuring out bed leveling, live Z, pinda temps, etc. all to try to get good consistent adhesion

I've tried the sanding/scotchbrite approach on one side of the sheet. It made a difference but not all the time. I get these periods of time when nothing will stick no matter what I do... IPA, Windex, Acetone, sanding, etc. I'll generally finally resolve it by washing the plate with soap and that makes the most difference for me. But what I realize is that as I'm experimenting with trying to get adhesion back I'm generally doing this on a warm (60C) plate with back to back first layer test prints and IPA on the hot bed seems to make things worse. I suspect it's spreading the residues/oils around rather than removing them.

It might have to do with other environmental factors, etc. but trying to figure out if temperature is one factor to consider here.

Re: PEI Cleaning and Temperature

another factor, is where you put the cleaner. I find it more effective to put the cleaner on the heatbed surface, rather than whetting a paper towel with it, as most of the solvent seems to stay on the paper, rather than doing the proper job...

I usually take the print surface off the heatbed when cleaning, this permits the heatbed to heat up, whilst I clean the cold, or cooling buildplate

regards Joan

Re: PEI Cleaning and Temperature

Yes, I've been keeping an eye on this a bit closer the last few days. It does seem much more effective to 'puddle' the IPA on the bed and spread it rather than to soak it into the paper towel.

In general it seems like the IPA needs to be given time to act on the residue/oils on the bed. If I have the bed above 30C it'll have evaporated almost completely by the time I've spread it all around the plate. If on the other hand I have it at around 27C, then I can spread a good layer around and it'll take 15-20s before it has evaporated. That's when I see things stick much better. So I'm thinking there is some minimum 'soak' time needed to really clean.

Also, yes, removing the plate helps to cool it down while keeping everything pre-heated. I'm starting to do that now. I was trying not to do that too much as I sometimes inadvertently introduce filament dust/blobs on the bottom of the plate which messes around with the leveling, and I also tend to touch it more (at the edges) and was noticing the IPA spreading that around when I cleaned the plate at higher temps. Now I try to clean the edges separately too just in case.

Thanks for the pointers.

RE: PEI Cleaning and Temperature

@andrea-r6

Thanks - PLA sticks again after 2 days of frustration.  Washed PEI steel plate with dish soap and water using scotch brite, puddled IPA on plate and cleaned with paper towel, PLA now prints like new.

RE: PEI Cleaning and Temperature

Ignore ANY suggestion you need to sand the bed; that is downright foolish when soap and water works very well to keep parts adhering to the PEI.

And unless you are wearing gloves, alcohol after soap and water just adds oil (by taking it off your fingers as you wipe it around). So soap and water is the last step.

Hot Water wash: often, as needed, and after any of the following
              (not recommended for daily use on Powder Coated sheets)

• Handle the bed only by the edges.
• Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.).
• Rinse well in hot water - if you have very soft water, rinse a bit longer.
• Dry the bed with a fresh paper towel.
• Handle the bed only by the edges.
• Place bed on printer.

Alcohol wash: every few prints as needed

• Gloves recommended.
• Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils well.
• Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

Acetone wash: infrequent as needed
              (Not recommended for USE on Powder Coated sheets, but some find it necessary)

• Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.

Streak test: when contamination is suspected

• With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates from the bed. If you see any streaks, the bed is dirty and needs a wash.

RE: PEI Cleaning and Temperature

Very similar to what I do.  I would like to a user produced definitive guide to cleaning.  

RE: PEI Cleaning and Temperature

Sounds like a lot of people are spraying IPA onto the surface and allowing it to evaporate, the problem is, the oils are still left behind!.

IPA is good at dissolving the oils, but it then needs to be removed with a paper towel, sucking up the IPA along with the dissolved oils.

Washing up liquid and water is also good at dissolving oils, it's just that it does not dry as fast and is displaced with fresh clean water washing the oils away with the washing up liquid water mix.

Where I used to work, we had in effect a solvent wash machine for cleaning parts which sprayed solvent at the parts, allowing it to run off taking all the grease and contaminants with it, we were then not allowed to touch the parts with our fingers so as not to contaminate them. Fingers really are oily at a microscopic level and we ooze fresh oil out of our pores all the time else our skin will just dry out and crack.

The solvent could be reused a number of times before it had to be distilled to get 100% pure solvent back and leave the oily residue and other contaminants behind, but I think that may be going over the top for home 3d printing, although a sealed container just big enough to submerge a print plate?, the IPA might last longer than you think.

(Smokers - Please don't try this at home, or anybody else for that matter without taking suitable precautions. IPA is highly flammable, and the vapours can knock you out and spread, also it's not good for animals or humans for that matter if ingested.)

RE: PEI Cleaning and Temperature

Posted by: @chocki

Sounds like a lot of people are spraying IPA onto the surface and allowing it to evaporate, the problem is, the oils are still left behind!.

IPA is good at dissolving the oils, but it then needs to be removed with a paper towel, sucking up the IPA along with the dissolved oils.

Washing up liquid and water is also good at dissolving oils, it's just that it does not dry as fast and is displaced with fresh clean water washing the oils away with the washing up liquid water mix.

Where I used to work, we had in effect a solvent wash machine for cleaning parts which sprayed solvent at the parts, allowing it to run off taking all the grease and contaminants with it, we were then not allowed to touch the parts with our fingers so as not to contaminate them. Fingers really are oily at a microscopic level and we ooze fresh oil out of our pores all the time else our skin will just dry out and crack.

The solvent could be reused a number of times before it had to be distilled to get 100% pure solvent back and leave the oily residue and other contaminants behind, but I think that may be going over the top for home 3d printing, although a sealed container just big enough to submerge a print plate?, the IPA might last longer than you think.

(Smokers - Please don't try this at home, or anybody else for that matter without taking suitable precautions. IPA is highly flammable, and the vapours can knock you out and spread, also it's not good for animals or humans for that matter if ingested.)

Good points.

RE: PEI Cleaning and Temperature

The key here is volume; and that PLA is organic based (a material made from plants) and alcohol does a poor job dissolving the sugars released during printing.  Also, it dissolves oils into solution, which means oils remain when you wipe it away. You still leave a film on the plate, no matter how you wipe it off.  The only way to reduce the film is with dilution, and that takes volume.  And that is why running water at a sink works best. 

Do the simple math: a 50 ug finger print, using 5000 ul (5 ml) of alcohol (a lot to pour on to a flat bed): is still 1/100 oil in solution. Using 50 ml (1/10th a bottle) reduces it to 1/1000, or 1000 ppm, but no one uses that much alcohol.  And it assumes you are wearing gloves and not transporting fresh oils from your fingers while washing.

Consider a single gallon of water is 3780 ml (yeah, had to look that up) ...so nearly 1000 times the volume of alcohol most people use, and you get about 3 gallons a minute from a tap.  Alcohol doesn't even come close to the cleaning power of a sink.

But I am done on arguing.  People who refuse to use soap and water eventually end up sanding their PEI sheets.  

RE: PEI Cleaning and Temperature

Posted by: @charles-h13

[...] I would like to a user produced definitive guide to cleaning.  

Here's mine. I need to make an editing pass, but the basics are there. 

Just to avoid any confusion: The ScotchBrite pads come in a wide range of abrasiveness. The 7445 pads I recommend are used for polishing glass and chrome. (Made my phone and tablet displays look quite new, in fact!) The kitchen sink green pads are a hell of a lot more abrasive.

RE: PEI Cleaning and Temperature

Posted by: @tim-m30

The key here is volume; and that PLA is organic based (a material made from plants) and alcohol does a poor job dissolving the sugars released during printing.  Also, it dissolves oils into solution, which means oils remain when you wipe it away. You still leave a film on the plate, no matter how you wipe it off.  The only way to reduce the film is with dilution, and that takes volume.  And that is why running water at a sink works best.   

More information to add to your argument. Soap (of which Dawn is) is a surfactant. It actually suspends the oil as little droplets in the water so most of the oil is gone in the first rinse. That is just how soaps work. Much better cleaning mechanism than simple dissolving and rinsing.

I see that @bobstro also covers this on his Muppet Labs webpage.

RE: PEI Cleaning and Temperature

Alcohol. Another method of dissolving stubborn kitchen grease is to use isopropyl alcohol. Isopropyl alcohol works in a similar manner to water-displacing lubricants. It breaks up the grease into smaller particles and surrounds it with alcohol molecules, in effect dissolving the grease.

Detergent. The head of the grease molecule is attracted to water (hydrophilic) and the tail is attracted to grease and dirt (hydrophobic). When the detergent molecules meet grease on clothes, the tails are drawn into the grease but the heads still sit in the water.

The mechanisms are so similar it doesn't really matter except to a chemist.

RE: PEI Cleaning and Temperature

Detergent works like bile in your gut.  Like indicated above, it allows smaller droplets so that they can be pulled away by the solution.  In this case, the smaller droplets are easier to whip away or be absorbed by the  paper towels,   It is a situation of creating more surface area with more droplets.  

RE: PEI Cleaning and Temperature

Detergent works like bile in your gut.

Alcohol works wonders in my gut, but Dawn does not. Therefore, by Bunny Science, bile would also be great for cleaning the print plate, but collecting enough pure bile has proven difficult.

RE: PEI Cleaning and Temperature

I just tried an experiment on my >1 year old PEI sheet that has been horribly abused.  Meguiar's Plastic Cleaner 17.  

There was an odd reaction, the cleaner almost immediately pasted up; when it normally acts more like a wax and wipe on then buffs off.  But it had cleaned the PEI sheet incredibly well when I rinsed it off.  Since the 17 is slightly abrasive (removes swirls and cloth scratches from optical acrylic and plexiglass), it also improved the PEI sheet appearance. lol. And no, I'm not using it again.

RE: PEI Cleaning and Temperature

Posted by: @tim-m30

I just tried an experiment on my >1 year old PEI sheet that has been horribly abused.  Meguiar's Plastic Cleaner 17.  

There was an odd reaction, the cleaner almost immediately pasted up; when it normally acts more like a wax and wipe on then buffs off.  But it had cleaned the PEI sheet incredibly well when I rinsed it off.  Since the 17 is slightly abrasive (removes swirls and cloth scratches from optical acrylic and plexiglass), it also improved the PEI sheet appearance. lol. And no, I'm not using it again.

 

How are the prints now?

RE: PEI Cleaning and Temperature

This was a rather recent test - but prints are still working well. Good adhesion etc.  I really can't recommend the cleaner because the improvement in adhesion was minimal and the risk of actually damaging the surface.  I was trying to eradicate a mistake made months ago (a solid ring scratched into the PEI while doing some Live-Z tests - and I had nothing to loose by trying.  

RE: PEI Cleaning and Temperature

Posted by: @tim-m30

[...] and I had nothing to loose by trying.  

That's basically where I am with the textured sheet. Still haven't found an answer. Maybe I will break out the 200 grit sandpaper...