Notifications
Clear all

PEI bed cleaning methods  

Page 1 / 2
  RSS
Vojtěch
(@vojtech-3)
Honorable Member
PEI bed cleaning methods

Since there are a lot of opinions on how to best clean the PEI bed for good adhesion, I thought it makes sense to create a separate thread for the topic. The methods I've seen recommended:

  • Cleaning with isopropyl alcohol and a paper towel. It seems that the grade and purity of the IPA and the quality of towels plays a role.
  • Cleaning with off the shelf alcohol wipes. Apparently, the results are mixed as the liquid on the wipes varies.
  • Washing in isopropyl alcohol by pouring it on. This is a method classically employed for cleaning PCBs from flux/rosin.
  • Washing it in hot water and dish soap. Apparently works great, but there are reports of rusting. Perhaps this applies only to the older spring steel sheets without the dark paint underneath the PEI.
  • Washing in hot water after spraying kitchen degreaser spray on it. (Vojtech)
  • Cleaning with acetone and a paper towel. 
  • Washing in acetone.
  • Using a Scotch-Brite kitchen sponge. (Joan)
  • Using a 3M 7445 Scotch Brite pad. (Bob)
  • Using a 1000 grit sand paper. (Chris)

I think everyone would agree that the purpose of cleaning is to expose enough of a surface area of fresh, unoxidized PEI to the melted plastic, removing:

  • Oxidized PEI
  • Previous plastic residues
  • Fingerprint fat
  • Any lubricants (silicone oil, mineral oil) possibly coming from bearings/rods
  • Previous application of PVA glue or any other sprays/liquids
  • Others (sugars, dust, ...)

Each of the methods may be more or less efficient at removing each of the contaminants.

There are a lot of theories why one or the other doesn't work. But experimental results are what matters in the end. So I'll start with a photo of a Bed adhesion test model printed  with on a bed intentionally smudged by skin fat and then cleaned by wiping it using 99.9% IPA on a lint-free single-use towel. It worked just fine:

Posted : 04/05/2019 10:42 am
Cotton and liked
klaus.h5
(@klaus-h5)
Active Member
RE: PEI bed cleaning methods

switched fom acetone to window-cleaner ("Frosch (r) Spiritus Glas-Reiniger" here in Austria).

It's early days but it seems to me that acetone "broke" Side A of my smooth PEI (could not -for the life of me- get anything to stick to it), the "frosched" Side B of same sheet works like a charm.

I'm at about ~40 hours on this side, stickage during print is very good (plus no excessive force needed to get the print off it) but I mainly print with PLA and PETG, so YMMV.

Will try the linked adhesion-thingamajig with a "Frosch-PEI" and report back.

 

 

Posted : 04/05/2019 11:39 am
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods

Is there anything visible on the side damaged by the acetone? Does washing it with a kitchen detergent and a lot of hot water recover it?

Posted : 04/05/2019 1:06 pm
klaus.h5
(@klaus-h5)
Active Member
RE: PEI bed cleaning methods

Followup as promised:

Filament: Verbatim 55250 / PLA Black (just because of the visibility against a black bed *ahem*)
Slicer: 1.42.0.-beta2+linux64.appimage
Slicer-Settings:0.15 [Speed|Quality] (I'm really sorry but I didn't pay attention :-()
Print Time: 01:05 

Result: see image, _after_ somewhat carefully removing the PEI from the printer (bed-temp: 20°C) it just needed a "slight push" and it came off

TL; DR: Frosch seems to work for me 😉

Attachment removed
Posted : 04/05/2019 1:42 pm
klaus.h5
(@klaus-h5)
Active Member
RE: PEI bed cleaning methods

@vojtech: 

depends on "damage": I do see some lines from previous prints but I cannot feel them when I "scrape" over them with a fingernail.

I haven't tried to give the bed a whirl in our dishwasher yet 😉

PS: "use dishwasher detergent" is awfully misleading, which one do you mean? there are ones which claim to ".... include skin-restoration elements ...", others seem to be vegan and the third one says ".. we did not kill baby seals!" (OK, I invented the last one but you get my drift)

 

 

Posted : 04/05/2019 1:57 pm
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods

Regarding the dish soaps. Those liquid ones that one used when washing dishes by hand. Typically the cheapest work best. As little additives as possible, just the ionic and non-ionic surfactants. 🙂 You definitely want to avoid the skin-restoration components, that's fats again which you're trying to remove. Regarding baby seals, I guess that's your own decision. 🙂 I myself am using a kitchen degreaser, I had good success with these two: Bril Degreaser and Mellerud Kitchen Degreaser.

Posted : 04/05/2019 2:13 pm
bobstro
(@bobstro)
Illustrious Member
RE: PEI bed cleaning methods
Posted by: Vojtěch

Since there are a lot of opinions on how to best clean the PEI bed for good adhesion, I thought it makes sense to create a separate thread for the topic. The methods I've seen recommended:

I did a deep-dive on this and have at least a layman's understanding of some of issues that has been borne out with some casual testing. A qualified chemist will probably take issue with some of my terminology, but this is the gist of it.

  • Cleaning with isopropyl alcohol and a paper towel. It seems that the grade and purity of the IPA and the quality of towels plays a role.

Alcohol acts as a solvent for accumulated grease. The more concentrated the solvent, the more effective a given volume will be. Thus, 71% alcohol wipes work, 91% works better. Consumer-grade solvents won't break grease down completely, just enough to ease removal. Unless you've both broken the grease down and physically removed it, adhesion will remain poor.

As important is the volume of solvent (alcohol). New users are happy that 71% wipes work on a fresh new sheet with little accumulated grease, then get frustrated when it seems the sheet is "wearing out". It's not, there's just more accumulated crud. Moisten a paper towel and wipe the PEI sheet and you'll get some of the grease. Squirt a greater volume onto the sheet and wipe away from the print area and you'll get more. It's the amount of solvent as well as concentration that matters. Too little of either and you're likely to get unsatisfactory results. If all you have is 71% alcohol, expect to use more of it for the same results.

  • Cleaning with off the shelf alcohol wipes. Apparently, the results are mixed as the liquid on the wipes varies.

The concentration is usually low (~71%) and there's just not that much on the wipe. Not to mention, you're just moving broken-down grease around with a tiny wipe, so more is likely to stay in the print area. A small wipe with lower concentration alcohol is probably the worst case for cleaning a heavily-used PEI sheet.

  • Washing in isopropyl alcohol by pouring it on. This is a method classically employed for cleaning PCBs from flux/rosin.

Before I decided to figure out what was really going on with PEI cleaning, I'd moisten a towel with 91% isopropyl alcohol and wipe the sheet. It usually worked well, but there would be persistent spots. Once I realized volume and actually removing broken-down grease was critical, I picked up a wash bottle to dispense more alcohol where it is needed. I then wipe the bed and make a point of moving away from the print area. Results have been much more consistent.

  • Washing it in hot water and dish soap. Apparently works great, but there are reports of rusting. Perhaps this applies only to the older spring steel sheets without the dark paint underneath the PEI.

This is what finally clicked for me. How is mere dish soap so much more effective than concentrated isopropyl alcohol or acetone? Volume. There's just so much more soap and water being used to wash and rinse that more likely to break down grease sufficiently and wash it away. Joan had mentioned that a dunk under the sink washes the grease away months ago, and the technical explanation supports the observation. Dawn isn't magic, there's just a lot of Dawn and water using this method.

As to rust, I think that comes down to drying properly. I've still got my original, much-abused PEI spring steel sheet and it hasn't rusted since April 2018.

  • Washing in hot water after spraying kitchen degreaser spray on it. (Vojtech)

I have never needed this, but I do wonder if it's the hot water doing the magic rather than the degreaser. Seems to back up volume being the key, as well as actual removal of accumulated broken-down grease.

  • Cleaning with acetone and a paper towel. 
  • Washing in acetone.

From my research, acetone just seemed to be a more concentrated solvent, but I think your note that it removes oxidation may be the key differentiator. Makes sense that too much can make the PEI brittle then. I'm looking for a specific reference to this. Good stuff.

  • Using a Scotch-Brite kitchen sponge. (Joan)
  • Using a 3M 7445 Scotch Brite pad. (Bob)
  • Using a 1000 grit sand paper. (Chris)

I only point out the 3M pads to avoid any suggestion of applying a used kitchen sponge! I've seen much coarser sandpaper recommended and cringe at the idea. I've never needed anything coarser than the pads to get excellent adhesion.

[...] There are a lot of theories why one or the other doesn't work. But experimental results are what matters in the end. So I'll start with a photo of a Bed adhesion test model printed  with on a bed intentionally smudged by skin fat and then cleaned by wiping it using 99.9% IPA on a lint-free single-use towel. It worked just fine:

I gave my PEI sheet a good clean, then made a point of avoiding touching the print area surface, being careful to use a plastic scraper to remove parts, skirts and prime lines. I was able to get a dozen or so prints between cleanings, even using matteeee's bed adhesion test print even with 0 (zero) infill and not using vase mode to increase nozzle interaction with the print at higher layers. Tthe part stuck firmly for many successive prints and removed cleanly each time.

It's worth noting that I'm getting consistent results using both Prusa and BuildTak PEI sheets. I haven't noticed any real difference between them. I have compiled my notes on troubleshooting adhesion here and cleaning the PEI sheet here. It's also important to note that Live-Z adjustment is a critical part of the adhesion puzzle. My notes here.

On the reddit 3D printing groups, there's a small contingent of "Anti-Prusites" who like to pop in and make snide comments about Prusa in general and creating confusion about the capabilities of the removable spring steel sheets in particular. More than once after explaining cleaning, I've seen responses of "this is why I stick to glass" or "glue stick is much easier". I put up this video in response. No spatulas, no chipping glass, no hairspray overspray, no goop or cleanup. Just wash, print and remove.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 04/05/2019 6:18 pm
holmes4 and liked
--
 --
(@)
Illustrious Member
RE: PEI bed cleaning methods

We can start with the simple fact a stock, new, clean PEI works very well: plastics like PLA adhere and allow for great printing results little fuss.

Things that get on the sheet are finger prints, plastic residues, and the PEI itself oxidizes with heat.  And, with accidents, oil and grease from over zealous lubrication.

Other things we can agree on:

A sink faucet operates at 3-6 gpm (in the states). Soap is a surfactant and causes material to lift from surfaces. Water acts to dilute the soap and and rinse soap and lifted material away.

Alcohol is non-discriminate: it thins oils from your fingers as well as from another surface, unless you are wearing gloves. The oils go into solution, and residual oil remains in the evaporate. PLA is soluble in alcohol (and water). 

Acetone is also non-discriminate. Oils dissolve and remain in the evaporate. PEI is soluble in acetone (and a few other plastics, like ABS).

Abrasives, whether a scrubber dish sponge or sand paper non-selectively abrades material and mars the surface with scratches. Sanding does not remove oils or other contaminants, nor does it remove the abraded material. It simply moves everything around. Washing is still required to fully clean the dust from the sheet. And it is impossible to say if the sanding helped or the wash was the effective action.

A smooth PEI sheet is great for printing parts that need a smooth, even glossy surface.

A textured PEI sheet is great for printing parts that need an embossed surface.

Sanding a smooth PEI sheet will yield a directional matte finish.

Sanding a textured PEI sheet will result in exposed steel at the peaks, and have no effect in the valleys of the texture.

Since sanding can't help textured sheets, and it still requires a wash, we can ignore it as wasted time and effort, and it always damages an otherwise good PEI surface.

If we consider oils from fingerprints the more common cause of insufficient adhesion problems, the question becomes "What is the best way to remove the oils from the sheet surface?"  

If we consider one fingerprint, 50 micrograms of oil on a surface, and use 1 gram of alcohol (about 1.25 cc): we get a solution of 50ppm. When we wipe away the oil a layer of alcohol remains and evaporates, leaving a fine film of oil (at 50ppm).  If instead we rinse for 30 seconds in water at 5 gpm, we get a bit better dilution: about 0.005 ppm. 18,900 times less oil remains. If we rinse for a minute, it's half that.  Pretty easy to see it will take a lot of alcohol to equal the cleaning ability of soap and water.

So here's my take on what to use and when it may help:

Hot Water wash: often, as needed 
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 rinse: every few prints
Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils.
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.

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. If you see any streaks, the bed is dirty and needs a wash.

Acetone wash: infrequent
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.

This post was modified 2 years ago by --
Posted : 04/05/2019 8:02 pm
Sembazuru and liked
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods

@Bob: I had hoped we'd stick to facts and not postulates and theories in this thread, but given we're already there, let me postulate this:

In a very simplified scenario, where you have a stained plastic on one side and a volume of solvent and let it reach an equilibrium, the main variable is indeed the volume of the solvent as the affinity of the fat and to the surface get balanced with concentrations.

In a scenario, where you have stained plastic, a solvent as a medium, and a paper towel as another surface between which the solvent allows transfer of the fat, you end up with an equilibrium of fat on plastic, fat on solution and fat on paper. Given that paper has a much bigger surface and a much bigger affinity to fat, it actually will adsorb the majority of the fat. Obviously it cannot be reused, but is removing most of the fat.

Another effect at play is the evaporation of alcohol in during the wiping process. As it does so, the alcohol moves towards the top surface of the wipe, carrying the fat with it, removing it from the plastic. For more detail, look at how chromatography works. It may actually be beneficial if the plastic is hot while wiping. I need to check that, I usually do it while heated.

I believe the reason the concentration of the solvent is important is twofold: Water in the solvent blocks solution of fat significantly, to the point where at a high percentage of water, fat would just separate. And second reason is that non-pure solvent tends to contain not just water, but all kinds of other impurities in it from the start.

As for soap: It's not just the volume of water. Soap is not a solvent, it's a hydrophobic-hydrophilic interface that attaches to fat molecules and makes them soluble in water. So you do need enough soap to activate the fat and then enough water to remove both the activated fat and the excess soap. But adding more water will not help removing any remaining non-activated fat. And again, there will always be some, because it'll be an equilibrium of affinity of the fat to PEI and to soap.  Still it's a very effective method.

About degreasers: These are just stronger soaps. A mix of ionic and non-ionic surfactants, including strong ones like fatty alcohol ethoxylates. No fragrances, no thickeners, no skin protection additives.

On acetone: Acetone typically is sold at near 100% concentrations, but it's not just the concentration. It's a stronger solvent, less polar, more readily attacking other molecules. Including PEI, helping to expose fresh surface. Faster evaporating, too. About cracking PEI, I've seen the cracks develop in front of my eyes on my (non-prusa) textured PEI sheet after applying acetone. It still works, though.

About sanding and scuffing: they help remove the top layer of the PEI sheet, which may contain non-soluble contaminants. It may eg. be infused with other plastics from previous prints. If one was printing PLA exclusively, that'd be fine, but for example PLA and PETG don't stick to each other all that well. It's never been about removing oils. Not everything gets activated by soap nor is soluble in water, alcohols and acetone. Plus it may increase the surface area of the PEI, resulting in a bigger contact area with extruded plastic. Sanding a (clean) PEI surface is a last resort, but reliable way to revive a PEI sheet. It can also remove some surface imperfections. Another benefit is that fingerprints are so much more visible on a sanded surface. 😉 I wonder if it can be polished back to glossy if needed.

 

Posted : 04/05/2019 9:47 pm
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods

@Tim: I don't think it's the metal that provides texture in the textured PEI surface, it's just the way the powder coating is applied to a smooth metal sheet.

Posted : 04/05/2019 9:51 pm
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods

@Tim:

If we consider one fingerprint, 50 micrograms of oil on a surface, and use 1 gram of alcohol (about 1.25 cc): we get a solution of 50ppm. When we wipe away the oil a layer of alcohol remains and evaporates, leaving a fine film of oil (at 50ppm). If instead we rinse for 30 seconds in water at 5 gpm, we get a bit better dilution: about 0.005 ppm. 18,900 times less oil remains. If we rinse for a minute, it's half that. Pretty easy to see it will take a lot of alcohol to equal the cleaning ability of soap and water.

Cool and easy to understand example.

There are several problems with it, as is usual with simple examples. The biggest being that water will only act on the soap and soap layers engulfing fat droplets. Any fat that is not agitated enough will remain on the surface and excess water will not dissolve it once the soap is washed off. So your 0.005 ppm calculation doesn't make any sense.

Mind you, I'm not saying that soap and water isn't an excellent method. Only that it isn't several orders of magnitude better than a solvent.

And I'm wondering how to set up an experiment to support or refute my claims. I'm thinking I could try measuring the removal force of a print with a nominal contact surface area ...

Posted : 04/05/2019 10:04 pm
bobstro
(@bobstro)
Illustrious Member
RE: PEI bed cleaning methods
Posted by: Vojtěch

@Bob: I had hoped we'd stick to facts and not postulates and theories in this thread, but given we're already there, let me postulate this:

Heh. OK. You win. I'm just trying to help people having problems by explaining what works and giving them a sense of why. Have fun.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 04/05/2019 10:16 pm
--
 --
(@)
Illustrious Member
RE: PEI bed cleaning methods
Posted by: Vojtěch

@Tim: I don't think it's the metal that provides texture in the textured PEI surface, it's just the way the powder coating is applied to a smooth metal sheet.

Never said what you think I said; it's a powder coating of or over which PEI is applied. Fact remains sanding only affect the 2% peaks, the pits in the surface are not affected by sanding.

Posted : 04/05/2019 10:49 pm
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods
Posted by: ...
Posted by: Vojtěch

@Tim: I don't think it's the metal that provides texture in the textured PEI surface, it's just the way the powder coating is applied to a smooth metal sheet.

Never said what you think I said; it's a powder coating of or over which PEI is applied. Fact remains sanding only affect the 2% peaks, the pits in the surface are not affected by sanding.

Sure, sanding there doesn't make sense as you can't reach the valleys. I just don't think that sanding the peaks can expose steel, because steel is below valley level.

And it's actually a PEI powder that's applied with a powder-coating technique. Quite possibly there is nothing else underneath. But I'm not yet ready to destroy my sheet to find out what's inside.

This post was modified 2 years ago by Vojtěch
Posted : 04/05/2019 11:16 pm
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods
Posted by: bobstro

Heh. OK. You win. I'm just trying to help people having problems by explaining what works and giving them a sense of why. Have fun.

My apologies, it's not my goal to win. I'd just like to find out what's real and what's beliefs, including mine. But perhaps for that I should simply invest time and do the measurements.

Posted : 04/05/2019 11:20 pm
klaus.h5
(@klaus-h5)
Active Member
RE: PEI bed cleaning methods

wow...

what @bobstro said makes sense to me ("much helps much" ;-))

I absolutely will give this a try (also on my "broken" Side A, see above) as soon as I'm able to nail down the damn "THERMAL RUNAWAY".

/note to self: never ever ask about vi vs emacs here 😎 

 

Posted : 06/05/2019 4:45 pm
vintagepc
(@vintagepc)
RE: PEI bed cleaning methods
Posted by: klaus.h5

/note to self: never ever ask about vi vs emacs here 😎 

Oh great, now you've done it... 😀

Posted : 06/05/2019 4:57 pm
bobstro
(@bobstro)
Illustrious Member
RE: PEI bed cleaning methods
Posted by: klaus.h5

/note to self: never ever ask about vi vs emacs here 😎 

Nah, so long as you're running Linux we're all good.

That would be Debian Linux of course.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 06/05/2019 6:48 pm
vintagepc liked
vintagepc
(@vintagepc)
RE: PEI bed cleaning methods
Posted by: bobstro
Posted by: klaus.h5

/note to self: never ever ask about vi vs emacs here 😎 

Nah, so long as you're running Linux we're all good.

That would be Debian Linux of course.

#RPMMasterRace

Posted : 06/05/2019 6:59 pm
Vojtěch
(@vojtech-3)
Honorable Member
Topic starter answered:
RE: PEI bed cleaning methods
Posted by: bobstro

That would be Debian Linux of course.

Oh! Then I'm done for ... no hope for me!

Posted : 06/05/2019 7:33 pm
Page 1 / 2
Share: