My glass beds are too clean for PLA?

[swbluto]

I take meticulous care in printing with the cleanest of clean glass beds, including periodic acetone washes and a very specific way of cleaning with alcohol, damp rag and a dry rag. All my ABS prints stick to the glass bed flawlessly using this method with almost 99% reliability (Whereas if I don't take nearly as specific meticulous care, my reliability is somewhere around 80%. The cleaner the beds truly are, the better ABS sticks, I've experienced.)

However, I recently tried printing PLA on it, and it wouldn't stick at all! I tried making it super clean, including an acetone wash, and that just seemed to make the problem worse. Only two of my printers apparently have a "dirty enough" bed so that the PLA will stick, lol (I've read that PLA won't stick to an ultra clean glass bed.). Any ideas on how to make my bed 'dirtier' so that the PLA will stick?

I tried hairspray, and then washed it off with a rag, and it improved adhesion but the filament kept peeling off with the tiniest of persuasion. It'll print directly on hairspray buildup/gunk no problem, but the hairspray residue/buildup/gunk unacceptably dulls the appearance of the bottom layer. Any ideas on making my ultra clean glass beds 'dirty enough' for PLA without having junk on the bed affecting the bottom layer appearance?

(I'm thinking I'll just start touching my bed all over, lol. You're not supposed to touch your bed, so maybe that'll help? lol.)

Stats as of right now.

3 Glass beds are too clean (2 of them are pretty much brand new, I'm not really sure what's with my other one. I'm guessing I just haven't used it enough? Or maybe I've too recently washed it down with acetone...)
2 Glass beds are unclean just enough.

[insta]

I used to print on bare glass, but eventually had peeling problems. Now I use the adulterants -- a thin elmers glue wash (10:1) is my go-to for PLA-only, but hairspray works better as a universal covering. You can also wash the bed down with bottled mineral water while it's hot, to get a thin layer of impurities on it. Just grab a bottle of Evian from the gas station next time you're there, and use it at room temperature on a paper towel against a 60C bed, wipe around until the steam stops. Apply the elmers the same way.

That said, PLA is picky about bed temps. You want it 50-60C, no hotter. You want a fat & slow first layer, it seems van der walls forces hold the plastic down as much as anything. What settings are you using?

I typically do 0.2 layers, 150% layer height first layer, 200% layer width, 50% underspeed (of 80mm/sec), at 210C on a 60C bed. I'd go even slower on the first layer for bare glass, or use the elmers glue wash and laugh all the way to the bank.

[swbluto]

That said, PLA is picky about bed temps. You want it 50-60C, no hotter. You want a fat & slow first layer, it seems van der walls forces hold the plastic down as much as anything. What settings are you using?

I'm printing at 70C. Seems to work fine on the 2 printers whose glass beds do work. My speeds are pretty darn slow, about 13 mm/s. It seems printing speed (At the speeds I use, between 7mm/s and 15mm/s) has little relation with how well it adheres. It seems the state of the bed (In terms of cleanliness, whatever contaminants it has, etc.) is the major determining factor in how well it adheres. (In the case of ABS, a higher extrusion temperature helps I've noticed.)

I'm totally befuddled by this and I'm curious why it's printing out on two of the five but not at all on the other 3 (All of them print out ABS fine). Van de walls forces seems plausible, as well as the possibility there's residual plastic particles (Possibly of ABS origin) that've been 'baked' into the bed promoting PLA adhesion.

How do you mix your glue? Do you melt 1 part PVA glue into 10 parts boiling/hot-water and then spread the mixture? I'm wondering how one goes about achieving this ratio.

[swbluto]

I have the same experience with far less adhesion for PLA on glass when cleaning with acetone. Dish washing liquid, vinegar and a thorough rinsing in the sink works for me.

http://forums.reprap.org/read.php?1,146446,146868

Oh yeah, we got a lead. I'll try dishwashing liquid and vinegar soon on the offending plates.

[swbluto]

Okay, results are in. I tried out some of this "Trader Joe's Dishwashing Liquid with essential oils" and noticed it left a barely visible oily streak across the glass pane. I did my regular wet-rag/dry-wag clean up, and tried printing and it kind of worked! The adhesiveness definitely improved, but not well enough to avoid messing up. I'm starting to think my other (working) glass panes have oil on them from this particularly notorious black ABS I tried out one time on those panes (ABS wouldn't stick worth a damn after that,until I cleaned up with acetone.), and I think that's why they're working for PLA. Of course, the oil from the black ABS was baked into the glass pane during the entire 2+ hour print job, so I think that's the major difference from my 30 second application of dishwashing liquid with its oils that wasn't baked in. I'm not sure what oils, exactly, are effective for sticking the PLA to the glass, but it's whatever oils the cheap dishwashing liquid has.

Didn't have vinegar on hand, so couldn't test that out.

I guess oil would make sense, since "likes attract likes", and PLA is made from something corn like (Or whatever plant its made from). I guess baking on corn oil might be particularly effective? Might try it out.

(Damn, no corn oil nor vegetable oil in sight. My 'healthy food' loving family only has olive oil and coconut oil, two oils I don't really want to try, lol. I feel more comfortable with corn oil and vegetable oil since olive oil has a low boiling point, and coconut oil solidifies at room temperature.)

[Matt_Sharkey]

windex on a preheated bed works for me. I scrape any dust off with a razor first then windex it. I have problems with smaller parts, but use purple glue on the glass for those.

[swbluto]

windex on a preheated bed works for me. I scrape any dust off with a razor first then windex it. I have problems with smaller parts, but use purple glue on the glass for those.

Googling "windex ingredients"...

The Sam Wise patent [clarification needed] #3,463,735 lists example formulae, one of which is 4.0% isopropyl alcohol (a highly volatile solvent) 1% ethylene glycol monobutyl ether (a less volatile solvent), 0.1% sodium lauryl sulfate (a surfactant), 0.01% tetrasodium pyrophosphate (a water softener), 0.05% of 28% ..

Interesting. 4.0% isopropyl achohol and 1% ethylene glycol. In other words, isopropyl alcohol and sugar. Interesting that because I've used sugar with success to stick ABS prints, and I don't see why it wouldn't work with PLA, especially since corn (And most other PLA bases) is essentially sugar at the heart of it (Glucose).

I don't think my glass beds that are working have been coated with sugar at one time, but who knows. Something makes them different.

EDIT: Baking Vegetable Oil on the glass bed test concluded. Results: FAILURE. Lol, whatever adhesiveness that the dishwashing liquid imparted on the glass bed was utterly reversed by the vegetable oil, lol. I'm going to try some windex, next. (Or, push comes to shove, just add a little sugar to my isopropyl alchohol).

[swbluto]

So, one of the printers that could do PLA is now down for maintenance, so now I only have one that can do it. I switched out the "works with PLA" glass bed to another printer that didn't work, and I suspected it would work but... surprisingly... it didn't.

HUH, that's weird! I'm seeing three variables at play here.

Extruder temperature
Bed temperatures
Glass bed state (Which glass bed)

Since the glass bed state didn't change, I think, since it's the same bed, that directly points to a bed temperature cause or an extruder temperature cause. I guess I'll start up my remaining "Works with PLA" printer, and measure its temperature and compare that to the "not PLA working" printer, see if there's any differences. Measuring extrusion temperature seems unreliable at best, however, but I guess I should be able to detect huge differences.

(Btw, I'd highly suggest never letting vegetable oil near your printers. That is some nausea-inducing stuff that will contaminate everything it gets close to.)

[swbluto]

The bed temperatures were exactly the same (70C) but there seems to have been a difference in the extruder temperature. The highest temperature I could measure from the cartridge was 170-180C, while the printer thought it was at 210C, so I didn't have access to the temperature the temp sensor was measuring BUT it seemed like the "non working PLA" printer /might/ have been 5-10C cooler, on average. The "high average" (Measured on the top of the heated cartridge block) of the non-working printer was between 151-154C while the "high average" of the working was around 158-163. Don't know if it's a meaningful difference, but my experience with ABS suggests that if the filament isn't hot enough (Around 220C with ABS), it won't stick to the glass bed. On the other side, I don't really want to increase my extrusion temperatures too much because I believe PLA starts to burn and char at 220C.

Meh, a relatively small variation in the extrusion temperature between identical machines shouldn't be too surprising. Just sucks thinking about what steps I'll have to take to compensate for this.

Edit: Eh, the solution I came up with wasn't too bad. Still not sure, however. It could be that this roll of filament is "bad", even though it's the same filament from the same manufacturer. I'm testing that out.

Seems like this roll of filament is printing better. I wonder why that is... (Still lifted a bit, so extrusion temperatures might still be a little too cold but it's now actually printing something that has shape!)

Edit: Definitely the extrusion temperature was the problem. The reported extrusion temperature was the same between the machines (210C), but there was variation in the actual extrusion temperature. I had to set the machine to 235C to get it to print PLA well, whereas my two other machines print it well at 210C. Still testing, hopefully 235C will work out in the end and the traces won't spontaneously lift. Edit: 235C worked for the most part, but still a little lifting here and there. I'm guessing 250C will probably do it. I'm guessing I need these seemingly really high temps because of the exponential curve on the thermistor's temperature/resistance charts (A small difference in the coefficient results in a huge difference in the set temperature to get the same actual temperature.)

Edit: It appears 260C will be needed to achieve the same performance. Interesting, that, because another user on Amazon made the same comment about the same filament but two of my machines print PLA fine on clean glass at the recommended temperature of 210C, so clearly it's not the filament's fault. It's machines that we're both using that seem to be inaccurate 50% of the time at the high end of temperatures.

Well, 260C didn't really work out 100% as well (About 90% as well), as the entire print lifted later on due to some bottom layer part that partially lifted which the extruder dragged/pulled on later in the print. So, I'm trying out 260C in addition to windex. I noticed that windex had a sweet smell to it, while the dollar store variety didn't, and the traces are sticking noticeably better whereas the dollar store alternative didn't. Let's see if this combination shows promise. (Granted, you could probably replicate windex by mixing a little sugar with the dollar store stuff. It is the sugar that acts as the glue.)

Ongoing observation: Oh, the same corner lifted. It seems to have lifted /less/, so fingers crossed it doesn't screw up the entire print later on. If this doesn't work out, I'll try a 60C bed temperature and see if that helps.

Edit: The entire print eventually lifted, and lowering the bed temperature to 60C didn't seem to have any improvement (It actually seemed to decrease the adhesiveness, unsurprisingly.). I'm really curious about what's going on. Is 260C on this printer still not hot enough? Is it this particular roll of filament? I'm going to look into PVA glue more, now.

I think... I've just come to the conclusion that Hatchbox White PLA doesn't like to stick. I noticed that about half of my prints with this PLA on the makergear failed due to lack of adhesion, so it's not too surprising that my detailed bottom layer prints should fail with regularity on the other machines. Now I want to place these rolls of filament in a sealed bag with this collection of 30 dessicant baggies I've collected and see if that helps, lol. This PLA looks nice and prints nice (rarely 'burns'), but it seems 'slippery', just like pretty much all the black ABS I've tried. Luckily I have some other White PLA hanging around, and it definitely likes to stick, but it also likes to occasionally burn. I haven't figured out how to remedy burn marks, other than to avoid them altogether if you can.

[swbluto]

It's so bizarre how the White Hatchbox PLA sticks like none other to my first printer, but it barely sticks at all to my other ones. Granted, it appears the full roll doesn't stick nearly as well as the half-used roll even on this printer, but at least one of the rolls work. Wonder why the full roll doesn't work - I'm guessing because it's absorbed moisture from the air having been largely unused? Wish I had a sealable large bag just hanging around so I could seal it with some dessicants.

I'm guessing that my printer's extruder temperature is probably not 'too bad' because it seems like it works the same way with my ABS filaments between all of the printers, I'm guessing that it was a problem with the filament's moisture content. The reason why it seemed better at higher temperatures was because it was doing a better job of "drying" the PLA before depositing it. Granted, it didn't do a perfect job of drying it, and that probably helps explain why it wouldn't stick - whatever moisture content existed was making it too 'wet' to /really/ stick.

PLA seems to like clean glass beds, too, but the PLA needs to be really dry. That might explain the phenomenon behind some people's "glass beds just stopped working with PLA", it could be because the PLA absorbed too much moisture over time. Think I'm going to get some 2 gallon freezer bags that Target appears to have (13x16 I believe. Think that should be enough for one roll.).