I've been fighting pla curling up on the edged of a large flat print I've been trying to make. I'm using an ender 5 pro with cr touch. Filament is esun pla+ black 1.75mm. I use cura to slice. I was initially using the rubber magnetic bed that comes stock with the ender, but that got destroyed last night. I bought a pei spring steel plate when I bought the printer, so I swapped that out. Before the rubber build surface got destroyed I had cleaned it and applied glue stick for my last attempt to print. I tried the print on the pei plate with no additional glue. I have tried 50, 60, and 65 degrees c on the build plate, and 205, 210, and 217 degrees c on the extruder. Ambient temperature where I'm printing is about 70 degrees f. I have the fan off for the first 4 layers, and 100 percent after that. My first layer is set at .3mm and .12mm layers after that. I tried reducing the infill from 99 to 75 percent but this last print failed before I hit the infill layers. I am not sure where to go from here. I am considering building an enclosure, as I figure that may keep the plastic from cooling unevenly. I am open to different build surfaces, if that's necessary. I have printed a bunch of smaller items with this printer in the past without problem. I used the cura suggestions and had all good results. I'd appreciate any ideas you guys may have.

Large prints tend to do that.  Print a 5-10 layer high wall/brim around it and see if that helps.

I personally use hair spray on glass and never have any issues.

Try your print on a raft and see if it keeps the dimensions you are aiming for.

Do yourself a longterm favor and do not ever use hair spray.  It gums up fans, bearings and stepper motors.  

Use a product called Vision Miner, it sticks your filament when it needs to be stuck down and releases when it is release time.  A year of using it in a 65 printer farm and we have had *zero* adhesion related failures.  It feels like magic but it is science.  (thats my tagline, lol!)

If you use Cura as a slicer, they have a plug-in that can put a round dot in any corner you indicate (or any other spot, for that matter), like a mini brim.

Otherwise, go with a brim.

But yes, use an enclosure or try to find some way of eliminating drafts.

Make sure you are printing the correct height for first layer. Find a bed level test print that will let you print at .2 or whatever single layer you want to use.

Am I better off going higher or lower with the bed temperature? I've seen people advocating both.

If prints are curling at the build surface then I've found a lower bed temperature is better.

I used to print PLA+ on the Creality glass bed (textured side) at 60 degrees bed temp the entire print. I dropped it to 55 during print and 60 first layer.

Make sure you have your first layer tuned right to ensure good bed adhesion. I glued a PEI sheet to the other side of my glass bed for PETG and ABS+ prints.

If your print is curling several layers high and at overhangs then you need more cooling or your minimum layer time is too low.

I've never really needed to use a brim with PLA, but definitely recommend it for ABS+ prints.

I've also never used glue stick or hairspray on the bed. I just clean it with 70% alcohol (99% evaporates too fast) after every print.

The only times that I’ve had curling on my Ender 3 the bed wasn’t clean enough. A quick relearn and I was back in business.

OP, when I got a printer almost a year ago, it was also an Ender 5 pro, and I also started with Esun PLA+ in black.  i have to say it is pretty good stuff and should treat you well - this whole curling and lifting thing is basically poor bed adhesion, and what I found to solve that were the following;

1: its cold, dont let cold drafts in, they can cause immediate loss of adhesion
2: make sure you are getting enough squish.  this really is the biggest one.  clean plate, dirty plate, whatever, if you have enough squish it will stick.  now I dont have the BL touch, i have the thing where I have to rotate the knobs underneath the bed manually, but get your Z alignment nice and tight.  
3: make sure the screw assembly in the back that hits the z offset bumper switch isnt loose and just moving around.

regarding printing, i found the esun likes it a bit hotter, maybe 212 degress 60 degree bed, but that might vary a bit by machine.  

watch the first layer go down - e.g. if using a skirt, as it is printing that first loop, i run my finger over it to see that the material is stuck down and not able to move just from my finger running over it.  check all the way around, as there are 4 corner adjusters and therefore one corner may be good and the others not to good.  watch the 2nd loop - does the material squish into the first or does it look like 2 parallel lines.  it should almost meld, due to the squish.  if not and your Z is truly good, you might have too little extrusion, but likely it is more like not enough squish.

make sure all 4 corners equally go down.

for PLA you shouldnt need brims or rafts etc.  a brim is a hack for materials that warp, which PLA doesnt.  if you need one you instead need to find the solution.  

my experience is with a glass bed.. ymmv. good luck

_{There is a plugin called anti warping in cura,}

This can definitely be frustrating. On one my first large prints (AnyCubic Vyper) I encountered curling issues as well. Experimented with a couple things, and was able to resolve it pretty quickly. But every printer and environment is different, so YMMV.

Below are things that worked for me printing on a magnetic PEI sheet.

1. Anti-warp tabs (which I think are unique to Cura). These are user placed, and can be adjusted for size as well. I would put them around the corners of the print (with a .16 X/Y distance).


2. Print with a brim. I also use the same .16 X/Y distance. Which eliminates the curling, but also makes it super easy to remove.


3. Adjust temps. This took some trial and error. And you've already started down this road. For me the sweet spot has been 205c for the nozzle, 65c for the bed during the initial layers, and 60c for the remainder of the print (I also use PLA+ exclusively, either PolyMaker or 3D Fuel brand).


4. Slow the first layers down. I use 20mm/s for the first two layers, and 25mm/s for the top and bottom layers. While using around 55mm/s for everything else in the print. I also don't run the fan for those first two slow layers.


5. Make sure your bed is really clean. I tried IPA and some other stuff. But the best hands down is dawn dish soap and warm water.


6. Control your environment. When printing bigger objects I place our little Vornado heater near the printer, but not blowing directly on it.

Of the above, I think the biggest factors were dialing in the temp and getting the settings for the first few layers right. Plus making sure the bed is really clean ahead of a big print. The anti-warp tabs or brim also did a great job on their own. But, I was OCD about fine tuning to the point where I didn't absolutely need them. Still, on larger prints where it won't hurt the end product, I'll toss a brim on there. It's added insurance and sure beats trashing a 20+ hour print.

Keep at it. It can definitely be frustrating, but there is a solution. Might take some time and cursing. But it's smooth sailing once you find that sweet spot.

See my reply above. For me it was going higher. I was originally printing at 55c bed temp. Ended up finding 65c for the initial layers and 60c for everything else works best. Thing that sucks is those advocating for each side aren't necessarily wrong. Just not a one-size fits all answer.

Working on an enclosure now to make sure its not an environmental problem. Doesn't hurt because I want to print nylon in the future. I will try cleaning the pei sheet thoroughly before I try again. It sucks that the problem doesn't show up until 4-5 hrs in. I appreciate all the help.