"Rough" first layer after several near-perfect ones
I've been printing on my Mini+ almost nonstop for about 6 weeks. Mostly PLA, but a few PETG items. Prusament, Overture, and Sunlu PLA have all printed fine. Tonight, I printed a Spirograph set, and the only way I can describe the first layer is "rough." I wasn't able to get a photo of the top side of that first layer (phone was dead), but here's a photo of the bottom after it finished. I noticed that by the 4th layer, things were back to their normal smoothness. But the 2nd layer seemed like it was having to negotiate the roughness of the first. Before this print, I had just cleaned the print sheet with IPA and let it dry. In the attached photo, you can see an almost perfectly smooth area toward the right side. This is what my prints have been like until this one. Any idea what could be the cause or how I can get back to that smoothness? The top left area concerns me the most. 
RE: "Rough" first layer after several near-perfect ones
I would start with the least involved and most likely assumption that it’s either Live Z that needs to be recalibrated or dirty steel sheet.
To get Live Z right, don't use the in-built method, as the small square is hard to read, especially if you're not experienced. Use this instead: https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/
To clean the sheet properly, use hot water and fragrant-free dish washing soap. Dry with a paper towel. Before use, clean it with 90+% isopropyl alcohol. See this thread for a more in-depth discussion:
https://forum.prusa3d.com/forum/english-forum-general-discussion-announcements-and-releases/satin-spring-steel-sheet-pla-prints-dont-stick-anymore/
Ignore the title, everything in there applies to all types of steel sheets.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: "Rough" first layer after several near-perfect ones
After reading and looking at more photos, I backed off on the Live Z (moved it away from the print bed) just a little bit. Started another print that has a pretty big first layer, and it's looking nice and smooth so far...
RE: "Rough" first layer after several near-perfect ones
Not perfect but close.
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Chuck H
3D Printer Review Blog
RE: "Rough" first layer after several near-perfect ones
@cwbullet
Still too close, or not close enough? Compared to where I started, it was like glass.
RE: "Rough" first layer after several near-perfect ones
@andye
It is hard to tell from the image. If it is smooth then I am seeing an optical illusion created by the camera.
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Chuck H
3D Printer Review Blog