PLA Blend and PETG leave permanent marks on plates  

RE: PLA Blend and PETG leave permanent marks on plates

I skipped the 'basic' plate, so can't comment on that, but the satin plate is in constant use here.

Those are normal. They do go away somewhat with IPA cleaning. Nothing to worry about.

Satin build plate with faint outlines of previously printed parts

Worth noting, all plates are considered consumables, so long term discoloration would also be par for the course.
So far I have not noticed any deterioration of the plate's holding capability. I guess what happens is mostly that the part takes any particles/substance that might be on top of the build plate with it, thus leaving an outline.

In that context: beware of finger prints, they contain some amount of e.g. fat/grease naturally and will greatly affect holding capability, to the point where the first layer won't stick at all. Whenever I notice them anywhere near the part of the plate where I will be printing, I make sure to wipe with IPA.

RE: PLA Blend and PETG leave permanent marks on plates

Posted by: @dp-2

The same with printing with PETG ( www.prusa3d.com/pl/produkt/prusament-petg-prusa-galaxy-black-1kg ) on a Satin plate ( https://www.prusa3d.com/product/satin-powder-coated-print-sheet/ ). First print resulted in such marks (I have not tried to clean it with isopropanol yet, waiting for your advice) :

In both cases I used nozzle and bed temperatures within ranges printed by Prusa on filament stickers.Did I damage these plates permanently? Do these mark deteriorate plate output quality/adhesion? Before printing I checked and these plates are dedicated for these filaments for use without any adhesion/separation layer. What am I doing wrong? Or maybe this is normal and simply requires some special cleaning proces???

You should not use the smooth build plate with PETG -- or use glue stick on it to reduce the stickiness. The satin plate is preferred if you do not want to mess with glue etc. See Prusa's material guide, https://help.prusa3d.com/filament-material-guide

In severe cases PETG can stick to the smooth plate so strongly that you rip the PEI layer off the plate. But in your pictures it looks like the plate is still usable and the marks are just cosmetic.

I don't have experience with PLA Blend. Prusa seems to treat it the same as their regular PLA, so it should work with the smooth PEI sheet without any further consideration. Have you tried removing the residue with warm soapy water instead of alcohol?

RE: PLA Blend and PETG leave permanent marks on plates

Thank you guys. (Yes I would not dare to print PETG on smooth).

RE: PLA Blend and PETG leave permanent marks on plates

Posted by: @dp-2

Thank you guys. (Yes I would not dare to print PETG on smooth).

Oops, sorry -- I had scrolled past the text between the two pictures in your original post. So you are in good shape, with just cosmetic residue left on the plates. Trying warm water with a bit of dishwashing soap is still worthwhile if you want to reduce the PLA residue.

RE: PLA Blend and PETG leave permanent marks on plates

Warm water with dishsoap and maybe even a very very slightly rough sponge/cloth work a lot better, than IPA.

However, if you need to print something with a nice looking surface and the old marks are visible:

Print 2-3 layers over the area your "beauty-print" will need, with a bit hotter nozzle and bed. Like 235/70 for PLA. This took away the old marks in many cases for me and replaced it with a bigger mark, I could print inside of to get no imprints.

Btw, with the Core One that doesn't really suffer from uneven bed surface, lower adhesion, uneven bed heating etc., I try to print on the edges, to save the center for beauty-prints. 

Printing in the back works a bit better on my/the Core One, than towards the front.

But I also have each build plate 2x. One only for really nice looking prints, where I really try not to plaster the whole sheet with marks. And the other where I absolutely don't care and just hit print. 

RE: PLA Blend and PETG leave permanent marks on plates

Thanks for the hints.

RE: PLA Blend and PETG leave permanent marks on plates

I come to believe its normal to have those terrible white marks, i was in denial at first...
For parts that the 1st layer must be perfect, i did a trick last time and worked very well.
It was on smooth PEI sheet and PLA material, after printing i gently heated the part with a heat gun (hair dryer or lighter will work also), and the marks faded almost 100%.
Just be very careful not to insist as PLA for example deforms fast, let it cool first before trying again.

Now i am thinking of heat treating my plates too and see what happens.

RE: PLA Blend and PETG leave permanent marks on plates

White plastic 'discoloration' is usually caused by mechanical stress. It causes the plastic to recrystalize into small crystals that appear white. As Samael points out one easy way to get rid of it is very brief heat exposure of the surface, to force another phase transition.

For PLA I've heard of people getting away with just running very warm/hot water over it, as the glass transition temperature is just 55-60 ºC. Any longer exposure to water of a temperature beyond that will inevitably start softening the material as a whole of course.

Apparently you can even temporarily make UV damaged plastic objects look nice again by briefly heating the surface. Supposedly in most cases e.g. lawn chairs or stadium seats quickly go back to the damaged look though.