ACETONE AND COLORFABB RED TR FILAMENT EXPLAINED AGAIN....HOPEFULLY A BIT BETTER
Ok so I have a bit of time spare during my night shift so I thought I'd have another go at explaining how things work and how I go about my post processing as simply and clearly as I can.
Ok so first up, the whole PLA and acetone argument and purity of PLA and different filaments.
I am not trying to say PLA smooths with acetone, because we all know that it doesn't. Some people seem to have some focus on the purity of PLA and wanting to acquire the purest form of PLA yet have no real idea of what EXACTLY is in the PLA they are using anyway which kind od defeats their argument to begin with. We are not buying narcotics here, so purity is not really a factor, but consistency of filament production is more important and that the manufacturers don't change the formulas half way through a batch as this will affect future post processing efforts. Colorfabb is NOT the only filament that smooths with acetone, many others do, but I am concentrating on Colorfabb because I know the filament well and their formulas are fairly consistent from using that brand for the past 3 to 4 years.
The resolution you print at before applying the acetone is the most important factor.
I print at 0.06 and find that although every line may not smooth perfectly due to serveral factors, clean up is FAR less painful and monumentally quicker that simply applying filler and sanding multiple times. Longer printing times mean smaller post production times, a lot smaller. Sometimes if I have even one error on a print I will print it again because I don't want to waste my time sanding and filling for hours on end.
Sanding.......yes you still have to sand your prints.
But with much finer sand paper which makes sanding minimal and not a total pain in the arse. I don't like to apply any filler or topcoats of various materials, as I tend to plate my work and this is a pain to keep perfect in an acid tank as fillers usually absorb liquid and expand ruining any patches you may have fixed.
To patch up small holes and seams I simply use superglue and activator and then sand it out. I find it much better than filler although much more difficult to sand down, but the advantage is that you will be able to sand it down perfectly and NOT see any seam whatsoever. Also superglue does not react to acid or other top coats. You can just spray primer and sand down the slight imperfections and it will usually be OK. No needs for stupid amounts of time wasted sanding. I've read people spend up to 3-5 hours just spraying and adding filler to a tiny ball type object.....total waste of time in my opinion Just print higher rez.
Sanding soon after dipping or brushing will result in a powderless sand. As the PLA/PHA is still absorbing the acetone, it is much more flexible and it is kind of possible to rub the surface smooth with the sand paper in a way that you are sanding but merely rubbing the lines out with the sandpaper and not causing any actual damage. Its hard to explain but you will see what I mean if you try it. Doing this kind of sanding takes longer to the surface being more resilient to fine sandpaper but still vulnerable to markings from fingernails and sharp objects.
Usually when you sand an object then you go through grades of sandpaper, but again this is simply not necessary if you acetone your prints as you are removing the need for the harsh grades and skipping straight to 240 or 320 or even 400. I tend to use the same piece of 240 for ages and this simply means that it turns into a finer grade by being used up. Using fresh sandpaper can often be too harsh on the surface.
You are literally breaking down the chemical composition of the plastic and relying on the excess to melt into the gaps between the layers. If you go to hard on small pieces they will warp. This shouldn't come as a surprise. Dont dip or brush on for too long. A few seconds is sometimes enough. More than 45 seconds is pushing it, and a few days or months down the line when the acetone has finally evaporated off or been absorbed, the model may plit crack or warp further.
I believe this is some form of oxidisation, and if the acetone is left in tiny gaps, then the PLH/PHA impurities may collect and obstruct detailed areas (which is what you dont want), so make sure to coat the object evenly and not let the acetone sit for too long. It can look deceptively ruined, but a quick primer run will surprise you how its pretty much only superficial. If you need a clean look and are not spray painting it, go down the Ethyl Acetate route but again, its a different chemical so different rules apply for this, that im not getting into at the moment.
I'll finish it there for now. But I hope that helps anyone out there to at least get started. Ill post a new vid applying to another large print and show you the results.
And don't use nail varnish remover its too weak. use as close to 100% Acetone that you can get hold of.
....And dont blame me if it doesn't work for you. It just means you are doing something wrong! or for too long!
And remember have fun experimenting!!!! safely of course, if you find your throat hurting when you go to sleep, its because you were not wearing a protective mask, or the wrong one. Also remember nitrile gloves, but these are only effective for like 10 seconds.......so be quick!
So do a test for yourself, Print a small object in 0.06 layer height in colorfabb TR red PLH/PHA and then dip half of it into acetone for like 10 secs and wait for the surface to harden. Then spray it with primer and see the results for yourself. However this isn't magic and if you are useless at post processing or light sanding then don't even bother and simply accept that your prints will have visible layer lines....and mine won't! 😛
I will ahve to agree that I have used CPE and PETG with no issues. I am not fond of CPE for other reasons than the way it prints. But my experiences with PETG have been no issues. But I would not use Esun because it seems to be a bit cheaply made and not up to rigorous standards.
I dont have ESUN PETG but I print with CPE and PET+ and I run them at 245C and around 50mm/s on a UM3 and I dont have under extrusion. Even the CPE+ black from UM also prints well at 245-250C. This might be lame but have you tried increasing temp and decreasing speed?