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Acetone Finishing on PLA

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Posted · Acetone Finishing on PLA

I did notice that because of the hat on the model, the layer lines where much better than normal on the freddie models face due to it being shielded with support material, which indicates a wall around the object might beneficial in surface quality. both models were printed with identical settings one day apart. 

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Posted (edited) · Acetone Finishing on PLA

These photos show the effect of acetone on a part that I left on purpose in acetone for way too long (more than an hour), just to try what would happen. It got weak, lost its spring-effect, and cracked. Its strenght recovered somewhat in the next months when drying, but not fully. Now I broke it.

 

So you can see how deep the acetone penetrated and cracked the model. The inside seems to be still chemically affected, as it broke in a weird way, with very different inner and outer fracture surfaces. This is yellow PLA/PHA from colorFabb. The fracture surface is ca. 6mm x 4mm.

 

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Edited by geert_2

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Posted · Acetone Finishing on PLA

Yes indeed. Acetone goes deep. Deeper than Eddie Murphy going undercover in Bevery Hills Cop. 

 

It can also shrink. A lot! Ive done many tests on this. Its why you need to be very careful with exposure times and why brushing is less prone to warping than dipping which can play havok with hollow models.

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Posted · Acetone Finishing on PLA

Another thing is fire places and sources of intense heat or constant heat will affect the models a lot. The acetone tends to dry them out and intense heat even further causing rapid splitting. Also heating up a closed hollow model after acetonig can cause the model to inflate as acetone reaction seals the model from moisture... once you know how it reacts you can pre determine how to do things.

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Posted · Acetone Finishing on PLA

Not chatted on this topic for a while, but I've been having havoc with my curly hair lady, and had to repair it sooooo many times. I used tamiya putty to fill the cracks twice now, but realise what I had done wrong in the first place! I acetoned it with holes in the model and then proceeded to leave it in the window in full view of the sun, now I have many models in full view of the sun but the only ones that cracked were the hollow ones, so if your gonna acetone models like me and leave them in heat or the sun, they will crack. I have 6 year old hollow models that I've kept inside and they are fine, mind you in the room with my fire place I've noticed a few cracks. Its the acetone weakened walls that simply are drying out and splitting. once filled with plaster they are eternally damp inside so won't split in my opinion, maybe uv spray could prolong the hollow light and heat related splitting but who knows. I doesn't really matter. my unacetoned print look fine on the same window sill, but also most likely with my lady print, is that I glued 4 parts onto it, One arm, hand and the back hair bit and acetone got inside when doing my heavy brushing! When acetone gets inside your print it almost ALWAYS spells disaster in the long run.

 

one of my prints directly above my fireplace expanded like a balloon, looked well funny! I'll post a pic if i find it!

 

BTW That grey tamiya putty is the business!! goes on too thin, so nice! even though Id rather never use but in case you get tiny splits or something its soon easy filling them.

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Posted · Acetone Finishing on PLA

Hoi cloakfiend,

 

Have you ever tried *post-curing* an acetoned model? Thus: print, sand, acetone, wipe, dry, as usual, but then let it sit at an elevated temperature for maybe a day, or two days? The temp has to be above glass-transition temp, maybe 60-70°C, but below melting the model of course (may depend on the model what it can withstand). This could reduce residual stresses, so it might be less likely to split later on. And then primer, paint or plate as usual. If it is going to split anyway, it might already split during this process.

 

I am not sure it is going to work, or whether there would be bad side-effects, but it might be worth trying on a test model?

 

Another question: have you ever tried acetoning tough-PLA? This will have different additives than normal PLA or PLA/PHA, so it might behave differently? (I dont' have any tough-PLA, otherwise I would try it myself.)

 

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Posted (edited) · Acetone Finishing on PLA

No but I may do just out of interest, to be honest I have had almost no models split on me since i have stopped dipping and only using the brush on method. will try again soon, but im making much larger models than before so dipping becomes very inconvenient as I dont do my whole 5ltr acetone tank dip routine anymore!! lol. I have bought loads of paints recently and am painting my old skulls with flat matts lol. this skull is about 2 years old and has been above my fire place for a year, and its fine still. as well as the plated and patina'd one. I think its funny showing you an example of a smooth surface using one of the darkest flattest mattest paints available! still no splits! lol side by side for comparison.....Ill post non painted stuff when I get home! gonna slap a shiny laquer over the patina skull as well. just to see what it looks like!

 

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Edited by cloakfiend

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Posted (edited) · Acetone Finishing on PLA

Well here we are... reaaaaally old prints all avetoned and totally hollow and all in the same room. Basically colourfabb black was the worst. All black models split (the grey primed one) also my trex skulls but i forgot to photo those. (They were my first EVER) acetone experiments so ill make sure to photograph them too. Thats 6 years old! The rest are 1-4 years old my Red colorfabb was good. Brown poor like the black and marine blue was good and i acetoned the hell out of the blue!!!. The brown was ancient btw and I bought it on sale so no surprises there, but my lighter colours seem fine and I use them all the time even though ive had them laying about my house for years. Age only really affected the darker colours? Mind you I may have gone heavier on the black and brown but in hindsight all my acetoned black prints split ovet time. 

The pics... all brushed on no dipping. Ill do a test on something i dont like...but i cant really justify wasting time on things i dont like.... but il do it for you @geert_2!....I guess printing another kello kitty cant hurt. At least I can show you a nice quick way of filling the splits in a video. I haven't done one in a while!

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Light brown Colorfabb PLA/PHA (A FEW SPLITS)

“This product will be discontinued. Once there is no stock anymore no more products will be produced. Offer is valid until stock lasts.”

Special Price €19.97 for those interesed from their website.

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Transparent Red Colorfabb PLA/PHA (NO SPLITS)

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Ultra Marine Blue Colorfabb PLA/PHA (NO SPLITS)

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Black Colorfabb PLA/PHA (LOADS OF SPLITS)

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Traffic Red Colorfabb PLA/PHA (NO SPLITS)

Edited by cloakfiend

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Posted · Acetone Finishing on PLA

Thanks for the photos.

 

It might be fillers in the black that decompose due to the acetone? Or due to UV-light, or age, moisture, or whatever else? Or the fillers that reduce layer bonding, and thus make it more prone to splitting?

 

Also, I think manufacturer should mention in their specs for each filament: "Can be acetone-smoothed" or "Can be whatever-smoothed", and then the recommended product, time, method (brushing, wiping, dipping, vapour, whatever), and amount (thin, thick).

 

I have just smoothed a handle (using your brush-on method), yellow PLA, and now I am going to put it in the lab-oven to see what happens. First at 60°C for half a day, and then we'll see.

 

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Posted · Acetone Finishing on PLA

It could also be the primer paint?... often paint also contain solvents. Thats why the transparent colorfabb works so well it already has solvents mixed in. Generally, too much acetone releases these solvents and thus causes the cracking in my opinion but J really dont know? So many variables im doing a big print for work soon. I hope it doesnt split as its for live TV and would be a disastser! It aslo has to be solid at the base but flexible-ish at the top! More unknown territory for me then.... and multi part.. what do i get my self into lol. All because i love 3s printing. I always say yes to ANY job that requires it!

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Posted (edited) · Acetone Finishing on PLA

I was in my garage finally finishing my most split object ever. Took 2 days to print and ive spent about 4 days just fixing it over and over again learning how different solvents and fillers work together and sandability. I could have easily just printed again but i learn more this way and improve my filling sanding techniques. One thing i learnt was that you need to regularly wipe clean and regrease the main screw or else dust gathers on it which in turn create subtle unwanted layer lines. Also my garage umia like a desert. It gets freezing at night and hot in the day. These following objects have been there for over 6 months now. The lady was hollow and split so bad you can see how many layers of filler i used. Squadron filler white and tamiya putty grey. Squadron putty does not fair well to moisture. I filled the lady full of plaster so the pla (red tr colorfabb) should not split anymore as the trapped air inside is now gone and as it heats in the sun it cant warp as much as it doenst have as much freedom to move as before. So far so good. Last time it split within days of being perfectly rescued. Twice. Third time lucky i guess. Large stuff where acetone gets inside and in direct sunlight and cold temps is very prone to splitting. I think its finally settled now. The arm is glued on, so is the hair, and the hand. But its really solid and properly stuck. I did a great job attaching it if i dont say so myself. As good as a good doctor!! The models that split were all black pla and burger kitty was the light brown. Slight splitting on that one. All models are hollow apart from the lady and painted face. Again did the primer aid the cracking???

 

Dutch orange colorfabb pla pha cracked when hollow and acetone reached inside.

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Black colorfabb pla pha hollow primed with thinned tamita grey primer.

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Red colorfabb tr primed with valejo mecha black. Hollow not capped.

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Light brown pla pha colorfabb (discontinued) hollow primer. Tiny splits

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Black colourfabb pla pha primed with thinned tamiya primer. Filled solid with plaster.

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Eithet the black or paint thinner paint mix or both has split the models. And of course repeated direct sunlight heat and cold exposure Regardless of plaster filling. The lady split due to acetone abuse! Lol. My bad, im a bad influence!

Edited by cloakfiend

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Posted · Acetone Finishing on PLA

I kind of like the worn-out look of the first lady. Looks a bit like a corroded ancient statue that is in restoration, after being discovered in an old castle. Maybe you could keep it this way? Just fill and sand the splits, but no painting?

 

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Posted · Acetone Finishing on PLA

I kinda like the grey bits. But i dont like other bits. It looks like that purely due to the many layers of tamiya filler over time. And the filler itself is drying out hence looking different colours. Its a ton of sanding work which i dont mindcso much anymore but my quest to smooth finishes means im for ever correcting areas here and there resulting in those weird patterns. It was perfect and entirely white just a few months ago. And looked similar back then when i painted it. If you are after that look its not hard to acheive just takes time because you constantlyhave to wait for the previous layers to dry....and thats the most irritating part. I found a quick setting putty (for drains) which sets in minutes but nothing as fine and smooth as tamiya. If you have subtle splits in your model I would highly reccomend it. They doa white one I think a well for extra fine but ive not tried it the grey is fine to me. Also for those new to sanding and watching all those videos showing people going through like 10 grades of grit before acheiving a smooth surface, its not neccesary with pla after acetoning. I use 2 max maybe 3 if its real ruff. 120 for the rough spots if you got any. If just small bumps, 240 will be fine pre acetoning otherwise a bit of a once over with 400 is fine (more than enough for most if your gonna be painting!). But you need to make sure the acetone has dried out or else your gonna have a hard time sanding acetone soaked pla/pha. Its weird in that soft state. But more flexible. After it dries moisturise it if you are worried about it drying out and when it absorbs the moisture and is touch dry then treat it as normal pla again. Paint it sand it whatever.

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Posted · Acetone Finishing on PLA
3 hours ago, cloakfiend said:

Its a ton of sanding work which i dont mind so much anymore

You know you have reached zen-expert status when you start to actually enjoy menial work like sanding. 🥰  

 

I know some guys who grind telescope mirrors as a hobby and they just LOVE sliding two pieces of glass across each other to make a nice telescope mirror.  It puts them in a calm state. 

 

Some people like to sit in the sauna or go fishing.  Other's get a similar satisfaction from sanding their 3d prints.  🙂

 

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Posted (edited) · Acetone Finishing on PLA

Yes, lol, sanding is fine, but waiting for newly applied filler is a real ball-ache. I just got into the habit of sanding before acetoning because it saves so much time in post. I can simply give a model a once over in a few minutes with 240 grit a brush on acetone job and done! The art of sanding is to leave as little to sand as possible. When you slap filler on or have like massive areas to smooth just use a burr tool on a dremmel. They are my new best friend. I have loads and they are cheap as chips and last ages. From 1mm delicate ones to massive fat ones. the smaller the burr the more likely to melt and make smoothing possible. Theres an art to using them. And tons of different shapes for those impissible to sand areas! They will save you hours of time!! Dont even waste youre time trying to hand sand out huge uneven areas!

 

Im now working on something really amazing for my models, but as usual i'm completely new to it and it involves tons of crazy sounding chemicals ive never heard of and powder coatings and....electricity!!! Expensive mind you! Im getting help from some scientists on this one!! Lol. I'm gonna need it, just not enough info on google atm!

Edited by cloakfiend

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Posted · Acetone Finishing on PLA

One of the best tip from cloakfiend is the use of acetone to smooth PLA. I am following this technique on all my 3d prints and the result is amazing!

 

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Posted · Acetone Finishing on PLA

thanks @kris2020. Happy to help! Lots more to come...

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Posted · Acetone Finishing on PLA

Well I finally got round to painting, but as i thought. The warped splits are still visible after painting. Im gonna have to sand n fill and sand for like the 5th time. Im gonna only focus on the worst areas as I just wanna finish it. I could have saved myself the trouble had i just printef it again. This model has a glued arm and hand but holds firm. I plan on glossing it up and using gold leaf for the hair. Done. Also painted the hello kitty, lol.

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Posted · Acetone Finishing on PLA

I like the girl model.

 

Have you ever tried painting such models in a gentle sort of "marble" technique? So it looks like stone or marble? I think that might work for this girl, and it might conceal layer lines and defects. I once knew an artiste who turned lightweight wooden crates into "heavyweight marble" bases for displaying sculptures. These bases were hard to distinguish from real marble. But I don't know how she did it, I only saw the results, not while applying it. Might be worth trying that?

 

I also like the "old" look of the partially painted and sanded model. Maybe that would also be an option: paint multiple layers in slightly different shades of grey, and then sand off a couple of them? That too would help conceal printing-lines, in the way military camouflage hides the shape of vehicles or aircraft.

 

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Posted · Acetone Finishing on PLA

The issue is not layer lines so much (even though the zscrew was dirty when i printed this hence the bad layers), its more heat warped splits. They warp the the plastic outwards at the crack. Like a volcano. So the area to be fixed is like 20 times the width of a crack..... i also did your heat curing acetone by slapping acetone on some objects and popong them in front of a 30degrees fireplace and then directly above it. To interesting results. The acetone may have evaporated which makes to model sandable but the vapours or air trapped inside superheats and results in it becoming extremely soft and bendy. Also the flat base of a hollow object almost instantly starts expanding out. Interesting results. Not sure if it will split later. Who knows!

 

https://youtu.be/FNOnrXe1O4w

 

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Posted · Acetone Finishing on PLA

Also just a note but you only really need two shades of grey to get that weird effect. Here it was the tamiya putty and tamiya primer combo which worked nicely. Maybe ill just try doing a whole model like that?

Im now using lockdown time to try and finish off a bunch of models. Never thought id see a pandemic in my lifetime.

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Posted (edited) · Acetone Finishing on PLA

Here we go again lol. This is my last time fixing it. Whatever it is after it will remain. I should have stuck to tamiya rattle can primer. It dries rock solid and sand well. This valejo mecha white primer is a tad rubbery when dry and hence sands awfully. I slapped on one more coat of tamiya putty to fill the sanded holes. Ill leave it overnight to set hard and sand paint and move on to the next model. I really enyoyed sculpting this one. I may print the full version another time as I did the complete body.

 

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Edited by cloakfiend

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Posted · Acetone Finishing on PLA

I tried sanding a few areas on the face after attempting to fill a few cracks with putty. Turns out this primer doesnt sand well and just peels horribly when combined with putty and i was lazy and tried too soon. Just ended up using acetone to 'wash' everything off. Im slowly getting tired of this.. lol. I now regret not just printing another! Eitherway I've learnt a lot on the way! I guess it pays in the long run to get everything perfect before painting. I just got impatient as usual. Lol.

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Posted · Acetone Finishing on PLA

She looks like sun-burnt now.  :-)

 

I was thinking, for simple models you could make an inverse as mould, and pour gypsum into it. Gypsum is a lot easier to sand than plastic, and its stone-like structure hides small defects and layer lines. Then you would have a solid heavy-weight gypsum girl. But that method won't work for this model, because she has way too much undercuts in the hair, and in her fine hands and arms: even with a complex multi-part mould, it wouldn't go.

 

 

PS: I didn't do any "heat-acetoning" myself. I had considered it, but I didn't want to explode, so I dropped the idea.  :-)  But I have seen quite a few Youtube videos of it.

 

However, I did both "acetoning" and "heat-treatment", but separately and on different models.

 

For heat-treatment I tried annealing (60...80°C) in a lab-oven, to remove stresses and to increase temperature resistance. But this does not work well for me: the models did shrink in length and expanded in width and height, so they didn't fit anymore. It might work for art though, not sure. If you could get the stresses out from the printing and uneven cooling, it is less likely to split. The heating and cooling should be done *very slowly*, so everything has time to settle. If you don't have a computer-controlled oven, I think it is best to do this on a manually heated build-plate in the printer, and cover front and top with plastic. Or put a little box over the model.

 

I also tried a heat gun to smooth, because this did work well on vacuum thermoformed models in the past (it was the officially recommended method). But this does *not at all* work on 3D-prints: it melts the outer layer (as desired), but it also heats up the entrapped air bubbles, so they explode and cause little craters on the surface. Making it much worse than before. Similar to printing wet nylon, but even more ugly. And it causes brown burnt spots. So I don' do heat-treatment anymore.

 

For smoothing I tried dipping testmodels into acetone for some time, but this caused huge cracks, even diagonally through layers (not following the lines), and weakens the plastic and basically destroys it.

 

So the only smoothing method that I use now and that works very well, is yours: brushing-on acetone. And then I wipe it with paper tissue to remove the whiteness, before it is completely dry. Then I can get off most of the white residu. Sometimes I do a second brush, but that doesn't seem to improve smoothness very much anymore.

 

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Posted · Acetone Finishing on PLA

Adding heat to an acetoned model does nothing but heat it up making it flexible by superheating the trapped air and by simply being acetoned. The acetone alters the state of pla to something else and hardens later irrespective of heat. Someone mentioned dishwasher liquid to stop the reaction but seeing as the acetone has already penetrated deep into the acetone i think theres little chance of that as dishwasher liquid does not penetrate pla. 

I must stress to all those new to this thread that this was a completely failed model with multiple reprinted areas and im simply continuing with it as i continue to experiment with various paints and primers. Ill stick to tamiya for light primer i think. Far more durable than vallejo, but their mecha black is fine.

Also i ran out of nitrile gloves recently surprise surprise, but temporarily got powder coated ones. And they suck. They react to the tamiya putty and cause the putty to melt making it much harder if not impossible to apply with a finger. Cant wait for my regular blues to arrive! Im going to do another acetone video soon.... this thread has many broken links as the accounts i used historically have expired.

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