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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.

 

image.png.9b3832d4b43a9d14d5c98dbed86c525e.png

 

image.thumb.png.fe91b2a7b31fc1a55242fc065103c234.png

 

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!

 

IMG_9134.JPG

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IMG_9125.JPG

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!

20200210_232848.jpg

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.

20200210_233026.jpg

Transparent Red Colorfabb PLA/PHA (NO SPLITS)

20200210_233152.jpg

Ultra Marine Blue Colorfabb PLA/PHA (NO SPLITS)

20200210_232619.jpg

Black Colorfabb PLA/PHA (LOADS OF SPLITS)

20200210_232748.jpg

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.

20200213_200622.jpg

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20200213_200558.jpg

 

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

20200213_200643.jpg

20200213_200651.jpg

20200213_200659.jpg

 

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

20200213_200805.jpg

 

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

20200213_200739.jpg

 

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

20200213_200903.jpg

20200213_200948.jpg

 

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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