Articles, Blog

Finish your filament prints with SLA resin – fast and cheap!

December 30, 2019

I have some filament, I have some resin. Uh. Filament resin! Good luck getting that song out of your head
now! Today I’ll try to combine some of the advantages
from filament printing, that is cheap, fast and can do large prints with the surface finish
of actual SLA resin. Let’s try it out! Just a quick note, we’re working with resin
today, make sure you’re also wearing gloves and appropriate safety gear. I mean, not when you’re watching this video,
but if you decide to try this out for yourself. Before I even started with the actual experiment,
I did a quick test to see whether it was actually worth making a whole video on resin finish
and oh boy, did this have promise. There were two small issues with this trial
where I just literally dunked the part into the resin VAT on the SL1, and that’s that
there is this massive elephant foot from where the resin piled up on the bottom of my container,
and obviously this is neither pretty nor practical, but if you look at the branch structure in
here, many of the branches have also fused into a big blob. I think that’s because the resin itself
is actually quite thick and has a fairly high surface tension, so it likes to round out
inside edges. I did give it quick spray of grey primer,
just to show the actual surface of the part, and the actual effect I was looking for, that
is hiding the layer lines, that’s actually working out really well. So to get started on the first part, what
I did was to thread a pair of screws into the bolt holes on the part and then I stuck
it onto the container using a pair of small magnets, so now we have a gap where hopefully
the resin can just drip off and not leave that big foot anymore. On that first trial, I just had way too much
resin on the part that I then had to get off somehow. So this time, I brushed on some resin, tried
to get it into all the nooks and crannies, but because this was still quite a layer that
I had just put on, I then used a hot air reflow station, which is basically a precise, adjustable
heat gun, and just lightly heated up and basically blew off as much of the resin as I could. When is resin is warm, it gets a lot more
liquid and all the small bubbles that the brush left also instantly pop. The problem is that the lowest this station
goes is 100°C, so if I left that on my part for too long, it would just melt so I had
to be pretty fast with moving it across. Once I was happy with that coat, I tried to
get as much of the resin to drip off and I chucked it into the CW1 to harden the coat. That’s the nice thing with this UV resin,
you can work it as long as you want, it doesn’t “dry” by itself, but once you’re happy
with how it looks, you just pop it under UV light and it hardens pretty quickly. As it turns out, the heated resin actually
gets pretty liquid and leaves layer lines fairly well visible, so I added two more coats
on top and always popped it back into the CW1 for a cure cycle between coats. What I’m definitely still seeing is that
we’re losing quite a few details, some of these branches are starting to disappear and
inside corners are getting rounded out a lot. With the hot air reflow statiom, it’s heating
up the already thin layers at the surface pretty quickly, but the pools on inside corners
and the areas around details have more mass and more of the base part contacting it, so
they’re taking longer to heat up and become liquid. So open surfaces had most of the resin running
off, but in the inside corners it still accumulated quite a lot. When I went to clean up that first part, I
accidentally dripped some isopropanol into my resin container and that gave me the idea
to actually thin down the resin before applying it. With just a thin layer of diluted resin, the
solvent should evaporate off fairly quickly, and if not, I can always help it along with
the “drying” feature in the CW1 or some warm air, but the extra runniness at the start
should be enough to get it out of inside corners quickly – plus, we have the exact inverse
of what we saw with heat. Because inside corners have less surface area
and more mass in the resin pool, the solvent should actually evaporate more slowly in corners
and keep the resin runny for longer. I started out with a mix of roughly 2 parts
of resin and one part solvent, and this immediately made the resin a lot thinner. I mean, as expected. In fact, I could straight up pour the mix
over my part and all I had to do was to make sure it got into all the creases and I could
then have it drip off into my container. A few more coats and cure cycles here, too,
and actually, I do really like how this turned out. It’s covering up all the layer lines, but
still retains a lot of details. Also, this was so much easier to apply – just
pour it over or brush it on as thick as you want and you can then just let the excess
drip off. And the surface finish is actually better
than when I was using just pure resin, if you look closely, you can see some wrinkles
in here, but I think these come from not having an underlying layer of resin fully, totally
cured yet before applying the next one. And since the thinned down resin worked so
well, why not keep going? This time, I mixed up more of a 1 to 1 or
2 to 1 mix – that is two parts solvent, one part resin. This stuff is suuuper runny, definitely much
closer to pure isopropanol than to resin, and I did the same thing – pour it over, drip
it off, cure it. It’s weird, because the surface almost instantly
turned super smooth and glossy on the first coat, even though this mix is a lot thinner
now. One more thing we can see with the super thinned
down resin is that the areas where there was more resin pooled up turned cloudy white. That’s probably because I didn’t let the
IPA evaporate enough before hitting it with UV light to cure it. My favorite one of these three, four, is the
mildly thinned down one, but I did enjoy how easy it was to apply the super thinned down
one. It’s really about time – if you use thinned
down resin, you need to factor in the drying time between coats, on top of the curing time
itself. If you’re finishing several parts at the
same time and coat one while the other one is drying and curing, that’s totally fine,
but if it’s just one part it makes for quite a bit of awkward standing around, because
obviously you’re wearing contaminated gloves and probably don’t want to take them off
and throw them out between coats, but it’s still a bit too long to just stand there and
wait for the curing to finish. Still, it’s a lot quicker than either spraying
and sanding a finish or mixing up a 2 part resin, applying it, and waiting for it to cure. I’m using Wanhao resin for this one, because
I’m thinking I’ll need quite a bit of it and this Wanhao stuff actually doesn’t
harden properly when I use it in a printer, so why not use it up in experiments like this. This is supposed to be yellow resin, but I
think the pigments have settled into a crust at the bottom of the container, so the resin
looks more like, i don’t know, liquid snot or something. But the consistency is pretty much perfect
for this alien egg, I want this to look slimy and wet and disgusting, and a thick layer
of resin is absolutely going to help with that. So, lets glob some of this stuff on. I started with the top, petals, I guess, those
still had some holes in them from the print, and the resin covered most of them instantly. A quick flash of UV light and…. what? What’s that smoke? Well, turns out if you harden the resin too
quickly it actually overheats and cooks itself, and it looks like it also detached from the
print a bit. But it did harden almost instantly! This means I can go right ahead and apply
the next layer of resin. I went ahead and did about two coats on the
entire thing, some areas got a bit more, some a bit less, it’s just hard to cover everything
evenly in basically clear resin, but if you look at how this thing turned out – wow. The surface is really smooth, and with the
thicker, high-gloss resin on it, it really does look like it’s covered in slime. Which, actually, it was. The Wanhao resin still didn’t cure properly,
so it was left with an oily layer on top – either that’s totally uncured resin or it’s some
component of the resin accumulating on the surface, either way it’s not great, so I
gave the entire thing a wash in IPA, which took off most of the sticky layer – at least
enough to apply the final surface finish on top. That’s going to be a gloss coat. I thought about giving it an opaque coat first,
but that would lose that depth of the resin layer and just give it a flat, even color. So just the clearcoat, let’s do that right
now and then let’s compare my results to what it would look like if I just used the
resin as intended, and, you know, just printed the parts directly from resin. So that’s what that looks like. Obviously the resin print still has a lot
more detail, I printed this one at 0.035mm layer height, that took a while to finish,
but it doesn’t quit have the same glossy surface. I guess you could still spraypaint the resin
print and get that, but unless you have a crazy massive resin printer, you’re not
going to get something this size. These brackets are normally over 3 times the
size, and I think at that scale, losing a bit of detail isn’t much of a problem at
all, unless you’ve got a part that does some mechanical job, but while resin coating
you can always mask off surfaces that need to mate with other parts. I definitely like this resin coating approach
a lot and I think this is finally a good and quick way to get rid of print layers. I’ve experimented with nitrous filler, spray
filler, 2 component bog, and a bunch of other approaches, but this one is by far the least
effort, and in comparison isn’t even that messy. And if you still want to do more, unlike PLA
cured resin actually sands pretty well. Let me know if you try this and if you have
any tips to share, leave them in the comments below. And a big thank you to everyone who has already
subscribed, we’re really close to 2 to the power of 18 subscribers, so click that button,
choose your notification level, and I will see you in the next one.


  • Reply Thomas Sanladerer December 21, 2019 at 6:01 pm

    Apparently none of you have ever heard PPAP smh

  • Reply Drauggen December 22, 2019 at 12:25 am

    Can you put the thinned resins in a gravity fed air brush?

  • Reply someoldguy22 December 22, 2019 at 1:01 am

    Thanks, but not going to do this. Seems more expensive, more toxic, and gives no better results.

  • Reply malloott December 22, 2019 at 1:02 am

    How is this different from just adding a layer of epoxy?

  • Reply Marek Fiferna December 22, 2019 at 1:04 am

    With that intro, you've managed to weaponize cringe. Good job, now I'm dead.

  • Reply |Fresh|Pe December 22, 2019 at 1:13 am

    11:11 why is your spray can in a glas of water?

  • Reply Ronny Julian December 22, 2019 at 1:39 am

    Ever tried Total Boat epoxy? I may try both and see what works.

  • Reply ZZooKeeper December 22, 2019 at 2:05 am

    Where do I get that sweatshirt?

  • Reply Dieter Manero December 22, 2019 at 2:23 am

    if you looking to get the shine to your part why not just use wood varnish. turns out just as well.

  • Reply Axel Hopfinger December 22, 2019 at 2:39 am

    I have had very good results with applying one or two thin coats of a clear acrylic-polyurethane floor varnish, especially on figurine prints with sub 0.1mm layer heights.
    The stuff is water thinnable and forms a very thin, smooth and uniform tough coat, whilst filling in layer lines well due to its low viscosity (which is variable with thinning). Also makes little to no mess, no odour and no haste in using it, as it is air drying. And it is dirt cheap compared to resins (about 6€ for a 1 liter pot).
    The matte and satin variants both give a pretty good basecoat for painting. Only problem is, that it will also fill in very fine lines and details if not used carefully, so applying it selectively to surfaces usually gives the best results.
    Epoxy resin is incredibly messy and difficult to use in comparison.

  • Reply Phil Grossman December 22, 2019 at 2:46 am

    maybe try thinning the resin with alcahol and sparaying in on surface with an airbrush.

  • Reply TheShorterboy December 22, 2019 at 3:08 am

    just use epoxy, it's easier

  • Reply philip coulson December 22, 2019 at 3:09 am

    I wonder if the thinned out resin could be sprayed with a cheap airbrush

  • Reply Spinnetti December 22, 2019 at 3:40 am

    Interesting. Even more interesting is the potential to increase the mechanical strength

  • Reply Gabe Nydick December 22, 2019 at 3:49 am

    I've done it before. Works pretty well.

  • Reply Kevin Willey December 22, 2019 at 5:28 am

    Hey Tom – OUTSTANDING!! FINALLY … something relatively NEW in the 3D printing world community worth sharing!! Excellent job!! Thanks for the tip(s)!!

  • Reply username1445 December 22, 2019 at 5:51 am

    tired it, never got it to stop being sticky even leaving out in the sun all day ><

  • Reply Richard T December 22, 2019 at 6:03 am

    Moral of the story … don’t bother with resin 🙂
    Great vid!

  • Reply StrategyYouDidntKnow December 22, 2019 at 6:27 am

    Could you reinforce with fiber and coats?

  • Reply Bruce December 22, 2019 at 6:36 am


  • Reply David Paul December 22, 2019 at 7:02 am

    Pro tip: if you take off your glasses the layer lines go away. Takes two seconds!

  • Reply Mushious December 22, 2019 at 7:31 am

    I want to upvote for interesting, useful info but, I want to downvote for filament resin song. What do I do?

  • Reply Fred - December 22, 2019 at 9:10 am

    I'm wondering if it can improve layer adhesion… That's something Stephan have to test, after CA and expoxy ;o)

  • Reply Neal Leffler December 22, 2019 at 10:00 am

    What advantage does this have over XTC from SmoothOn? Seems very similar. Both are resins and can be thinned with IPA. The only difference I see is the UV cure as opposed to the two part cure.

  • Reply Spikey DaPikey December 22, 2019 at 10:40 am

    Oooooh, I like this idea!!

  • Reply KiR-3d December 22, 2019 at 10:41 am

    Yeah, the great idea for prop. makers!

  • Reply Mikael December 22, 2019 at 10:52 am

    Once you say "Just a few more layers" it's not fast anymore. :´(

  • Reply Chloe Mcholoe December 22, 2019 at 12:06 pm

    maybe test strength too 😛

  • Reply NuRaLoQi December 22, 2019 at 1:04 pm

    I have used wood filler before, can apply it by finger, and just sand off the irregularity and excess. Works pretty well

  • Reply NobleOfBirth December 22, 2019 at 1:06 pm

    That’s a really nice jumper Thomas, the black and white one. Where did you get it?

  • Reply Rob G December 22, 2019 at 2:57 pm

    Was there any change in mechanical strength in the coated prints?

  • Reply DELTACX10 December 22, 2019 at 3:27 pm

    This may be better for structural parts

  • Reply DELTACX10 December 22, 2019 at 3:33 pm

    If your not looking into the LEDs you will be fine. using those glasses is just overkill, if your worried then use some sunglasses with dark lenses, but it's not needed

  • Reply Excentriciteit, December 22, 2019 at 3:53 pm

    How about applying an UV resistant 'epoxy resin' coating with matte color pigments to blur out the layer lines?

  • Reply Blake Cornforth December 22, 2019 at 4:02 pm

    Why didn’t you try heating up the resin to thin it out before applying?

  • Reply Save or Die December 22, 2019 at 6:14 pm

    Thanks for the info. Great idea.

  • Reply Cassie Joy December 22, 2019 at 6:34 pm

    I’m very excited to try this out . I produce props with 3D printed parts and currently use XTC 3D. The work time is awful for large props and the cure time holds me up for hours- this could be the perfect solution for me . Very excited to try it

  • Reply Jared Zadorozny December 22, 2019 at 6:36 pm

    Seems very similar to the xtc-3d. Which is resin, you mix the two parts like expoxy. Leaves a clear "skin" smoothing the part. Leaves a super gloss finish.

    Personally hated the product, is a pain to apply evenly without it pooling in spot or having hanging drops.

    Also much safe to use if you really wanna go down the resin coating a print route

  • Reply Jared Zadorozny December 22, 2019 at 6:46 pm

    Please note that when sanding resin that the dust it creates is extremely fine and terrible to breath in. Wearing a simple cheap dust mask is HIGHLY RECOMMENDED, ideally an organic filter respirator.

    Resin is fairly safe to handle with proper ppe (gloves and Saftey glasses) but when you are sanding that creates a much more of a health hazard.

  • Reply 2QRh6g1I December 22, 2019 at 6:52 pm

    So PLA+Resin = ABS+Acetone ?

  • Reply B Maniac December 22, 2019 at 7:46 pm

    You can try to spin it “centrifuge”.
    That should remove all excess of resin.

  • Reply Technogen December 22, 2019 at 7:54 pm

    Do you think it would be possible to apply the resin better with say an airbrush? I do not have any resin to experiment with this myself but looks interesting.

  • Reply patprop74 December 22, 2019 at 8:33 pm

    I kinda been doing something like that for years now, but I don't have Sanladerer YouTube money lol i had to go down a cheaper route, I use polyester resin with sun cure uvc2000 catalyst mix. It's more stinky till its cured, however, its dirt cheap and gets the job done.

  • Reply Robert Evans December 22, 2019 at 8:43 pm

    Try no thinning and spin the parts after coating.

  • Reply Gene Jordan December 22, 2019 at 11:31 pm

    The aloevera plant was a nice touch for the alien egg husk.

  • Reply Åsmund Ervik December 22, 2019 at 11:55 pm

    About that "don't wanna take off contaminated gloves and throw them away" comment: yes, you absolutely should. Any way you work, you shouldn't be wearing contaminated gloves for more than a few minutes at a time. The nasty stuff goes right through them after a while.

  • Reply SilenTree 12th December 23, 2019 at 12:18 am

    that opening made me cringe so hard..

  • Reply austin grubbs December 23, 2019 at 1:18 am

    Do you think you could thin it and put it in an airbrush to spray it?

  • Reply Myranda Rose December 23, 2019 at 2:02 am

    With slightly thinned resin, in some sort of airbrush/spray gun… with some sort of controlled pulsed UV light… Could this process be more controlled – like a sort of 3D inkjet? With the right sort of timing on the pulses you could hopefully avoid burning the resin and almost instant dry…

    Just something that occured to my brain while watching

  • Reply Michael Thompson December 23, 2019 at 2:35 am

    I wonder if you could get resin to pass through and air brush?!?!?!

  • Reply Abdullah Al-Dar December 23, 2019 at 5:10 am

    These are some interesting outcomes! Doesn't Smooth-on XTC work better? It's intended for covering up FDM/SLA prints and I'd love to see you try it out.

  • Reply Vikki Thomas December 23, 2019 at 5:16 am

    I'm so glad you did this video – I've been using some Wanhao resin as a top coat on a couple projects that had nothing to do with printing and have been wanting to try it out on PLA prints soon!
    +1 to previous comments regarding the sticky surface layer. In some applications it actually helps new layers stick smoothly to the cured layers below them. Multiple layers also helps keep the flash of heat from building up too much. Other uses of UV resin like casting and manicures use multiple layers mainly so the heat doesn't cause damage. Iso will usually clean the sticky layer right off.
    A good cheap midpoint between the flashlight and the chip is one of the lights used for UV gel manicures. They're plenty bright for the task, have great coverage, and come wired up and ready to go. I got mine off amazon for about $20CAD, but there are plenty of even less expensive ones available.

  • Reply Timon K December 23, 2019 at 5:31 am

    Heat the resin itself? Before applying.

  • Reply Michael Joesten December 23, 2019 at 6:05 am

    This is an amazing idea. A thought I had was, what if you put the 2:1 resin mixture into a spray bottle and left the print outside to cure in the sun? That way, you don't have to constantly fiddle about with the part and brush with the resin. Just a couple sprays with the bottle every so often and let gravity/the sun do all the work

  • Reply Kevin Miedema December 23, 2019 at 6:50 am

    hmm hot resin fumes. whats its boiling point again?

  • Reply MikeMike December 23, 2019 at 6:54 am

    Tom coats prints with resin. Stefan coats prints with glue. Coincidence? I think not. 😉

  • Reply miaowzerz December 23, 2019 at 1:31 pm

    I’m getting my ender 3 tmr for Christmas

  • Reply dragonfistbs December 23, 2019 at 2:05 pm

    what happened to the old style finishing with ABS+acetone or PLA+oven 🙁

  • Reply Árpád Hegedüs December 23, 2019 at 3:42 pm

    applying this technique to a 3dlabprint rc plane would be interesting ?

  • Reply Technivorous 3dprinting December 23, 2019 at 6:18 pm

    Hey Thom I know you probably dont do this kind of thing, but, shot in the dark, do u wanna get in on the 2d printed lightsaber design challenge i just issued to all 3dp youtubers? You dont have to mention me or the challenge in anyway, I just want to see what you got!

  • Reply 3DPrintFarm December 23, 2019 at 9:50 pm

    And with a one video, all the vapor smoothing machines and Smooth-On XTC-3D type products stock dropped to zero! 🙂

  • Reply Valour's Blasters December 24, 2019 at 3:43 am

    I think I would have tried sanding between coats of resin

  • Reply Wa By December 24, 2019 at 9:08 am

    Thank you for all videos and Merry Christmas….

  • Reply ransom bot December 24, 2019 at 1:53 pm

    Should try it with an airbrush and pancake compressor and the flashlight on the side to soft cure it as you go on larger prints.

  • Reply Franco Panigaia December 24, 2019 at 4:28 pm

    resin cant cure when there is too much oxygen. therefore you have to wash off the most external layer when you are done. that's what happens there.

  • Reply cataurus13 December 24, 2019 at 9:16 pm

    you could use a vaporizer to spray the 2:1 iso-thinned-resin
    then hang the print on string and let it rotate slowly while uv-curing it

  • Reply Vladimir Kafka December 25, 2019 at 2:05 am

    What you actually need is a simple nitrocellulose (lacquer) primer surfacer. You don't even need a scale modelling quality brand like Tamiya or Gunze, automotive grade will do – a large can costs like a 1/10 of a resin bottle 😉 Then simply brush it on. You need a slow drying lacquer thinner (add retarder), so the layers self-level nicely. Or, of course, you could airbrush it on if you have an airbrush. First layer rather dry, then flood it. If you have an airbrush, there is actually another trick – for a super glossy finish, mist the surface with pure thinner afterwards – with a bit of patience you can achieve a mirror like surface. No sanding involved, no UV light needed, and even though lacquer doesn't smell like flowers either, I'd prefer it over resin any day. Laminating epoxy, like others suggested, will also do. Actually I think there is like a dozen of better options than resin 😉

  • Reply Midztoyz December 25, 2019 at 2:13 pm

    Have you tried using an inert filler like talc to make the uv resin thicker? It's for filling gap and holes. I wonder if it'll cure. I thought of layering prints with polyester resin. But the exothermic reaction can warp the print. I'll need to do more test on this method

  • Reply Kevin Delaney December 25, 2019 at 2:31 pm

    Those sweaters! ? ? I like that black one.

    Haha I love your mistakes, seriously, it's great to see your mistakes so we don't make them ourselves ?

    There has got to be a more automated way to expedite high-quality finishing. ?

  • Reply mechadense December 25, 2019 at 8:41 pm

    I once tried dissolving polystyrene (from joghurt pots) in gassoline and applying it highly viscose with a brush. That worked really well but took a rather long time to dry.

  • Reply Dmytro Bondarenko December 25, 2019 at 9:13 pm

    try to spray it on using something like airbrush

  • Reply AllanScheSar December 26, 2019 at 9:45 am

    Warum stand deine Sprayflasche in einem Wasserbad?

  • Reply Loren Brandenburg December 26, 2019 at 12:49 pm

    My go to is Xtc-3D. You can thin it out with acetone. It's cheap, cures without UV and works on everything. It also allows for easy sanding for painting

  • Reply Willian Bell December 26, 2019 at 1:11 pm

    Hello I am interested in the process, you could share the exact link of the UV lamp with heatsink and fan that you have acquired (the comments link does not include it).

  • Reply Winston Smith December 26, 2019 at 10:20 pm

    Please do dipped/undipped strength tests at some point in the future. Perhaps the gain isn't just surface smoothness.

  • Reply Marwin Thedja December 27, 2019 at 4:37 am

    Featured @HaD

  • Reply Shawn Gorman December 27, 2019 at 4:06 pm

    You should try some test prints to see how thick a layer you are adding of the resin, and see if adjusting the FDM model to account for that extra thickness makes any difference for this coating method.

  • Reply Zerozsaber December 28, 2019 at 3:30 pm

    Have you tried xtc 3d? If you put that on and wet sand it off, it comes out smooth

  • Reply Esteban Marquez December 29, 2019 at 4:56 pm

    Nice!! Thanks for share

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