Resin Casting - Polyurethane vs Polyester Resin

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[@CelsoTS]

I know this is an old video but I would like to thank you for taking the time to create it. It helped me a lot to understand the differences and decide the way to go on my project. Thanks from Brazil.

[@thedarkpower]

Thanks! Glad it was useful :)

[@supranomicon]

Great tips and good advice, been casting for a while and use same techniques, agree with your comments on the differences between polyester and polyurethane

[@thedarkpower]

Thanks very much Neil!

[@FirstLast-tx3yj]

@@thedarkpower I am considering pouring a transparent top to an outdoors table(I don't want to use glass) the problem with resin that it might bend or warp, so I was advised to go with transparent polyurethane pour as it not effected like resin with temperature and being in the sun all day. Is it possible to do with polyurethane and leave it in the sun and do you think it will work?

[@thedarkpower]

​@@FirstLast-tx3yj I've never tried this so I can't really comment I'm afraid. I think most of the clear resin table tops you see online are epoxy.

[@strawdog7704]

great vid, plus it's always nice to hear someone in England buying stuff you can get in England. (as opposed to US vids that only buy from company's that only exist in the US)(never mind shipping prices for two pints)

[@thedarkpower]

Thanks! Yeah vids can sometimes be abit US centric and you're left trying to figure out what the equivalent UK brand is!

[@august3777]

I just got into scratch building and kit bashing less than a week ago after binge-watching a few videos from Adam Savage's Tested channel, and in looking for more inspiration/education, I stumbled on this channel, and I have simply been amazed at the level of talent you display with your mech builds and sculptures that I've seen over the last few nights. This video here, ready explains a lot for me, since I am looking to getting into modeling as well. I've only purchased putty modeling compounds, which is nice for small parts, buy resin casting is something I want to get into in the near future for larger shaped items, such as different parts of pre-made models, so that I'm not having to buy entire kits all the time. So thanks for the video--it educated me a lot--and thanks for suggesting other companies that aren't Smooth-on, as I have looked into their products and was wondering about cheaper alternative. Thanks. Look forward to you next video, as well as many of the others you already have that I still need to watch. Awesome job.

[@thedarkpower]

Hey, thanks very much for watching! I'm glad the video proved useful and yeah, I love tested too ;) Good luck with the future builds!

[@TIMBEAU1962]

Thank you so much my master for sharing the secrets of the material you use! Fabulous!

[@thedarkpower]

Thanks for watching dude, hope you're well.

[@TIMBEAU1962]

The Dark Power yes master, I am fine, live to far from humanity to get infected I hope, so far so good! I hope you to, and thank you again!

[@resinweirdos358]

Resins can cause sensitisations, you really should always wear nitrile gloves and a respirator mask or work in very well ventilated area. I’ve never used polyester resin but I like polyurethane and epoxy resin very much! Great video thank you 😊

[@thedarkpower]

Thanks! Trust me, if you ever try polyester resin you'll definitely need a respirator! ;)

[@resinweirdos358]

I’ve heard it stinks so bad, That’s the reason I’ve never tried it lol

[@MLTharme]

Good points, I use Nitrile gloves all the time when using resin, invested in a respirator mask (hopefully the filter is doing it job)

[@resinweirdos358]

ML Tharme better safe than sorry 😊

[@disband_thebbc5933]

Just for clarification spend the extra money to get a reusable P3/99% respirator and spare filters the disposable ones are shite.

[@creativecomposites6193]

Great info thank you. i use large clear freezer bags for covering my scales:)

[@thedarkpower]

Thanks, ah yes, good idea ;)

[@NIGHTWATCHERUK01]

First great to see a English video... question the polyurethane impact resin how strong is it ? the reason is I'am a bench Locksmith and some lock parts have to be replaced due to ware this would normally be expensive due to machining costs. If i can repair the part and cast it this would save time and extra cost to the customer....win......win....

[@thedarkpower]

Hi. It's quite tough but has a degree of flex, hence the impact resistance. I think it would be too flexible if you're casting lock parts as the pieces would be quite thin.

[@tajiksofyat4344]

Thanks for all your effort

[@thedarkpower]

Thanks for watching.

[@artongashi6206]

Which is best for car bumper

[@appleoneill5135]

Great tutorial, thank you so much.

[@thedarkpower]

Glad it was helpful! 😁

[@tajiksofyat4344]

I have a problem with the polyester resin breaking when it falls on the ground. Is there a solution for that to avoid breaking it?

[@thedarkpower]

It's a brittle substance, so that's just one of it's properties. You can mix it with glass fibre to strengthen it. That generally only works for thinner sections though.

[@timothyjak7818]

Can resins be used to cast durable vehicle headlights?

[@thedarkpower]

No, resin isn't that strong.

[@FvckruSSia-c6m]

DWR plastics is in UK. Do you know of another lower priced brands in the USA?

[@thedarkpower]

I'm not sure, you could try www.youtube.com/@bitymoldsupply

[@user-hf4sh8go4t]

هل يمكننى التواصل معك من فضلك

[@ankitpal8044]

Please help I want pu paint formulation for wood please guide me where I can found it ?? @dark

[@FilamentForge]

just found your channel awesome content is polyurethane resin ok to use with latex moulds

[@thedarkpower]

Thanks! Well with the caveat that I've not tried it myself, yes I think that would be fine - I'd test it before trying it for real though, just to be safe.

[@gazsto]

Brilliant video and very informative, would the Polyurethane be suitable for exterior pieces? I believe it has a very good tensile strength is that correct.

[@thedarkpower]

Thanks. Yeah as long as its not too think it's quite tough. It does sand fairly easily though, and I'm not sure how well it would stand up to repeated exposure to the sun. So I'm not sure if it would be OK for exterior use.

[@gazsto]

@@thedarkpower Thanks and appreciated, yes heard they don't like UV, but the supplier stated if painted they should be fine. Also looked at Xencast P2 and P6 Toughened Polyurethane Resin, they are the company recommending painting the pieces. Do you know what happens if exposed? do they disolour, or break down? needs to maintain its tensile strength. Just want to add, a guy in the US, made a sign with Polyurethane resin logo that he covered with gold leaf gliding, and it gets really hot in that climate, so maybe if it's covered, they should hold up ok, as long as the UV doesn't penetrate the outer layer I suppose. All I can do is test to see!

[@gazsto]

@@thedarkpower Just a quick update, after an exhaustive search and discussion with so many suppliers, you can get an additive for UV protection, that's more for professional production though. The P6 Toughened Polyurethane Resin has a pot life of 6 mins opposed to the P2 that has only 2 minutes. Many modern clear coats are boasting UV protection, and you can get it in a spray can, so I think the best technique is what I referred to earlier. Polyurethane Resin when exposed to UV has a tendency to discoloration that's cloudy and in time then can break down and become brittle, so they need an outer coating to maintain integrity and strength.

[@thedarkpower]

@@gazstoI've not used polyurethane outside, so I simply don't know how it'll fair after an extended period outside, so I can only guess I'm afraid. The UV thing was particular to clear epoxies though as far as I was aware. I've definitely had clear epoxy resins that claim to be UV resistant discolour over time after exposure to sunlight, so I'd be wary of any claims to being UV resistant. I'd say do a test before doing anything too involved. Good luck!

[@gazsto]

@@thedarkpower Thanks and will do some testing to make sure. Got a UV lamp, so might give some samples some extreme exposure for a period.

[@MLTharme]

Good idea with the condiment bottle and cups, I'll have to look into those. I can confirm jewelers scales work great for small casting quantities, I've used mine for a year or so and has made measuring my smaller casting quantities so much easier. Do you use anything to try and prolong your silicone mold life? I used spray wax and talc powder, the talc powder is great for drawing in resin to areas that might trap air but doesn't prolong the mold life by much, but the spray wax helps with the mold life but doesn't seem to give a great finish (unless its the wax release I use?) Cheers for uploading this, it was great to watch.

[@thedarkpower]

Thanks, I'll have to get some jewellers scales then I think! No, I'm not doing anything special with the moulds. The same suppliers I mention also do a low cost silicon. It's not super quality - I wouldn't use it for a run of casts of statues for example, but as it's low cost it's great for one off or low use moulds. So for the small mechanical details I'm casting, I just glued them all to a sheet of plastic and just make a fresh mould when one wears out. As they're small they don't get very hot, so the stress on the mould isn't that great.

[@MLTharme]

@@thedarkpower I have to admit that mold your using did prompt me to think about making a mold for all the parts I plan to use for some kitbashing projects I've got in mind, cheers for that creative nudge :-) I'll check out that silicone and see if it might be any use to me.

[@thedarkpower]

@@MLTharme Yeah I've found having a library of moulds of various mechanical bits really useful. Yes I have a video on pressure casting here actually kzbin.info/www/bejne/iXnMmIJ3qsygmac I know people do convert paint pots to pressure pots (the one I'm using is exactly that I think, but it's been converted by the manufacturer). I'd say that if you know what you're doing then go for it, but if you don't best not to mess with something that could potentially explode ;)

[@MLTharme]

@@thedarkpower Just literally found the very video before you replied, my bad, should have checked before writing lol but thanks for replying :-) Aye, I think once my finances are a little more balanced I'd rather buy one rather than build one anyway, I'm not that great a technical things but if it was something that wasn't too difficult to build I'd consider having a bash.

[@thedarkpower]

@@MLTharme I suspect it's not that hard to do, I just don't trust myself with that sort of thing ;)

[@alpaykasal2902]

Great info, great presentation of the info. thank you!

[@thedarkpower]

Thanks for watching!

[@rossknowles5608]

really nicely done!

[@thedarkpower]

Thanks!

[@Ianart26]

THANK YOU!

[@thedarkpower]

Thanks for watching!

[@paraslohar4809]

Sir I need guide line for pu hot casting for rod and sheet making. Please guide with us

[@nikond90ful1]

Thanks for the video.

[@thedarkpower]

Thanks for watching!

[@smoll.miniatures]

Great vid! I’ve been using smooth on products and was about to purchase the crystal clear variant but saw polyester resins and thought I’d give them a research. Do you know any decently prices for water clear polyurethane resins? Can’t seem to find any at a reasonable price.

[@thedarkpower]

Thanks. I've not used polyurethane clear, but I have noticed it tends to be more expensive. I've had good results with epoxy, polyester isn't that great though. I'm not sure where you are in the world, but these guys have some polyurethane clears. www.mbfg.co.uk/water-clear-casting.html?gclid=Cj0KCQjwoK2mBhDzARIsADGbjeoE7b0Zb_XQ4DPfd7HgWMllRDc0L4nXqXuPHGWg8E5-y2BHe_EzfvoaAlY7EALw_wcB

[@shanmugaraja5775]

Hi sir which resin is good for casting scale motorcycle models

[@thedarkpower]

I'd use polyurethane resin

[@sadhanroy6778]

Hello sir are you know that how i make my plastic part from liquied to hard form please explain. Thank you have a nice day.

[@aspunkyyacker6850]

Hi, very helpful video so maybe you can help me as I am in desperate need of it. I have started to make rings, when inlaying opal I've had issues with bubbles and surface imperfections using CA glues (super glue, also what most people use) although it is hard and durable. I've also used epoxy and UV resins, both of which were far too soft when set, too high in viscosity, yellowed and did not deal well with the heat from sanding and polishing, even going soft enough to warp and I really wasn't being harsh on them. I now have a 10ltr pressure tank and compressor so I'm less worried about bubbles. Can you please recommend a specific type and maybe even a few brands to try? As I've looked everywhere online and can't find a good definitive answer! The requirements for the resin are as follows; • Super thin/ low viscosity- essential • hard set like glass but durable- essential • able to sand and polish with power tools- essential • no yellowing/crystal clear- essential • compatible with pigments- preferable • measure by weight/volume- preferable • little to no shrinkage- preferable • Pot working time; 5 to 15mins non- essential but preferable • Set time;15mins to 2hours- non-essential but preferable. Any help you can offer would be greatly appreciated!

[@thedarkpower]

Hi, well I've only tried two types of clear resin - polyester and epoxy. The polyester degassed itself really well but tended to dry a little tacky and didn't take a polish very well. The epoxy was really good though. It requires pressure casting but it's very tough and can take a sand and polish just fine. I used it to make a clear gear stick handle for a van and it worked great. This is the stuff I used. It might do the trick for your purposes. It does take about 5 hours to set though. It takes a tint just fine too - I've used oil paints and also pigments made for polyester resins. www.cfsnet.co.uk/acatalog/Fast-Cure-Water-Clear-Epoxy-Resin.html There are also clear polyurethane resins, I've not tried them though www.mbfg.co.uk/polycraft-opticast-2000.html

[@aspunkyyacker6850]

@@thedarkpower wow thank you so much for this, very informative! And if it only takes around 5 hours that's even batter. I'll give it a go 😁👍

[@matthewharden2437]

this was very informative. I have one question though. Is there a polyurethane resin that cast slow and is still flexible? I want to roto cast a piece but have it fairly flexible as well. The resin I have hardens way too fast and tends to have many bubbles plus it fills the entire mold which is a huge waste of materials in my opinion.

[@thedarkpower]

Thanks. I've used the slow version of this. There's a degree of flex to the casts www.dwrplastics.com/rotoslush-casting-resin.html I've also used Task 15 from Smooth-on. That was more flexible but I found the casts would deform over time, so it was a little too flexible for my purposes.

[@Krishna-nf5ss]

Hi...Photopolymer comes under which category?

[@thedarkpower]

Hi, I've not heard of photopolymer.

[@enigmavapes9652]

Can you use latex molds with Polyurethane resin? Does it need a release agent?

[@thedarkpower]

Yes that should work fine. I've not tried this myself so I can't say for sure if you'd need a release agent, but I can't imagine it would stick that badly. If in doubt do a small test before pouring your mould.

[@enigmavapes9652]

@@thedarkpower I've been using epoxy resin making skull atty stands but I've now lost two mold even tho I used plenty of release agent 😅 so time to try something else.

[@thedarkpower]

@@enigmavapes9652 Oh dear, sorry to hear that! I know Silicon can be expensive but might be time to give it a go ;)

[@enigmavapes9652]

@@thedarkpower already looked and reckon I'll get a kit and make a mold from what I already have and go from there 👍

[@gazsto6733]

Polyurethane resin is it suitable for exterior projects? great video and very helpful!

[@thedarkpower]

I'm not sure to be honest. It's fairly hard, but can be sanded easily, so I'm not sure how well it would stand up to the elements.

[@gazsto6733]

@@thedarkpower Yeah, I have been given varying opinions and some say no whilst others say it's fine. Suppose all I can do is test a few pieces and see how they do, thanks for your time!

[@thedarkpower]

@@gazsto6733 No problem, good luck with the project!

[@atomicredhead]

I use epoxy resin and I've been looking for a silacone mold for a taper candle, but the only mold I can find is a polyurethane mold. Can I use epoxy resin or casting resin in a poly mold?

[@thedarkpower]

Well as far as I know soft polyurethanes aren't as soft as silicon. I've not seen a polyurethane mould before, but I wonder if you might have trouble demoulding the final piece? Not sure if the epoxy might stick to the mould too perhaps? Sorry, I've not encountered that before, so not 100%

[@lazyac_]

Hello, i want to try Polyurethane 80A shore casting, is that dangerous for health? i'm scared by theses bottles ^^.

[@thedarkpower]

Shore 80A refers to the hardness of the material. Polyurethane seems pretty safe to me - it's less toxic than polyester resin for general use, for example. I use it all the time, but if in doubt read the technical sheet for it.

[@Micky-74-v6f]

Awesome! Have you tried using jesmonite or equivalent brands for your fiberglass mother molds instead? I hate polyester resins/fiberglass smells.

[@thedarkpower]

Thanks! Yeah I got some jesmonite ages back for exactly that reason - I was living in a flat at the time and so couldn't really use polyester due to the smell. I did use the jesmonite a little bit but to be honest it really seemed like plaster with PVA glue in it so it didn't seem that strong.

[@Micky-74-v6f]

@@thedarkpower hi, yeah I ought some plaster polymer from Tiranti and was sceptical. I was commissioned to sculpt a big predator wall plaque and I used the quaxial type fiberglass matting that jesmonite needs, so I made it about 70mm thick or more in places and have to say it was like bullet proof. Reckon I coulda stood on it. I didn't add water though, just neat polymer and plaster. Made a few bases too for some Popeye sculptures I made. About 2cm thick. Worth another experiment? If you see Mixter Art on Facebook page some of my sculpts are on there. 😎. Ps, thanks for the cheaper resin tips.

[@thedarkpower]

Yeah I'll have to have another go with it - I've reinforced plaster moulds with fibreglass before and they've been pretty solid, so I can imagine it being strong. I checked out your page- some cool stuff on there :)

[@Micky-74-v6f]

@@thedarkpower thanks! I've dragged my feet a bit with new content lately but I guess with the lockdown it's a good excuse to create. Also similar problems with polyester as I live in a flat, and the smell lingers for weeks. Would kill for a studio or garden. Keep up the great work! I love it!

[@projectdalekmark]

Im going to pressure cast a 60's movie Dalek beaker in clear polyurethane. The beakers walls are approximately 2mm thick. Can you recomend a good value uk brand of water clear polyurethane?

[@thedarkpower]

I've not used clear polyurethane. www.cfsnet.co.uk/ used to do a water clear epoxy which I've used quite alot, but that seems to have been discontinued. You could try Bentleys www.benam.co.uk/products/plastic/crystal-clear-resin

[@projectdalekmark]

@@thedarkpower thanks for those links. I'll give em' a go!

[@SuperGhazni]

I'm Using unsaturated poly resin as of now, but some small parts are very fragile like fingers, objects like sword, guns are breaking up easily, would you suggest me to use polyurethane resin to avoid this.

[@thedarkpower]

Yes, you can get impact resistant polyurethane resins which are flexible so they're really good for thin parts as they bend rather than snap.

[@mohamedelmasry4452]

Comparing strength ,toughness ,shear resistance and waterproof which resin can handle better ?

[@thedarkpower]

It depends what you want to use it for. I don't think polyurethane is that tough - it's OK for sculptures etc though. If you wanted to use it for costume work, for example, some of the urethanes with a lower shore hardness are great because they'll bend if they take a knock, rather than breaking.

[@laraaitken4698]

Would you say polyester resin would work well to make coasters and a light??

[@thedarkpower]

It's quite brittle so I don't think it would be good for coasters. I'm not sure about a light, it would depend on how it was done. I wouldn't recommend heating it though.

[@aiyushg1769]

if you want to cast a box with thin walls, is this possible?

[@thedarkpower]

In principle but probably not the best or easiest way of making a box.

[@aiyushg1769]

@@thedarkpower Hmm, how do you recommend I create something like this: shop.westerndigital.com/content/dam/store/en-us/assets/products/portable/my-passport/gallery/black/1-2tb/MyPassport-1TB-2TB-Black-Hero.png.wdthumb.1280.1280.jpg

[@aiyushg1769]

As in the case, I was thinking to cast it in two separate pieces? But how should I go around making the cast, I will draw it up in Fusion360 but I was hoping there was some sort of software that would just turn into into a mould - magically.... lol

[@thedarkpower]

I think you might struggle to make something very thin like that - those types of things are usually made from injection moulded plastic. Poured resin is a different process. It's not impossible but you would need to pressure cast it to avoid air bubbles.

[@aiyushg1769]

@@thedarkpower Hmm, I'm not sure if I have access to a pressure casting machine, I know of a vacuum chamber I can use. I'll have to reevaluate. Or just make the walls thicker. Thanks for the rapid response :)

[@vx-rob-xv9808]

Hi,can you use polyurethane resin to make speed bag ball hook swivels? Thanks

[@thedarkpower]

Hi, I've no idea what they are I'm afraid.

[@vx-rob-xv9808]

@@thedarkpower boxing speed bag swivel,its basically a 1" nylon ball bearing with a hook through it then a resin housing for the ball,needs to be very hard and let the ball move easily with no friction for maximum speed and fluidity

[@thedarkpower]

Ah OK, no the resin is relatively soft and can be sanded very easily, so I think that would break pretty quickly.

[@vx-rob-xv9808]

@@thedarkpower which resin would be best to be strong but able to fine sand to be glass like smooth

[@thedarkpower]

Might be worth trying some epoxies perhaps.

[@waxeye6488]

When you say polyurethene do you mean polyurethane?

[@thedarkpower]

Yep that's correct

[@mattmurray778]

Im in the us, s there another name or brand that would be here?

[@thedarkpower]

I'd check out smooth-on

[@tajiksofyat4344]

How can polyester resin be made like plastic?

[@thedarkpower]

You could try using polyurethane instead.

[@seamooncosplay]

Thank you for your video, If I may ask, would you say Polyurethane resin is good to use when hardening pepakura cosplay?

[@thedarkpower]

No probs. Not on it's own. You could use it to laminate glass fibre mesh.

[@ICHIBANDIPPER]

Fantastic video, thank you.

[@thedarkpower]

Thanks for watching! :)

[@catalinhaldan8296]

Awesome video

[@thedarkpower]

Thanks! It's this stuff www.dwrplastics.com/general-purpose-moulding-rubber.html

[@ClipNation]

Hey! Nice video, getting started in the Resin Casting world. Just one quick question, is Polyurethane Resin safe for home use? We don't have a separate work area, if not, is it OK to cast outdoors?

[@thedarkpower]

Polyurethane doesn't have a strong chemical odour and so is easier to use indoors than polyester resin. As long as you take care to make sure it doesn't come into contact with food or food preparation surfaces you should be OK.

[@user-xj8rb5ri4j]

hi so happy to find u! i'm thinking about casting a ball jointed sclupture and it seems that they are usually casted in Polyurethane.......but i can't find it in my country so do you think Polyester Resin would be a good substitute? it should be able to handle some point of pressure caused by ellastics in the doll (for posebility) and it can get really thin in some parts(around 2 millimeters) plz help T^T

[@thedarkpower]

Polyester would be way too brittle for that. And to be honest polyurethane probably wouldn't work too well if the pieces are 2mm thick. You could look into stop motion armatures which are machined steel and so would be strong enough.

[@user-xj8rb5ri4j]

@@thedarkpower thanks but that wouldn't work cause i have sclupted the bjd and the stringing is the only option for jointing system now :( and i have seen people use polyurethane like "popovy sisters" dolls but i can't find the material no matter how much i search like there is only polyurethane used for covering woods and floor ....that cant be used for casting right? sigh what to do TT

[@VampyCrafts]

sooo much useful info. Thanks for making this video!!!

[@thedarkpower]

Thanks! Glad it was useful 😊

[@ashan9869]

is rubber mold suitable for casting pu?

[@thedarkpower]

Yes it is, I use it all the time.

[@kainoctis7724]

Sauce bottles resin, pretty ingenious

[@thedarkpower]

Thanks! Yeah they work well.

[@fragmentlab]

Very helpful. Thanks

[@teguhjati249]

Wow ❤️

[@user-hf4sh8go4t]

اريد التوصل معك❤

[@sparkstron73]

Hi Joe great vid and think I'm ready to dip my toe or 1/6 heads in for the first time. www.dwrplastics.com/black-fast-cast-resin/Fast_Cast_Black_500g.html This is the resin you used right, as the link brings up the rotocast resin? Also for making moulds which shore hardness do you recommend for say a 1/6 head mould? Also need to order some mould release spray I guess.

[@thedarkpower]

Thanks Neil. Yes that's the stuff - you could also use the white or beige versions if you were doing something skin coloured too. Mould rubber is commonly Shore A28 - I use this stuff www.dwrplastics.com/general-purpose-moulding-rubber.html To be honest I rarely use mould release - I only use it if the thing I'm casting is porous in some way.

[@sparkstron73]

@@thedarkpower Cheers yeah beige will do nicely for 1/6 heads thanks for the link will definitely do this soon as it looks like i've got a fair bit of time on my hands. Will post up a vid, take care;)