Concrete Batman Bust- Easy Peasy

Hello Batman fans!! I made this concrete cast of batman using 3d printed mold. To cast it yourself, you dont need to print complex molds or formulate impossible mold release, simply print a hollow single layer shell to work as one time mold. You can use same method with any shape of your choice.

Excuse me for the rough surface finish, It is my first cast so still experimenting. I will update this Instuctable accordingly, right now sharing the basic casting method as i was excited by the result and to not miss the Concrete contest.

Checkout my other easy-peasy Shark decor from reclaimed wood Instructable for beginners:

https://www.instructables.com/id/Shark-From-Reclaimed-Wood/

3d printer or 3d printed model

pre-mix concrete or mix your own recepie

Black concrete color

sand

I have used this awesome 3d model by Eastman3d. He makes really cool and easy to print Superhero Busts.

https://www.thingiverse.com/thing:4543753

Used Cura 4.6.1 to slice the model and printed it using Ender 3 and PLA. My slicer profile is mainly CHEP magic 0.12 with following modifications

Specialmode: Surface

Bottom layer: 0

Support: Enabled

Support: Everywhere

Support Overhang angle: 60

Main idea is to print a single skin(wall) model with 0% infill and no bottom. Don't worry about support as you don't have to remove them.

This particular 3d model is friendly to print with such setting. I only got small gaps around shoulder and on head which were easy to fix. So if you want to cast something else check if it is print friendly. You can go with more than one wall but it will be difficult to break later-on, small percentage of infill can also work as it will become part of concrete.

I used clay to fix the holes at shoulder and on the head.

Make sure that it is smooth on the inside as we only care about inside of batman.

Let it dry

Single skin 3d prints are not watertight, sealing the surface will reduce post processing.

I used single coat of Rust-Oleum top coat but you can use anything like spray paint, acrylic wall putty, varnish etc

As the 3d print is only single skin it can't withstand the weight of concrete( i learnt it hard way) so you need to support the structure from outside. For this reason i buried the print in sand, upside down.

I used Sika Grout 214 pre mix concrete. Why pre-mix? Pre-mix concrete comes with added Admixture which allow concrete to be easily poured without addition of much water. If you mix your own concrete than use water reducing admixtures(called Plasticizer or super-plasticizer). Some premix like mine have larger aggregate particles which you can easily be removed by a sieve.

I added 10% w/w concrete black color.

Measure the water as per mixing instructions. Slowly added concrete to the water while stirring. Mix well and tap the container for about a minute to release as many air bubbles as possible. Pour slowly to allow air to escape. After pouring tap the mold to release air bubbles.

I over poured the mold as i wanted a 'Freely-floating' look for my final cast but if you want a flat bottom surface than level it using something flat.

Allow the casting to sit undisturbed for at-least 24 hours. After that use a knife to cut the plastic to reveal the casting. Be careful with weak points like horns and nose.

Concrete need moist environment to cure properly and it will take atleast 7 days to cure. Best is to submerge the cast is slightly acidic water for 7days but it may be a bit overkill, simply wrapping in plastic to lock moisture is sufficient. Do not rush to finish the surface as even after 24 hour of casting concrete may not be hard enough and you will end up ruining the surface as i did.

Now i am waiting for Batman to cure properly before i will wet-sand it and seal the surface with Sodium Silicate.

I will share my results here as tips and in comments.

Feel free to share your doubts and let me know how you liked it!

Have fun!!