At MakerHero we love seeing awesome use cases for our filaments and when we see something we like we'll always ask to share it! This post written by Cara-Ann Simpson goes through her experience using the MakerHero Rustable Magnetic Iron PLA to an awesome effect for her art exhibition!
I wanted to create some sculptural rocks that connect to the iron-rich red earth where I live for a multisensory exhibition, Furari Flores. It made sense to use MakerHero’s magnetic iron filament, given its chemical similarity to the dirt here. It prints as a lovely dense charcoal grey colour and has a matt finish. I love the weightiness of this filament, alongside its ferromagnetic and oxidisation (rusting) capabilities.
Preparation is key to the best rusting effects. I printed quite thin structures so I couldn’t go too hard with some of my surface preparation. However, I had good results with sanding and sandblasting. If I had more time, I think it would have worked even better. I also trialled a wire brush with some success, but not as quick as sanding/blasting and it left noticeable scratch lines/patterns. Steel wool might be worth a go as well, and it’s something I have on my list to trial.
The reason for sanding/sandblasting is to expose the iron particles in the filament – making them susceptible to rusting. On the first attempt I sprayed my solution onto a print fresh off the printer – and was disappointed in the lack of rust. It does make sense - when the filament is heated and printed the PLA softens and smooths, encapsulating most of the iron particles. So you need to expose the iron particles by roughing the surface, or removing the outer layer (doesn't need to be a lot of material).
I’ve seen other posts about submerging the print into a salt solution – I don’t think this would work well. When I significantly increased the concentration of salt in my solution, I ended up with white crystalline salt lines where it dried. I’m guessing that effect would increase if submerging a print in salty water. Not to mention the downside of having water infiltrate the layers and walls of a print.
The rust solution I used was a mixture of hydrogen peroxide 3%, white cleaning vinegar and table salt. At 3% dilution the hydrogen peroxide is pretty safe to handle, but I still recommend using PPE (gloves, safety glasses and a mask) and decanting it in a well-ventilated space. Check the MSD for more safety info. Hydrogen peroxide 3% is readily available – I bought mine from an online plant maintenance company, along with a misting sprayer. Again, use PPE during the spraying process. As a side safety note, hydrogen peroxide 3% is commonly used as a hair and clothing bleaching agent.
For the solution – I used a 4:1 ratio of hydrogen peroxide 3% to vinegar, and then salt (the salt needs to completely dissolve). For 500mL I used around 2 tablespoons of salt.
I saw my print starting to rust within seconds of spraying it. Using the mister, I sprayed light, misty coats, re-coating a few times and letting the print dry between coats. For this project, I was under some time constraints, so I didn’t push it as far as I could have. Next time I’m going to try an 8:1 ratio (hydrogen peroxide 3% to vinegar) and experiment with the amount of salt.
I haven’t sealed these prints, as I’m happy for them to continue rusting. However, the next time I do something similar, I’ve purchased a high quality automotive UV protective clear matt sealant.
Images by Cara-Ann Simpson, scent sculpture at Furari Flores, UniSQ Art Gallery 2024. Photo: David Martinelli - DC Imaging.