Tutorial: Platazote and Latex Katana
I’m back from Eastercon and Bristol Alternative Market, and the site has finally moved over to its new server! As celebration, it’s time for another tutorial!
This is the basic technique for making convention safe foam weaponry. It’s based on techniques used by LARPers, so these swords are light, durable and won’t hurt people if you bash them. The exact same technique was used on Seigfried’s sword, just scaled up with a much thicker core and foam.
I’ve never found another tutorial for this on the internet, so here’s hoping it’s helpful! Let’s begin.
- Sword to base your design on
- Retractable cutting knife
- Biro pen
- Contact adhesive (It’s totally a tool)
- Wallpaper scraper for spreading glue
- Several large brushes you don’t care about.
- Organic breather/respirator. You’ll be using some nasty stuff made of cancer. Buy one, it’s only £20.
- Latex gloves to protect your hands from evil
- Clothes you don’t care about.
- 0.5×0.75m Plastazote foam. I used 6mm white, you can buy it from Coscraft.
- Carbon fibre rod, at least 10cm less than the total length of your sword. I use at least 6mm, if the sword is bigger, use a thicker one.
- Around 500ml Liquid latex. I buy in bulk from Tomps
- Black acrylic paint
- Metallic acrylic paint, in this case silver.
- Isoflex clear primer. It’s actually a roofing primer, which happens to be made of evil and cancer, hence the safety gear.
- Pots to decant the Isoflex in.
- Talc Powder
- Silicone furniture polish like pledge.
Set up costs for this can be a bit pricey, but once you get started you can reuse many of the tools and materials.
Katanas have a certain curve to them I don’t trust myself to replicate. So when I’m making a sword I’ll just draw around a handy katana I have around to get a feel for the shape.
This sword had some fancy stuff on it, so I drew that on. Next, lie the carbon fibre rod on the sword to make sure it fits. You need there to be at least 1cm around the edge, or you may get it poking out.
Cut it out using your knife.
Trace it on to another part of the foam
Cut the middle channel for the rod out of the piece of cut foam.
Apply glue to both the traced side and the cut out side. This is my big tub of contact adhesive, I have lots of it. You can also buy this stuff in small tubes, I just buy in bulk.
While waiting for the two pieces to dry, glue a piece of material over the tip of the carbon fibre. This will stop it poking out the top and the core from moving around inside.
Place inside the premade groove and add MOAR glue.
Glue the two sides together. Foam will stretch and move out of shape, so make sure that the top piece lines up with the outline you traced earlier.
Cut it out. This can be quite rough, you’ll cut it to the correct shape in a bit.
Glue both sides, ready to put on another layer
Sandwich it down and then cut it out, making a 3 layer sword.
Using your blade trim the sword so all the edges line up. You can create the curve of the blade by carefully trimming at an angle.
Glue your hilt on
Cut out a rectangle slightly longer than the rod. Coat both sides in glue and let dry.
Roll it like a swiss roll. If you have a flat hilt you can just make it as part of the blade, it’s just for this commission the sword had a specifically round one.
If you use the roll technique, add a top to it.
Now on to painting!
Mix your latex and black acrylic until it’s about this colour. I make my latex up in Tupperware boxes so I can seal the lid on them and keep it fresh for multiple coats.
Paint it, making sure you don’t let the wet sides touch anything. I was quite lucky as this one had a hook in it’s hilt so I could paint the entire thing and hang it on my washing line. If you can’t do this do it in two parts so not to mess up the one side. Many thin coats are better than one crappy thick one.
Oh my camera, what a wonderful view of the sword you gave me.
I use at least 3 layers of latex. You’ll know it’s done when you can’t see the foam texture any more. It will also be completely black.
Paint it using acrylic paints. I dry brush with metallics because I like the aged effect it gives.
You can now leave the sword, though it won’t be particularly durable. If you want that extra bit of security you’ll want to coat it all in isoflex.
WEAR YOUR BREATHER AND GLOVES. THIS STUFF IS BOTH TOXIC AND ANNOYINGLY STICKY. DO THIS OUTSIDE AWAY FROM LIVING CREATURES.
I decant my isoflex into air tight containers before using it. The tins can’t be opened without ruining them, and the insides of the tin will set hard in a week. Splitting it into containers means it lasts much longer, especially as you only need to use a tiny bit each time.
You want to paint it on using a very thin coat so it doesn’t drip. This stuff is incredibly sticky, so paint it in two parts if you have to.
When you’re done painting hang it up to dry outside, put the lids on the isoflex pots (and put them somewhere like a shed where people can’t smell them), then put the brush and gloves directly into your outside bin.
Isoflex takes about a day to dry and then you can touch it. It will feel slightly sticky and weird though. Here’s how you get rid of the sticky feel:
- Cover the entire thing in talc powder until it’s not longer sticky
- Polish it with furniture polish and a cloth to get rid of the white powder.
And here’s the result:
Feel free to ask any questions you have!