A while ago, I did my
first foray into cap craft. Since then, things have evolved considerably and my model have gotten much better. This has not been without a ton of trial and error though and a considerable number of failures and the expenses that go with that. As such, I decided that I'd get a kind of journal up and going in here for anyone who's considering getting into cap craft themselves. Hopefully my knowledge base helps some people save some money and get started into making some interesting artisan caps.
Right now this post is just a rough almost stream of consciousness post, but I'll work on it some more tomorrow and start getting things better organized and start updating with my different experiments/experiences and words of advice. If other people who are experimenting with cap craft want to chime in with their experiences, please do so.
If you have some different dyes or pigments you'd like me to try in my resins, let me know and I'll be glad to take some from you and test it out. Or if you want to donate different resins for me to share my results with, I'll definitely do so as well.
I plan on hitting on the following topics in my little rambling. If there's anything you think I should add, let me know. The topics are as follows:
- Making your master
- Mold materials: What works and what doesn't, best techniques (from my experiments)
- Sprueing and the importance of proper sprue locations
- Experiments in coloring caps
- Resins: What's worked for me, what hasn't, and curing times
Making your masterThere are many ways to make a master for making a cap, but whichever way you go, don't expect the cap to necessarily be reusable.
My preferred method of making a master is with Sculpey.
Sculpey is a pretty easy to work with material that's incredibly cheap. One sub $1 pack of Sculpey should last you for several caps. When I craft caps with it, I generally knead it to get it nice and flexible, mold it onto the cap, then shape it on the cap. From there it's easy to add more or cut some off. Once you have everything prepped, you can either make a mold from the soft Sculpey or dry out the Sculpey.
I prefer to dry mine a little before making a mold. Drying it makes it much easier to remove the master from the mold without destroying it or damaging the mold when you remove any flecks of it that may end up stuck in the mold. You have to be very careful when you dry it though. Sculpey's cure temp is higher than the melt point for ABS plastic, so you can't just stick it in the oven or toaster and let it cure since it will ruin the cap. My preferred way of solving this issue is by using a paint stripper/heat gun and waving it back and forth across the Sculpey to ensure the ABS doesn't get too hot. After a couple minutes, you're good to go. A hairdryer may work as well, but I haven't tried one.
Other people do different methods. I believe
Bro Caps used modelling clay for his master (and ingeniously used ball bearings or BBs for the eyes) and I'm not sure what Binge uses. I think I remember him saying he sealed his with acrylic before making a model of them though. For my original try at cap craft, I actually used wax and did subtractive modelling instead of additive like clay and Sculpey generally are.
Mold MaterialsThe materials that you make your mold out of is important to the final cast. If your mold is too soft, it may not last through many casts. If it's too hard, your caps can be difficult to remove and may damage the finer details of the mold when being removed.
So far, the two mold materials I've played around with are the more readily available Alumilite High Strength 3 (a pink silicone) and Alumilite Quick-Set. Out of those two, I would not recommend the High Strength since it's too soft of a mold that easily breaks. The Quick-Set is better, but can be almost too hard at times.
In the future I plan on trying Smooth-On Oomoo since it's supposed to be one of the best silicone mold materials to use.
When making your mold, ideally you want to degas the silicone. Degassing removes air bubbles from the silicone and ensures that you have a nice, clean mold. In addition to creating defects in the mold that show up in a casting, air bubbles can also give something for the resin to grab onto when curing and pull out portions of your mold when you pull it out.
When I make a mold of a cap, there are four things I like to do. First, I like to put a piece of tape on the bottom of the cap and cut it to size like this:
What this does is ensure that your silicone doesn't seep into the bottom of the cap when you're casting the top. It also makes it much easier to clean up the bottom side of the mold before you pour the top. In this case, the bottom side of the mold generally holds the master for the top side of the cap since I find it's generally best to pour them inverted.
Secondly, spray the piece you're molding with mold release. While not entirely necessary, it makes removing the cap from the mold without damaging it easier.
Third, create some homing nubs in the mold so the two halves line up properly when casting. You can do this by placing several dome shaped somethings in the bottom of your container that you're pouring your mold in or by cutting them into the bottom half of the mold after it's done curing. Either works fine.
Fourthly, I smear the bottom half of the mold liberally with vaseline before pouring the top half. This helps ensure that the two halves of the silicone don't bond to each other. In my experience, mold release alone wasn't enough to do this.
SprueingThis is by far the most important thing to consider when you're making your mold. Without proper sprue locations, you can end up with ruined caps every time. When creating sprue holes, you're creating places for resin overflow to go to and where trapped air can escape.
When choosing your sprue locations, look and see if any part of your mold going to be higher than the sprue hole. If it is, then you either need a sprue hole to that location, or to rethink where your sprues will be located.
In general, your sprues will fall into two categories, sprues included when you cast your mold and sprues cut into your mold.
I'll discuss more about this later, the impact sprues have on your molds, and how sprues can affect the life of your mold if not properly chosen.
ResinsI'll update more on this later, but I will say this now, for most resins, a pressure pot is your friend. Unfortunately, I don't have one yet since I haven't seen one for under $400-500, but I plan on getting one in the future and showing the difference it makes.