One of the most critical steps in every epoxy resin table project, is constructing a great mold to cast it in. I like to do it two main ways, that are simple enough and both have their merit.
So, what are the ways to make an epoxy resin mold? The first is by using HDPE [High Density Polyethylene] sheets to frame it. The other well-used way is with wood and sheathing tape. Both of these methods have a lot of pros and cons, but either can work great for your next casting mold!
This may seem a little simple at first – and honestly it is. Below, I will outline exactly how to do each of the methods, as well as the advantages and disadvantages.
Using HDPE to Create a Casting Mold
This is a great options for both small and large castings! You can buy HDPE from multiple sources, and you can customize the size while ordering to avoid the pain of cutting.
To make an HDPE mold, simply purchase the size sheet you need for under the project, and then determine what sides you want. If you are planning on screwing this mold together, you want to make sure you purchase thick enough sides to be able to put screws into it. What I like to do (if I have the capability) is to use clamps on all sides of my molds – this allows me to re-use the pieces more times.
What are the advantages of an HDPE casting mold? HDPE is super durable, a lot of cutting boards and similar items are made out of this. This means that you don’t have to worry about breaking. Another great aspect is perfect smoothness and straightness – you decide the size so no cutting and sanding.
What about the disadvantages? Honestly – the biggest one is price. It is a little more expensive than wood and table. This also plays a role if you need to screw it together rather than buying clamps. Screwing into HDPE won’t usually be as forgiving or fixable as wood.
Using Wood and Sheathing Tape
I love this method. It makes me feel a lot more “hands on” and it is just about as easy as the HDPE method.
To make a wood and sheathing tape method, you only need those two things. You want a slab of plywood or similar under your project. Then just pick out boards that work for you. For screwing it together, you can use 2×4’s. For clamping you can get something much thinner and cheaper! For sheathing tape, it may or may not be at the local home improvement store – for that reason and price I recommend just getting one like this. All you need to do is wrap one side of the plywood, and one side of each board in the tape, and then set up your mold the way and size you need.
What are the advantages and disadvantages? Advantage for price on this one. You can reuse and purchase in bulk for less than HDPE.
For disadvantages, this may not always be as smooth. This isn’t a problem since most projects get re-sanded after the epoxy resin pour anyway. It is also a bit more intensive and time-consuming to setup.
How to Waterproof the Epoxy Resin Casting?
By now you may have realize something – the epoxy resin can probably get into the cracks of this mold. While that may be true, there are steps to prevent this very easily.
So, how do we waterproof an epoxy resin casting? First, using clamps or double checking your screws can prevent this. If you’re doing the sheathing tape on wood method, make sure to just slightly go past the edges where the casting mold comes together. If all else fails – use hot glue. That’s right. A simple cheap craft hot glue gun around the inner edges of the mold can water-seal and prevent that incredibly easily (and affordably).
What Other Materials Can I Cast Epoxy Resin In?
Tons of materials resist being bonded to! The above instructions are just my two favorite ways, especially to do it affordably. You can also use melamine, silicone, PVC pipe, Teflon, polyethylene, polypropylene, nylon, or Mylar.
Be careful when choosing what you use to fit your purpose. Use a bowl made from one of those materials if you want a bowl-shaped mold for something like turning. Use a small plastic box for sealing small items and coasters. Don’t be limited to just my two methods.
How Long Does it Take to Cure After Casting Epoxy Resin?
This will depend on the type of epoxy resin and hardener you got. As a general rule of thumb, it will take no less than 24 hours. I believe waiting for most large projects at least 5-7 days to be the safest and surest way that you won’t run into any issues while curing. By 7 days, your epoxy resin will be completely hardened and ready to sand, cut, etc…
Where Can I Buy HDPE Sheets?
You can search on Ebay and Amazon, but one of the cheapest places I’ve found is US Plastics. Just be careful because many places will charge a lot for shipping. Don’t limit yourself to one supplier, find the price and size that works for you and go with that.
Definitely check on my site for my recommended products page, this can help pick out both the best and most affordable materials for doing anything wood/epoxy related.