When setting any type of project with epoxy, it’s important to know what materials it doesn’t (and does) stick to. Each material has some pros and cons associated with it.
The most popular materials that epoxy resin won’t stick to are:
- Vinyl/Rubber/Silicone
- Wax Paper/Parchment Paper
- Sheathing Tape
- HDPE
- Most Plastic Containers
- Plastic (Sandwich) Bag
- Hot Glue
Although there are doubtlessly more options for non-sticking surfaces for epoxy, this should be a good list to get you started on any project. With all of these there are going to be a few considerations to take into account that will affect how the epoxy cures. Below are the things to take into consideration with each material.
Vinyl/Rubber/Silicone:
Silicone molds are a super popular option among people who make small items such as coasters, jewelry, and uniquely shaped items.
Pros:
These are going to provide you with the opportunity for as many shapes as possible. You can even make your own molds if desired. They are also cost effective, and resistant to heat. Overall I love using molds for special items and smaller pours, they are super efficient, perfectly shaped, and require very little “fixing” after the cure.
Cons:
There are a few of these as well. Most noticeably you will not be able to find a silicone mold for a large item (tables, desks, etc…). Another thing to be aware is to read reviews and look for molds that are shiny. Often molds are for baking or ice trays and don’t have the “gloss” that is necessary to help epoxy remove – you can still use these, but they are likely a one-time use.
Wax Paper/Parchment Paper:
Pros:
Super easy and affordable. This is great for covering under a live edge pour or making an easy mold for a smaller table.
Cons:
This cheap and simple trick has its fallbacks. First, when the epoxy comes off I often notice that it is not as “clear” as the other methods. I think some of the wax gets into it making it (very slightly) foggy. The other is that this doesn’t stay in place as well. It is likely that the wax paper could move during the cure and cause issues.
Sheathing Tape:
Pros:
Pretty affordable and works well. This can also be made to be as large as the product itself. Leaves the shine and allows for a variety of shapes and angles. It is also possible to use this more than once if it is made correctly.
Cons:
Having all the seams means a non-perfect piece, this is okay just know you’ll need to sand and buff after. It is only as flat as the surface you put it on, so be aware of that. Making the form could take a long time for a big mold.
HDPE (High Density Polyethylene):
Pros:
This is going to be a high quality, reusable, and sturdy option. You’ll want to use this for table molds and things similar to that. This is probably the most “high-end” option and is used by a lot of professionals who do river tables. You can order it to the right size and sturdiness for your project. This is also what a lot of cutting boards are made of – if you’re in a pinch.
Cons:
It is the most costly option. It can also take a while to learn what density and size you need, and could take a while to get everything together.
Most Plastic Containers:
This will include things like Tupperware, bowls, plastic cups, etc…
Pros:
Cheap, easy, and around the house. This is great for getting a large bowl together to use for woodturning. It also works for unique shapes and paperweights. If you know what you need and one of these items works, you are in luck.
Cons:
Not at all able to customize. You kind of just get what you get and no more. No large pieces or tables coming from this.
Plastic (Sandwich) Bag:
Pros and Cons:
This is kind of a neat one in a pinch. A regular gallon bag can work, but other than the fact that it does work, there’s really no reason to use it unless you have a specific application.
Hot Glue:
Pros:
This is great for making molds and sealing the cracks. It also is used on top of river tables to prevent too much overflow around the area you pour.
Cons:
You can’t use just this, it is just an addition to other materials to allow you a more perfect item. It is also a little tough to get off rough wood and can leave a small mark.
So what’s the take away?
You really need to evaluate each product individually. Each piece will have a different application. The above list is a great starting place, but check out other articles on exact types of molds or how to make specific pieces – we are full of ideas and free tutorials that are step-by-step!
Don’t forget to take a few other things into account either:
What Temperature Should I Cure Epoxy?
The general consensus is roughly 75 degrees Fahrenheit, although this will depend on the type of epoxy and depth of the pour.
I have cured in rooms as cold as 67 degrees and I have seen it done in areas that get over 97 sometimes. Using fans will help with curing (watch out for dust).
What Factors (Other Than Material) Will Affect My Epoxy Cure?
Temperature, thickness of the pour, dyes used (to an extent), and humidity are big things to take into account.
Make sure you read your particular epoxy label, each manufacturer will have a specific requirement for best results. Just know if you do it right, and it does turn out, you can at least ask for money back (and learn not to use that brand).
How Do I Make An Epoxy Mold?
Silicone molds, wood and sheathing tape, and HDPE molds are going to be the top ways. Each has their own pros and cons but overall these are the most popular.
Unless it is a unique shape, my preferred way is going to be with wood and sheathing tape – this allows for any size plus affordability. It is a good in-between of the silicone (small only) and HDPE (pretty pricey). You can view a post on how to make table molds here:
Will Epoxy Stick To Already Cured Epoxy?
Yes and no. Epoxy will not create a chemical bond with already cured epoxy unless you sand it down first. It can still stick to other epoxy, but it will definitely not be strong enough for a well-created project that will last.
For doing this, just take a sander and run over it with some 220 grit paper, then clean it off well, this will allow for a chemical bond to be made and create a seamless epoxy project.