Base 978

Guide to Base978


Base978 has a density of 680kg/m³ and falls into the high-density category of tooling boards.

High density tooling board is best suited for molds with high levels of small detail, or for higher temperature manufacturing processes. Higher density boards produce smoother post-machining surface finishes and can handle sealer really well, saving lots of prep time.

Material Type and Temperature Performance

Base978 is an Epoxy Tooling Board, structurally it is made from glass microspheres, epoxy resins and other chemical hardeners.

The microscopic structure is uniform, meaning the microspheres are evenly spaced and organised (also referred to as Syntactic) which allows it to be machined to semi-complex geometry while still giving a smooth surface finish.

If your tool requires more complex features like etched scribe lines or holes, this board will handle them well with low risk of chipping or damage.

Base978 manufacturer, Base Materials, state a maximum temperature of 145 Celsius. In our experience it can go comfortably up to temperatures of 120, maybe 125 celsius depending on how many cycles your project requires and the complexity of your geometry.

Thermal Expansion

The thermal expansion for Base978 is 39 10⁶ K¹, this is relatively high by our scoring but very much expected of all epoxy boards. 2

The final mold design will need scaling to ensure that the component is correct geometry when released, we handle this if we are designing your tool. If you are designing your tool yourself you should use our CTE calculator to calculate the scaling factor you need to apply.

Blocking Up

Base978, like all epoxy boards, is easy to block up to create larger tools or bespoke shapes and gives an excellent finish.

Visually you will be able to identify where the blocks join on your tool but this makes no difference to the final surface finish or how the tool performs.


Base978, like pretty much all tooling boards, has been specifically designed to machine safely and neatly.

When the drill-looking bit on the end of a CNC machine (the cutter) mills (cuts) the board the material breaks apart in chips rather than dust, this residual material is referred to as the swarf.

Having it chip down instead of creating fine particles or dust is not only easier to clean up but it’s also much safer for the operators - as the cutter gets hot during the milling process, finer dust becomes a fire hazard. It’s also safer for the technicians running the machines not to risk breathing material dust.

With Plyable it’ll be one of our fantastic partners machining your board for you but we’ve included this summary as information.

Finishing Seal/Release

Base978 needs to be sealed before use, the material is too porous to lay up on without and would result in the resin in your lay up (component) fusing with the resin in the tool sticking the whole lot together.

We use Marbocote20023 as sealer of choice, it’s practically inert (won’t react with anything), easy to apply and fast drying. Marbocote2002 gives a high gloss result saving time having to polish after application.

It works particularly well on Base978 because the tool surface is already hard, due to it being high density, so the Marbocote glides on easily giving a smooth, neat finish on your final part.

If your Base978 tool is sealed, you’ll need to use a release agent - we recommend Marbocote HP7 which is well suited for epoxy boards. This is applied to the surface of the tool before lay up and aids smooth component release at the end of manufacture.

Neither seal nor release agents are applied thickly enough to compromise the geometry of your component.

Care and Storage

Your Base978 mould tool should be cleaned between each use to remove general grime build-up and residual patchy release agent.

You can do this using a mould cleaner - our friends at Marbocote make a very good product for this. Once your tool is clean and dry, you will need to reapply the release agent before laying up again.

If you’re curing at higher temperatures, specifically over 100 Celsius, you might notice that the Base978 changes colour after a couple of cycles.

This is normal and shouldn’t indicate any change in the geometry. Additionally, if you have small detailed features in your tool you may see them begin to brown as they gently singe with each cure.

Another feature of Base978 is that it will change colour (from blue to a mid-light green) and become more brittle with prolonged exposure to UV light. If your tool needs to be stored between uses we would recommend limiting the light exposure to the tool as much as possible.

Get in touch to learn more about the right material choice for your tooling.

  1. BE978 Intermediate Epoxy Tooling Board. Base Materials

  2. Base Materials Tooling Board Chart. Base Materials

  3. Marbocote 2002 Product Summary Sheet. Marbocote