Formlabs Castable Wax 40 Resin FAQ

This informative sheet gives you the answers to frequently asked questions about the Castable Wax 40 resin from Formlabs.

Last edited: 1/8/2021

How does this new resin differ from the Formlabs Purple Castable Wax?

The new Blue CW40 has a higher wax content in the resin. This allows you the option to print and cast larger items like championship or class rings, or larger pieces in general. Higher wax content helps with a cleaner burnout.

Comparison chart between Formlabs CW40 and purple casting wax

Is this resin the same as the previous Blue Castable Resin from Formlabs?

No Blue CW40 is a new formulation. The Blue Castable Resin previously used by Formlabs is in the process of being phased out.

What resolution can it print at on the Form 3?

You will have 25 micron and 50 micron settings available with the Blue CW40. Further resolution updates may be supplied with newer versions of the Preform software.

Does it print differently?

Not at all. No post curing is required, and the cleaning process remains the same. Clean with 91% isopropyl alcohol or higher until no liquid resin remains on the surface, and the piece does not feel tacky. Soaking, ultrasonic, or the Form Wash are viable methods for cleaning these resins.

Are the surfaces smoother than the Purple Castable Wax?

The surface finish is comparable to the Purple Castable Wax.

Will the Purple Castable Wax be phased out for Blue CW40?

There are no plans for that currently.

Which Castable Wax should I use, the Blue CW40 or the Purple Castable Wax?

The Purple Castable Wax is best suited for pieces with very small details. Things like very small filigree. The Blue CW40 is best for medium to very thick pieces, things like engagement, bridal, class rings, championship rings, or other items of medium to larger sized cross-sections.

Does it require anything special to print?

The Blue CW40 does require the new Resin Tank V2.1 to effectively print on the Form 3. CW40 can be used on standard Form 3 Resin Tanks, but quality or consistency can be affected.

Are print times different?

Print times for the Blue CW40 are comparable to the Formlabs Purple Castable Wax.

Are the supports different than the Purple Castable Wax?

On average, the supports for printing with the Blue CW40 will be slightly thicker. This is due to the fact that the CW40 is a much softer material that is used to print larger items. Preform will provide recommendations on support thickness when you are setting up your model for printing.

Post-Purchase Guide

Supporting: Preform will provide recommended support thicknesses and touchpoint sizes in the software. Going outside these recommended parameters are up to the user’s discretion.

Support Removal: A pair of cutters is recommended for removing the supports. Clip off the support with a very small amount protruding from the surface, and then file smooth. Standard files can be used for smoothing. Clipping off the support with a small amount left on the surface makes sure there will not be a divot from simply pulling off the supports.

Cleaning: Formlabs recommends cleaning the print in 91% isopropyl alcohol or higher, up to 99%. Soaking in alcohol, ultrasonic in alcohol for 2-3 minutes, or using the Form Wash for around 20-30 minutes will adequately clean the print for casting. All previous methods are viable. You want all liquid resin removed from the surface prior to investing and casting. No shiny surfaces, no tackiness on the print.

Curing: The Blue CW40 does not require any post curing. Any experimentation in curing the CW40 is up to the user’s discretion.

Investing: We recommend using R&R Plasticast Investment mixed at a 38/100 ratio. This investment is specially formulated for casting resins. We have a PDF document on the Rio product page with instructions on how to calculate the appropriate amounts of water and investment powder. Use of any other investment is up to the user’s discretion, but we cannot comment on recommended burnouts for those investments. Examples include R&R Ultravest or FOV Caster’s Blend. This will be up to the user to test.

Burnout: Here is our recommended burnout schedule.

  • 300°/hr ramp to 300°F – Hold 4hrs
  • 550°/hr ramp to 700°F – Hold 3hrs
  • 550°/hr ramp to 1400°F – Hold 4hrs
Full ramp to casting temperature – Thicker models require lower flask temperatures (850-950°F), while smaller, more delicate models require higher flask temperatures (950-1050°F)

Casting: Vacuum Casting, Spin casting, or Induction casting can be used.