WHITE PAPER

Measuring the resin concentration of IPA

The level of resin concentration within isopropyl alcohol (IPA) in the Form Wash and Form Wash L increases gradually as more parts are cleaned in the solvent, reducing the effectiveness of the wash. Measure the concentration of IPA using the hydrometer included with the Form Wash or the solvent monitor in the Form Wash L to determine when to replace IPA.

Danger:

Always consult the safety data sheet (SDS) from the IPA supplier as the primary source of information. IPA is flammable and should be used and stored away from ignition sources. Store small quantities of IPA in appropriately labeled and sealed containers.

Measuring resin concentration with the Form Wash

The hydrometer packaged with the Form Wash measures how saturated with resin the IPA is. Before measuring the resin concentration, ensure the included hydrometer has been properly calibrated.

Hydrometer

The hydrometer packaged with the Form Wash measures the range of specific gravity of 0.716–0.881 for use of IPA. When using TPM, refer to the support article Washing prints with TPM for more information on choosing a suitable hydrometer for TPM.

Tip:

Refer to the support article Receiving and setting up the Form Wash for more information on calibrating the Form Wash hydrometer with IPA.

As the resin concentration of the IPA increases, the weight (F) on the hydrometer floats higher, and the stem and O-ring (A) on the hydrometer rise. When properly calibrated using fresh IPA, the O-ring (A) on the hydrometer should be level with the short wings (E) on the float (B). The hydrometer indicates when the resin concentration of IPA reaches 10–12%.

Warning:

Wear gloves when handling printed parts and surfaces that are contaminated with solvent or liquid resin to prevent skin contact.

To measure the resin concentration of IPA:

Remove the previously calibrated hydrometer from the storage area at the back of the Form Wash.
Turn the Form Wash knob to select Sleep on the display.
Push the knob to confirm. The Form Wash lowers the mount and basket into the wash bucket, and lowers the inner and outer lid.
Manually open the outer lid.
Float the hydrometer in the IPA.
Note the alignment of the O-ring (A) relative to the short wings (E) of the float (B). If the O-ring (A) is higher than the tall wings (D), replace the IPA.

Left: Position of float in fresh IPA.

Right: Position of float in fresh IPA.

Measuring resin concentration with the Form Wash L

A sensor measures the amount of resin dissolved in the solvent, allowing the Form Wash L to determine when the solvent needs to be replaced.

To measure the resin concentration of solvent with the solvent monitor:

If you are currently viewing a submenu on the touchscreen, tap the arrow until you return to the Home screen. The home screen lists your current wash settings and the status of the Form Wash L.
The current solvent type and resin concentration are listed under Solvent.

When to replace IPA

Formlabs recommends replacing IPA when its resin concentration reaches around 10–12%. Testing indicates that parts may start to feel tacky when the IPA’s resin concentration reaches 5–10%. Depending on the sequence, part size, and volume of the wash bucket, up to 200 parts can be washed before the IPA needs to be replaced.

Tip:

To significantly prolong the lifetime of the solvent before replacement, consider implementing a preliminary rinse with a small volume of solvent before inserting printed parts into the Form Wash. Refer to the support article Best practices for washing prints for more information.

Recycling or disposing of used IPA

Refer to the support article Isopropyl alcohol (IPA) for more information about safe disposal of used IPA.

Notice:

Do not pour liquid or partially cured resin into drains or dispose of it with household waste. Do not pour isopropyl alcohol (IPA) that contains dissolved resin into drains or dispose of it with household waste. Safe and appropriate disposal methods of used IPA vary by location.