Resin wash stations: comparing baskets and usable capacity

Bucket liters are not usable capacity

Wash station product pages like to lead with a liquid volume in liters. That number describes how much solvent the bucket holds. It says nothing about which part fits in the basket or how high the inner lid travels when the cycle ends. To compare two stations you need three separate pieces of information: the usable envelope in length, width and height, the loading configuration that envelope applies to, and the margin against overflow.

According to the Formlabs guide on washing prints, larger parts may not fit in certain orientations or may cause the wash bucket to overflow. That is why the company publishes maximum part dimensions for each Form Wash generation rather than a single bath volume. This is the kind of data you should ask for from any wash station, including brands this page does not cover.

This page deliberately stays within the models Formlabs documents. The values below do not transfer to other manufacturers' stations. Before buying, place the station inside your startup budget and check that your resin post-processing steps match the size and geometry of the parts you actually print.

Documented envelopes by Form Wash generation

Formlabs documentation separates three machines. The first-generation Form Wash accepts parts up to 14.5 × 14.5 × 17.5 cm, and the guide does not split that figure between platform and basket. The second-generation Form Wash widens the footprint to 20.0 × 14.5 cm, with a height that depends on configuration, covered in the next section. The Form Wash L, built for larger formats, reaches 33.5 × 20 × 30 cm.

Between the first two generations, one footprint dimension grows from 14.5 cm to 20.0 cm while the other stays at 14.5 cm. The benefit for a long or tall part depends on orientation and loading configuration. Compare all three dimensions together; a gain on one axis does not guarantee that a particular part fits.

To compare, measure your typical prints in the orientation they come off the printer. The guide notes that large parts may not fit in certain orientations. A part that clears the footprint diagonally can still hit the height limit, and the reverse is also true. Then map each measurement onto the envelope for the configuration you will actually use, not the largest of the three.

On the platform, basket removed, or in the basket: three different heights

These are three distinct loading configurations. The difference between the lowest and highest published heights is 4.5 cm; it may matter for an upright part, but compare the part geometry and basket path for the actual configuration.

Each configuration maps to a workflow choice. Washing on the platform means you do not remove parts before the bath. The Form Wash user guide describes sliding the platform's top lip onto the arms of the platform mount after scraping excess resin back into the tank. Washing in the basket means first removing parts from the platform with the removal tool, scraper or flush cutters. The guide prohibits washing loose parts in the bucket without the basket: it damages parts, creates noise and can interfere with agitation or damage internal components.

When you compare stations, look for whether the manufacturer distinguishes these cases. A single envelope with no configuration stated does not tell you whether the basket and platform can coexist in the machine.

Overflow: enclosed volume matters as much as dimensions

Fitting the envelope is not enough. The Formlabs washing guide stresses solvent displacement: a submerged part raises the bath level, and the bucket can overflow. The company publishes enclosed volume thresholds per machine. On the first-generation Form Wash, the risk starts above 1.8 L. On the second generation, the threshold is 2 L when washing on the build platform and 3 L when washing in the basket. On the Form Wash L, it rises to 7.5 L.

Enclosed volume is the volume the part actually occupies in the liquid, sealed cavities included. A hollow part with no drain holes displaces as much solvent as a solid part with the same outer shape. Formlabs recommends removing some solvent with the siphon pump before washing a print larger than these limits.

For an honest comparison between stations, put the overflow threshold right next to the envelope. One machine may accept a long, flat part dimensionally while staying far below the threshold, while a compact block can fit dimensionally and still overflow. The bucket's liter rating does not give you that margin directly.

Accepted solvents and dedicated buckets per resin

According to the Form Wash user guide, the machine runs on isopropyl alcohol (IPA), tripropylene glycol monomethyl ether (TPM) or Formlabs Resin Washing Solution. Formlabs recommends against water, which can cause rusting. That matters if you are considering a water-washable resin: solvent compatibility with the station is a separate check from compatibility with the resin.

For IPA, the Formlabs guide requires at least 30 minutes of drying after washing, with appropriate ventilation during evaporation. TPM does not evaporate readily and may leave a waxy texture: the guide describes drip drying followed by a water or clean IPA rinse. The second bath and its result depend on the resin; check its instructions. In every case, Formlabs requires parts to be completely dry before placing them in Form Cure.

The documentation also calls for a dedicated bucket with certain resins to avoid color or particle transfer: Castable Wax Resin, Castable Resin, Rigid Resin and Ceramic Resin. If you rotate between several resins, how easily you can swap buckets becomes a comparison criterion as concrete as the envelope. Formlabs adds that third-party solutions are not certified for its biocompatible applications, a point to confirm with the manufacturer for any such use.

Clearance around the station and geometries that cause trouble

The Formlabs pages used here do not list the machine's outer dimensions. They do describe the internal motion: the platform mount and basket raise automatically at the end of the cycle, and solvent dripping onto the inner lid drains back into the bucket. Plan for clearance above the station to allow that travel, and check the height available under a shelf before placing the unit.

Part geometry adds its own constraints. According to the washing guide, long parts that hang outside the basket perimeter can dislodge the inner lid when the basket rises. Very small parts can pass through the basket and impede the impeller. Hollow parts, internal channels and concave surfaces trap solvent or uncured resin, which means spill risk on removal and sometimes a second wash cycle.

Finally, the second generation offers preset wash times of 1, 5, 10 and 20 minutes plus a custom setting, and a high or low impeller speed. Formlabs points to its wash time settings article as the reference for each resin, and suggests adding 5 minutes when the bath carries a high concentration of resin.

Sources and limits

• Best practices for washing prints | Formlabs
• Using the Form Wash | Formlabs

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.