Introduction

After printing, you will need to wash your parts with a solvent to remove any excess uncured resin off the surface. Curing your parts without sufficiently cleaning can lead to dimensional inaccuracy (remaining resin will cure on surface, in cavities or within holes) or tacky surfaces. 

Some good practices when it comes to the washing stage are:

• After a print has completed, let it hang for a few minutes so the parts will drip resin back into the vat. This will limit the amount of solvent saturation.
• You can remove parts on the build plate before washing to limit solvent saturation but keep in mind that it is at higher risk of distortion during curing. 
• Build plates do not have to be cleaned of uncured resin if being immediately used to print with the same resin. If used with another resin, make sure to wash excess resin off with a dirty bath. There should be no visible excess resin afterwards but if the surface remains tacky, that is fine. 
• Build plates should be free of any cured resin (on the surface or within the slots) before being reused. This can cause homing issues or damage your membrane.

Equipment

For the best solvent handling and usage procedure, it is recommended you utilized a two stage washing process: a dirty bath and a clean bath. The dirty bath is for removing the bulk of the excess resin and as such, it can be saturated with resin much more before having to be replaced. The second stage is the clean bath which has lower saturation limits and is responsible for deeper cleaning of the part. Eventually you will have to discard the dirty bath solvent but you can reuse the clean bath solvent as the dirty bath. Below are different washing solution options you can use. Feel free to use the combination of two that best suits your purposes (ex: wash basin for dirty bath, xWASH for clean bath).

xWASH

xWASH is a programmable, large volume washing station from Nexa3D built with ease of use and NXE400/NXD200 printer compatibility in mind. The station agitates the solvent to better wash printed parts and will pull the build automatically when the programmed time has elapsed. It includes a basket for washing individual parts and is also capable of holding the build plate itself with the parts attached (best option for minimizing distortion during curing process). This is the best solution for a validated workflow. 

Ultrasonic Cleaner

While not necessary in most cases, having an ultrasonic cleaner on hand can be useful for certain builds. Ultrasonics do a good job of cleaning out small blind holes or microfluidic passages. We recommend filling the ultrasonic cleaner tub with water and placing a secondary container inside with the solvent and the printed parts. 

Wash Basins

If resource or space constrained, using wash basins is a low-cost alternative to the above. The printers come with a small basin capable of holding a plate and small prints, but we recommend getting a large basin for use with medium to large parts. We have found the Ronco PE 10gal tanks (shown in our video) 18”x12”x12” (P/N R181212) are a suitable size for most cases. Keep in mind that a manual process like this has risks such as improper cleaning and accidentally over-washing the parts.

Solvents & Washing Guidelines

Nexa3D’s xCLEAN and Isopropyl Alcohol (IPA) are the recommended solvents for cleaning parts. You will want to wear appropriate personal protective equipment when handling solvents. Consult the SDS of the washing solvent you are using.

A hydrometer can be used to evaluate resin % content in the solvent (specific gravity change). Verify it has appropriate range and resolution for the solvent chosen. We recommend a hydrometer in the range 0.9-0.95 or 0.9 to 1.0, such as:

• Thermco GW107H (220mm 0.90-0.95)
• Thermco GW2538 (150mm 0.9-1.0)
• Thermco GW2558X (150mm 0.88-0.95),
• Cole-Palmer EW-08298-15 (165mm 0.89-1.00).

Avoid polycarbonate hydrometers which are not compatible with photopolymer resin or solvents.

For disposal, verify compliance to your local regulations. 

xCLEAN

Nexa3D's xCLEAN is an effective and eco-friendly washing solvent. It has three times the saturation limit as IPA (less changeovers and waste). It is much more effective at cleaning parts due to its small molecular size but it must be rinsed off afterwards. In most cases, you can rinse the part with water but you may want to avoid it for hydroscopic parts. See the rinse column on the table below for guidance based off resin. Keep in mind that xCLEAN is not cleared for use with biocompatible parts.

For xCLEAN, the maximum dirty bath saturation is 20% (.93 on hydrometer) and the maximum clean bath saturation is 3% (.91).

Pro Tip: Ice has a specific gravity of 0.92, so drop a solid cube in xCLEAN, it will sink when fresh and float when the xCLEAN is at or near saturation limit. Avoid cubes with air bubbles.

Refer to THIS page for specific wash and cure times.

Isopropyl Alcohol (IPA)

Isopropyl Alcohol is sometimes more accessible depending on your area but will wash at a much slower rate than xCLEAN and saturate much faster. However, it is often the only choice for biocompatible applications.

For IPA, the maximum clean bath saturation is 8% (.81) and the maximum clean bath saturation is 2% (.79). 

Videos

General Usage with xCLEAN

Safety with xCLEAN

Checking Quality of xCLEAN

• Nexa3D_wash_cure_summary (1).pdf100 KB

Updated August 19, 2024 22:32