Maintain and clean each resin tank using Formlabs instructions to maximize tank performance and to ensure consistent, high-quality prints over a tank’s lifetime. Only use approved materials and processes to clean the resin tank and film.

A failed print may leave small, partially-cured pieces of resin floating in the tank or hard cured resin stuck to the film in the base of the tank. Remove debris from the tank film by hand or by printing a cleaning sheet. The cleaning sheet prints as a thin layer across the resin tank, binding cured and partially cured resin into a single piece. The cleaning sheet can then be removed from the tank along with the failed print.

Printing a cleaning sheet

The cleaning sheet is a thin part that prints directly on the resin tank film and is perfect for removing print failures or hard to find debris from the resin tank. It should take approximately 2–15 seconds to print, depending on the material. All Formlabs resins have predefined cleaning sheet print durations.

With firmware 1.15.0 and later, you can also set a custom cleaning sheet printing time on a per-resin basis. This can be useful if you are printing with custom print settings or a third-party material via the Print Settings Editor and Open Material Mode. It can also help if you have had issues with the Formlabs default print times in the past and want to optimize your workflow.

For best results, Formlabs recommends using a cleaning sheet holder when printing a cleaning sheet.

To print the cleaning sheet holder:

1. Update PreForm to the latest version.
2. Download the appropriate FORM file for your printer from the links below.
   1. Form 4 cleaning sheet holders (66 cleaning sheet holders)
   2. Form 4L cleaning sheet holders (162 cleaning sheet holders)
3. Open PreForm.
4. Upload the file from your computer and start the print. Formlabs designed this part to be printed on a Formlabs SLA printer with any material. The cleaning sheet holder does not need to be printed in the same resin type.
5. Wash and post-cure the cleaning sheet holders.

To begin printing the cleaning sheet:

1. Check that no job is currently active and your printer is in the Idle status.
2. Insert the tank that experienced the print failure into the printer.
3. Press down on the sides of the resin tank with your thumbs and close the latches to secure the tank.
4. Remove the mixer, build platform, and resin cartridge, if present.
5. Tap Maintenance > Print cleaning sheet. The Print cleaning sheet screen appears.
6. Place the cleaning sheet holder at the center right edge of the Light Processing Unit (LPU) with the flat side of the holder gently touching the resin tank film. Alternatively, use a clean piece of support with a raft and place it at the corner of the LPU.

7. Optional: To enter a custom cleaning sheet printing time, tap Edit. Enter a print time in seconds, then tap the check mark to save and return to the previous screen.
• The maximum print time is the length of time required to reach an exposure of 5000 mJ/cm², the same maximum exposure you can set in the Print Settings Editor.
• When printing with a custom print setting, the default print time is the same as for the Formlabs material on which you based the print setting.
8. Tap Start. The cleaning sheet begins printing.

Removing a completed cleaning sheet

The cleaning sheet causes other bits of cured resin to adhere and become caught in a single part. After the cleaning sheet has finished printing, it’s time to remove all cured resin from the resin tank.

To remove the cleaning sheet from the tank:

1. Ensure that the print has completed.
2. Open the printer cover. Do not remove the resin tank.
3. Carefully lift the cleaning sheet holder and peel the cleaning sheet from the resin tank. Take care, as the cleaning sheet drips resin.
4. Hang the cleaning sheet holder on the build platform draw bar to reduce resin waste.
5. If the cleaning sheet remains adhered to the resin tank or a cleaning sheet holder was not used, place the edge of the included plastic tank scraper flat on the bottom of the tank next to one corner of the cleaning sheet. The cleaning sheet may be difficult to see for opaque resins. The cleaning sheet prints over the Light Processing Unit (LPU) below the resin tank, so the corners of the cleaning sheet align with the corners of the LPU.
6. Carefully lift the corner of the cleaning sheet with the plastic tank scraper.

7. Peel the cleaning sheet away from the tank film.

8. The cleaning sheet is cured resin and can be deposited in any trash receptacle. If there is uncured resin on your cleaning sheet, roll it up with gloved hands and squeeze out the resin before disposing of it. Alternatively, place the cleaning sheet on a sunny windowsill for 24–48 hours until all resin has completely cured.

Removing cured resin manually

Use the plastic scraper that comes with the Finish Kit or a similar tool to remove individual pieces of cured resin from the resin tank. Apply minimal force to remove the cured resin. Avoid using the corners of the tool to dig under the print.

1. Open the printer cover.
2. Use the flat edge of the plastic tank scraper to scrape cured resin off of the film.
• Scrape laterally using the flat side of the tool to get its edge under the cured resin.
• Continue scraping or twist the tool to lift the resin off of the film.

Keep the resin tank—especially the top and underside surfaces of the film—clean and free of cured resin and other debris to ensure print quality and extend the lifetime of the printer.

Cleaning the wear strips

Form 4 and Form 4L generation resin tanks contain two wear strips, which are mounted above the tank film and protect the film from the mixer. Inspect the wear strips regularly to ensure no debris is caught underneath the tank film.

To clean the resin tank wear strips:

1. Wearing gloves, remove the resin tank from the printer and place it on a clean work surface.
2. Remove the mixer from the resin tank and set it aside on a protected surface. Take care not to spill resin when removing the mixer.
3. Gently grasp the wear strip and remove it from the resin tank.
4. Apply a small amount of clean IPA to a disposable non-abrasive lint-free wipe and wipe the surface of the wear strip to remove contamination or resin. Allow the wear strip to air dry before reinstalling it.
5. Use the plastic tank tool to ensure there is no partially cured resin stuck to the tank film.
6. Align the wear strip with the mounting posts along the edge of the resin tank. Align the middle mount points and hook into the mount holes. The two outer mount points click into place. Ensure all mounting points are secured and mount both wear strips.

7. Insert the mixer into the resin tank. Ensure that it moves freely along the wear strips.

Cleaning the tank film

The bottom of the Form 4 and Form 4L resin tank is made of a transparent film. Light shines upward through this film to cure the liquid resin in the tank. Any scratches or debris on the tank film will cause defects on printed parts. Resin can cure inside large flaws in the film, creating deposits that can cause errors and print failures. When interacting with the Form 4 or Form 4L resin tank, take care to avoid scratching, denting, or puncturing the film.

To clean the tank film or film underside:

1. Empty the liquid resin from the resin tank into an opaque container.
2. To clean the tank film: Place the empty resin tank on a clean, flat surface.
   To clean the film underside: Place the empty resin tank upside-down on a clean, flat surface.
3. Apply a small amount of clean IPA to a lint-free cloth.
4. Wipe the surface of the film to remove contamination or resin. If visible residue or streaks remain on the tank film following cleaning, use a fresh cloth and additional IPA to wipe down the bottom of the tank until no streaks remain.

Cleaning the resin tank exterior

To clean the resin tank exterior:

1. Use a lint-free cloth and clean IPA to remove contaminants from the resin tank exterior.
2. Keep the sides of the tank clean and free of resin.
3. Ensure no debris or resin is present on the bottom of the resin tank, as this will come into contact with the LPU when the tank is returned to a printer.

Clean the plastic tank scraper after each use to remove excess liquid resin and prevent contamination.

To clean the tank scraper by hand:

1. Apply clean IPA to a clean paper towel.
2. Carefully wipe the surfaces of the tank scraper to remove resin.
3. Allow the tank scraper to air dry.

To clean the tank scraper using the Form Wash:

1. Place the tank scraper in the Form Wash basket.
2. Set the Form Wash wash cycle for 5 minutes. Increase the wash time for heavily-used solvent.
3. Allow the tank scraper to air dry after washing.

After removing the primary print failure, inspect the resin and tank for other small fragments. While the mixer keeps the print area clear during printing, clean resin and optical transparency in the bottom of the resin tank are always the best way to ensure quality prints.

If you see or feel any resin cured in your tank, it's essential to remove debris by cleaning the tank or the next print will fail. Use a paint filter with a "Fine" or 190 micron mesh size to thoroughly strain liquid resin.

Print failures often leave behind small pieces of cured resin that can easily lead to future print failures or surface defects on your parts. The Form 4L resin tank debris catchers help prevent this by filtering out these pieces of cured resin and sequestering them at the sides of the resin tank, away from the print area.

Clean out the debris catchers if you notice large, loose debris or when they are more than halfway full.

To clean the Form 4L resin tank debris catchers:

1. Put on a pair of clean nitrile gloves.
2. Set the resin tank on a table with the front facing you, in the same orientation you would insert it into the printer. The LevelSense spout should be in the back-left corner.
3. Locate the right debris catcher, installed under the lip on the right side of the resin tank. Pinch the removal tabs on the debris catcher. Pull the debris catcher tab up and towards the middle of the resin tank until it comes free. Be careful not to splash the liquid resin in the tank or spill any debris out of the debris catcher.
4. Empty the debris catcher and wash out any remaining debris with IPA.
5. Reinstall the debris catcher into the resin tank.
6. Repeat steps 3–5 for the left debris catcher.

Reinstall the debris catchers after cleaning out any debris. To install the Form 4L resin tank debris catchers:

1. Put on a pair of clean nitrile gloves.
2. Set the resin tank on a table with the front facing you, in the same orientation you would insert it into the printer. The LevelSense spout should be in the back-left corner.
3. Locate the right debris catcher, which has the letter R printed on its top face. With the letter R visible and upright, place the debris catcher into the resin tank.
4. Slide the right debris catcher towards the right side of the resin tank.
5. Press the debris catcher into the right side of the resin tank, pushing firmly at both ends. Each end of the debris catch should snap into the tank frame.
6. Lightly tug on the debris catcher to ensure it is secure. When the debris catcher is properly installed, it does not hang over the inside of the resin tank frame.

7. Repeat steps 3–6 for the left catcher, which has the letter L printed on its top face.