Replacing The Polarized Film On Your Resin 3D Printer

So you’ve got a fancy LCD based resin printer. They’re great. They’re relatively cheap, and the results are stunning. However, after you use it a bit you’re sure to get familiar with the downsides, such as the wear and tear on the FEP film (the clear plastic film that separates the resin from the LCD screen).

If that FEP film gets a hole in it, resin can leak onto your screen. This alone is a bummer, but if you’re not paying attention and you let the machine try to print, you can end up with resin fused to the screen itself, a huge bummer. In some cases, this may mean that you need a total replacement of the screen. However, in many cases it may not!

Many of the MSLA printers use an LCD screen with a polarized film on it. All of them I am familiar with do, but who knows, there may be some without. Though the manufacturer may not necessarily recommend it, you can actually replace that polarized film!

When this happened to me, I was very frustrated. It was a brand new printer, having only had one successful and very good looking print out of it. As I scraped the cured resin off the screen, I damaged it, and was super bummed. I thought I’d need to replace the printer, or at a minumum, replace the screen. After some research I found that some groups had shared positive results in replacing the polarized sheet on their printer. There wasn’t a ton of information out there though, so I had to do some major trial and error.

Here are the steps to replacing your polarized film. Keep in mind, your specific printer might not have a removable film.

1. Remove the old one
   Carefully scrape and peel your old one off. This is tricky and scary. You’ll need a clean razor blade and some patience. Keep some scraps to compare to the new film you get.
2. Clean clean clean
   There will be bits of glue residue left behind. I used alcohol to remove it. Acetone might work as well (but acetone can melt many plastics, so test in a corner). You’re going to need this LCD screen perfectly clean.
3. Acquire the proper replacement
   This is the tough part. There’s often zero documentation on what film will work! Even the printer manufacturer has no idea as the film comes pre-applied on the displays! I used this one (Affiliate Amazon Link). It worked quite well.
   
   I experimented with this one first (Amazon Affiliate Link) and it did not block enough light. I didn’t notice that it says “not for 3D printers” in the description.
4. Find the correct angle
   Lay the sheet on the printer, fire up the UV light source, and slowly rotate the sheet to see where it blocks the most light. Look at the video above for this in action. You CANNOT simply cut a rectangle and plop it on. You need to have it at the correct angle.
5. Cut to size
   This is as simple as it sounds. just cut it.
6. Mount
   For adhesive backed polarized sheet, you’re going to need to carefully apply it so that it has no bubbles. There’s often a protective layer on both sides. I’d keep the top layer in place till it is fully applied to avoid marring the surface. Look up videos on applying vinyl decals on how to apply this stuff without bubbles. I’ve been doing that for years, and I still messed it up a couple times.
   
   Alternatively, if your film does not have an adhesive backing, you can literally just tape the edges down. As long as it stays firmly in place, is clean, and there’s no gap between it and the LCD, you’re set!
7. Print
   You may now use your printer again.