Waterproofing 3D prints

I'm currently doing some development on 3D printed piezo inkjets (I'll post in the appropriate place when I have something to show), although am having a problem with water seeping into my parts. Could anyone recommend any techniques I could use to waterproof my parts? Here are a few options I'm currently aware of:

• Increase flow rate to reduce the chance of small gaps in the print.
• Cover the print in a laquer or some other coating to seal it. What is the cheapest option? Will something like a coating of PVA glue work?
• Print in ABS instead of PLA. Unfortunately I am not capable of printing ABS currently.

Many thanks,
Sam

This is why printed parts (FFD anyhow) are not really considered food safe, despite using food safe materials, there are always micro cracks where moisture can get trapped. A coating is the only way you will ensure that it's 100% water tight.

All of my ABS prints are water tight. I hear people mentioning this all the time and I feel it might be due to slight calibration issues. On my machine I can print a .2mm single layer and it's fully water tight (does not look like lattice work with little holes in between). This is because mine will extrude enough material to make it touch the last stripe next to it, this makes for a water tight print especially after a few layers.

If you print in ABS you could also use vapor bath to smooth the surface and this also fills in micro holes but it's best to jack up the extrusion width a bit to make it right from the start, then if you want you can vapor smooth it to make it smooth.

So, look close at your prints, can you see any gap between the passes where the plastic is laid down? If so then that's why the prints are not water tight. Think of it like mowing a lawn, if you mowed with gaps between rows then you would have little streaks of tall grass between rows right? well if you do this with 3d printing you end up with slight gaps instead. The cure in our case is to use a slightly wider mower because you can't change where the mower goes, more plastic extrusion will spread out and thus connect the rows forming a water tight bond between them.

I hope I made that clear and hope it helps.

Edited 1 time(s). Last edit at 04/20/2014 06:24AM by tmorris9.