The reason I chose LED strips was so I could wrap it around the outside of the jar so I could fill the jar with water. I suppose a clear glass dish filled with water inside a cabinet lit by bulbs would work too. Though maybe not as safely. But most of the resins don’t really need to be submerged. I set this up originally because I was printing Flex which needs submersion. But in truth I haven’t done it a lot and mostly I use the jar “dry”.
UV does not penetrate water too well. Your cure time may be really long if there is a good amount of water between your lamps and the part you are trying to cure.
Actually, it does. In the 400nm region the absorption of water is at a minima. In fact, UV (the frequencies we care about) penetrates water better than any other frequency of light. As you can see from this chart, Water hardly attenuates UV at all.
Also worth re-emphasizing that FL states that immersion in water is required for post-curing some resins. If the water absorbed UV, immersion in water would prevent the curing from occurring and FL would be wrong about the products they’ve designed. Which seems unlikely to me.
the info I know on UV absorption is that for our minimal distances (few cm) that the absorption in water is very minimal.
The water reduces oxygen on the surface. Oxygen on the surface impedes curing. Another tip is to use warm water (just from a warm faucet) which is meant to improve the material strength, according to Formlabs’ white paper.
Another important factor is that the parts must be clean! In an environment where people don’t keep their cleaning solutions clean and the Ultrasonic bath clean, this means the parts will be “sticky” no matter how much you post-cure. Use a fine artists brush to brush the surfaces during cleaning if you want to help with the cleaning. I also have magnetic stirrers in the Formlabs’ IPA containers so that the IPA solution (I use 50%) is constantly agitated.