Post curing in water, or dry

#1

What are the pros and cons of post curing in water? Is it worth it or is curing dry just as good?

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#2

Strictly speaking, water doesn’t cure the resin. Only exposure to UV does that. Water can help rinse solvent/resin residue off, but I don’t think would be much benefit of soaking the parts while exposing them to UV - it would probably just hinder the process.

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#3

Curing in a water bath can help increase surface hardness. It works because water contains considerably less free-roaming oxygen than air does. Air contains about 20% oxygen, but water contains less than 1% dissolved oxygen. Oxygen can inhibit radical polymerization of UV curing resins, leaving parts feeling tacky to the touch.

Water does absorb UV light, the absorption is not significant at the wavelengths used to cure UV resin. So you don’t have to add much exposure time if you cure your parts in a shallow tank of water.

There are really no “cons” to curing in a water bath, other than getting your parts wet and require drying. You should give it a try and see if it improves the surface hardness of the parts you’re printing.

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#4

I always cure under water because it speeds up the curing time and gives great results.

Here you see the printed objects in a jar of tap water in the middle of the curing chamber.

https://forum.peopoly.net/uploads/default/original/2X/0/0a08d17287180cbc9e5d1125da19549565dca093.jpg

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#5

I did not know that! I’ll have to give that a try. :slight_smile:

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#6

water helps a lot and it is our recommended way to post cure. it speed up the process by couple times over and the print has a clean finish.

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#7

I once tried curing underwater and while it helped curing a lot, it introduced “bubbles” on the surface finish which I guess they were there already (air bubbles in the water).

Is distilled water any better or no dfference at all?

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#8

Curing under water do generate bubbles on the surface of the objects but I have not noticed any negative effect on the surface finish.

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#9

we have not notice any difference. We usually just throw it in a Ziploc bag and blast away with UV light. works well with minimal water usage.

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#10

Very very very little difference, as the distilled water has less suspended solids in it, but not worth using.

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#11

I actually just had this happen, extremely badly. Chicago water is notoriously cloudy from the tap (warm water) then becomes clear, but I apparently didn’t let it sit enough. I cured for 10min as I usually do in water and HOLY COW my pieces are covered in bubbles. It’s like I made them out of sandpaper. I need to let the water sit for a while it seems.

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#12

Try adding an aerator to your tap. It should help clear up the cloudy water much faster.

I always get my highest quality parts by thoroughly washing in an IPA bath with dish soap and a toothbrush, then rinsing the IPA off with soap and water, and then dropping the part into a vat of fresh tap water for curing. I always dump the rinse water and curing water after each batch of parts to avoid any floating resin particles from adhering to the next batch.

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#13

Try something like this. You fill the vase with water, and it dramatically lowers curing times.

DIY Curing Vat

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#14

The is a stl designed for our UV led. You can fill water in the lower chamber.

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#15

Unfortunately, the STL for the curing box to be used with the peopoly light is only printable on the moai 200 unless you split each side into multiple pieces and reconnect them. It seemed like a huge hassle just to make a box. Also, I was concerned the size of that 3d printed box might be too small. I’m often printing parts that approach the limits of my moai 130’s print area.

I used a 5 gallon “paint bucket”. I primed and painted the interior with reflective silver paint and sealed it with laquer. I got two of the peopoly UV lights, spliced them together so there’s only one power cord/switch. I cut holes in the bucket lid, and affixed the lights with some regular bathroom caulk I had in my garage. It works great, it’s portable, sturdy, and cheap. Buckets are $5 at stores like “home depot” or “lowes” or “ABC Hardware” or “scotty’s”. Spray paint is about $4 a can, and I used 3 cans (primer, paint, laquer coating). $35 for the second UV light (first one came with my printer). Altogether about $55.

It doesn’t look as nice as the 3d printed box, but it’s bigger, waterproof, easy to replace, portable, sturdy.

Electrical: The combination of the two peopoly UV lights draw 0.176a of current on US 110v (actually 121.6v). That’s 21.406 watts. So each light draws approximately 11w. This could easily be converted to a portable unit with a small voltage multiplier and some 18650 rechargeable batteries. Four 3ah 18650’s should run it for nearly 70 hours (not accounting for losses in the circuit).

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#16

What I did was to get a glass vase and I painted the outside with Mirror Effect paint, so now the light ( bounces ) off the sides and gets every where for a full cure under water.
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#17

That’s a great idea! I might try using a fish bowl and mirror paint. I think that would turn out better than my bucket.

fishbowl

I could glue the UV lights to either side. I’d like to find a “cookie jar” type lid for it.

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#18

Paint the whole bowl then put clear plastic or glass over the top and put your lights there.

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#19

Any kind of closable, opaque container will work. Doesn’t have to be fancy. I’ve been using a tupperware bowl lined with aluminum tape. Works fine.

20190421_115332

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