Hot water rinse between the 1st and 2nd IPA bath

I’ve been experimenting with finishing steps and found that rinsing parts under a tap in hot water between the 1st and 2nd IPA bath is a good way to get rid of tackiness without marking the surface as sometimes happens if you try to wipe parts down with a cloth after the IPA baths. It also makes your 2nd tank of IPA last much longer :wink:

After you’ve rinsed the part in hot water the surface is soft and greyed (so best to avoid touching it, I always hold it by the base while doing this) but after being in IPA again and cooling down it gives a nice shiny surface finish.

Here’s a Marvin printed at 25 micron layer height and finished with this technique , you can still see the individual polygons that make the model up.


I’m definitely going to try that, thanks for the tip :smiley:

Nice tip! thanks, will try. Is the water just hot and not boiling?

Yeah just straight from the hot water tap, not boiling. My hot water is particularly hot, but not hot enough to scald or anything.

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I tried this today. After the hot water runs the part almost seemed gooey, but the final IPA rinse made it perfect. Seems like a good tip.

It helps, thanks.

I put my parts in the first IPA bath and slosh the container with the lid on for about 30 seconds. Then I take the part and slosh it in a container of warm water for 10 seconds. Finally I let it soak in the final IPA bath for about 5 minutes. The water rinse step really gets a lot of the goop off of the print and makes the last IPA bath last a really long time. If you make the water too hot it can cause the part to warp and the hotter the water the more haze it creates on in the part.

Great tip… I must try it.

One question. How long you maintain IPA?. When its good time to change for new one.

I generally discard the first IPA when its too dark (practically black (i use black resin) May be 40 or 50 prints) , then replace by second IPA that its parcially clear (which becomes the first). Then use the new one as second IPA.

I usually change mine every 20 prints or so, Jose. Judging on the color is subjective as it doesn’t change as much if you don’t use a lot of black resin in that period. That’s why colour indication may not be the best way to do it…

I chaged it at two litters of resin… i only notice that some object sees a little more bright spots after being clean, but not affect parts nothing in finish, including paint, and it cures well.

I have a UV lamp that I use to cure parts and I also leave it turned on over the top of my IPA tank. That causes some of the resin to cure and fall to the bottom of the tank. I would guess that probably extends the life quite a bit. I’ve probably gone through a few liters of resin now and I haven’t changed my IPA yet. I have added a good bit to the first tank since the level gets lower over time. Its very dark right now but I’m not going to change it until it stops getting my prints clean. Rinsing with hot water after the first IPA rinse keeps the second tank very clean so I would imagine it will last for over 10 liters or more of prints.

Here’s the UV lamp that I use.

I also have a UV sterilizing cabinet but I rarely use it since it takes about 10x as long to cure parts as the UV lamp listed above.

Interesting, I will give it a try.

Tony, I notice that the UV lamp you are using is 380 nm. The Form 1+ and Form 2 are both 405 nm. I assume you get some post cure with your 380 nm lamp on the parts, but maybe not as much as with a 405 nm source. Have you used it with the flex resin, which would be a good test to see how effective it is?

I pour my first IPA in a separate gallon jug when it gets very dirty, let that settle out several days and then slowly pour off the clear-ish, used IPA back into the first bath.

We use a lot of black too and once you let the solids settle, the pour off IPA is sorta grey…but still works fine for the first bath.

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