Uncured Resin on Underside of print and creases on front


#1

Since I have gotten my Form3 I have been printing alot of hiRes prints so that I can cast them for some shows I am doing and sales on StoreEnvy. I am getting ready to cast but am worried that the uncured resin is going to inhibit the curing of the mold making or leave residue for casting.

I can scrape off the uncured resin on the back on the fronts where I am going to cast or there is detail I can only scrape so much. I do use a Form CURE and WASH. Is this the Resin not curing in the build? Problems in the wash not washing off resin? Any ideas before I start casting on these and have the probability of wasting a very expensive product in molding material.

thanks
jake


#2

Based on the geometry of the part and location of the support structures, I suspect that the uncured resin is not being washed off. I would recommend removing the support structures and then putting the part back in the Form Wash for another 5-10 minutes.


#3

Ok, see I tried pulling off supports and putting it back in upside down in the CURE tank and that didnt help. I figure that uncured resin needs to be removed or cured more but the CURE didnt do much to it. Maybe it needed longer. I will try the wash tank again too. Can you CURE or WASH too much though? Using Isopropyl Alchol 99.8% in my wash.


#4

One of the issues I see when doing a second wash after support removal is that the part is still soft.

The result is that it gets bashed about against the metal either other parts or the cage and that leaves witness marks. Is there a way around this, other than manual washing using the old wash system ?


#5

The liquid resin needs to be fully washed off before the part is put in the Cure. Once it has been cured, even with a bit of liquid resin still left, all bets are off.

Yes, it’s possible to wash for too long, but that would be much longer than the extra 5-10 minutes I recommend


#6

Alternatively use ultrasonic cleaner and detergent

Also use a brush to clean thoroughly the smallest details - in case of your complex shape the brush will definitely help…


#7

I am so sorry for the stupid question I am about to ask BUT consider me pretty new to alot of this. I am still learning alot here…

This is UNCURED RESIN that is still on the part. Does the FORM CURE I own NOT cure this resin fully? Is there something that the bath does to this RESIN that makes it NOT continue to CURE? Does that make sense? I thought the UV lights and HEAT in the FORM CURE would complete any curing that needed to be done? I own both the FORM WASH and CURE from Formlabs.

Luben111 thanks. Yeah, washed and used and old toothbrush to brush these sticky areas thinking maybe it would come off after the CURE and WASH stations. Nope, still sticky…it scrapes off but that isnt an option on the highly detailed areas on the fronts of these.

I may be pretty confused on all this now…haha! Sorry, Just seems cut and dry…1)3D PRINT 2)WASH 3)CURE 4)REMOVE SUPPORTS 5)MOLD 6)CAST…too easy right? ha!


#8

Not a stupid question.

The Form Cure is excellent at post-curing parts out of the printer once they have been washed to get optimal mechanical properties. Due to the chemistry behind photopolymers the UV light only penetrates so deep, so globs of uncured resin may not cure through beyond a certain thickness.

Your order of operations is good, although I prefer to remove supports before Cure. Just make sure that the parts are fully washed before you cure.


#9

looks to me like you are getting them pretty clean.
You just missed a couple spots.

The stickiness is due to oxygen getting at the uncured resin during cure.
You can try curing under water. We also get very good results with this stuff WickedEngineering makes called CURE GEL- its a clear gel you smear all over the surface before curing- definitely helps if you take supports off first- tho I don’t know how compatible that is with the cure station as we need to clean our curebox after we use it.


#10

I was reading about this (can’t remember where), I assume for you’d want to pre-heat the water to ± a couple of degrees of your curing temperature (if you’re using a heated curing chamber, or the Form Cure).

Whether the turntable motor is up to spinning with the weight of the water on top of it perhaps someone from Formlabs can chime in on.

Whatever I was reading on the topic also noted that cure time was reduced considerably using the water method.


#11

Something that I have done for a long time that I have never seen on the forum is use pressurized air. Not from a can like to clean a keyboard but from an air compressor. MAKE SURE THE NOZZLE YOU USE HAS VARIABLE AIR PRESSURE. You can very quickly, and easily, completely destroy a print doing this.

But the idea behind it is moving these globs of resin left over out of crevices and spreading the excess material over a larger area, thinning it out. If you know that your part is going to have excess resin in specific areas use the air to push it out of those areas directly out of the printer, before using the form wash. Then put the part into the form wash for ~5 minutes, as soon as it is complete pull it out of the form wash use the air to immediately dry it. You will immediately see areas that still have resin on them because they will look wet like your original photos. Make sure to use the air and spread the material out again and then wash again for ~5 minutes. If after doing this 2-4 times the area is still covered in excess resin then you need to use the alcohol bottle provided with the washing kit and directly spray the area with alcohol to remove it. Then using the air again immediately dry it.

Just as mentioned before with the UV light only being able to penetrate so far the alcohol can only dissolve so far into the excess resin to remove it. By spreading the excess thin over the larger area the washing will be much more effective in short bursts. It is more labor intensive yes, but you do not have to wait nearly as long to cure and the excess alcohol that has to evaporate off of the parts will never damage your surface finish if you dry it immediately with this method.

One final word of warning, make sure that you have something on the other side of where you are blowing the excess resin/alcohol slurry mixture. This can be rather messy, but if done properly can yield better surface finishes and truly clean parts.


#12

I don’t have the Form Wash- just the ordinary two pail cleaning system that came with the Form 2-

I soak in the rough tank- the use a brush to scour the surface details before soaking in the cleaner tank.
I then brush it again over the cleaner tank ( wetting the brush with ISP from the tank- then I use the squeeze bottle to hose down the surface with pure ISP.

THEN i take it outside and use the airgun from the compressor to blast off the remaining wetness.
I let it air pout of a couple hours so the ISP absorbed by the resin can evaporate out-

And then I do one of two things-
I smear CureGel all over it and put it in the curebox- ( curegel ain’t cheap )

Or I heat a clear glass bowl of water in the microwave untill its closer to the curing temp for the resin, stick the part in the bowl and place it in the Curebox.