Resin question

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philipy
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Resin question

Post by philipy » Sat Mar 06, 2021 6:51 pm

I think I have problem and I think I know the answer, but I'm interested any comments/ideas anyone may have?

I used my resin printer yesterday and today, for the first time for a couple of months, and I keep having the same problem which I hadn't seen before.
As I poured the resin into the vat I had a passing thought that it looked a bit thick, but didn't pay it much attention. However, I've tried to re-print something which printed perfectly before and keep getting two problems:

a) The fine detail is rounded/blurred where it was really crisp originally.
b) I'm printing number plates on supports and I keep finding that the raft and supports print perfectly and the plate itself starts to print but by the time it finishes the part printed number plate is laying in the bottom of the vat and the raft and supports are stuck to the build plate where they should be.

I think the reason for both is the viscosity of the resin, in that it doesn't run off each layer properly and so the next UV shot fuses some more resin onto the edges of the previous layer. This in turn of course slightly increases the weight and then the viscosity plus weight causes the whole thing to break free of the support attachment points.

So I come back to resin storage. I have made sure to filter the unused resin as I pour it back into the original opaque bottle which is in turn stored out of direct light. However, it looks to me as though it is slowly curing in storage. Does anyone have any thoughts on this?
Is pouring the resin back into the bottle contaminating the unused resin and causing the whole lot to degrade?
Would it be better to actually throw away the unused resin in the vat, or at least keep it in a separate bottle?
If so will it protect the 'new' resin in the original bottle or will that degrade anyway once opened?

Thoughts?
Philip

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Re: Resin question

Post by -steves- » Sat Mar 06, 2021 10:54 pm

Only one thought and I am sure you do, but do you shake vigorously before using your resin?
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Re: Resin question

Post by philipy » Sun Mar 07, 2021 6:25 am

Yes, I do give it a good shake.
Anyway, I would assume that if there is any tendancy for it to settle, the thicker stuff would be at the bottom so I'd expect it to be initially thinner when pouring?
Philip

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Re: Resin question

Post by -steves- » Sun Mar 07, 2021 7:32 am

philipy wrote: Sun Mar 07, 2021 6:25 am Yes, I do give it a good shake.
Anyway, I would assume that if there is any tendancy for it to settle, the thicker stuff would be at the bottom so I'd expect it to be initially thinner when pouring?
Twas just my initial thought. How long have you had the resin open?
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Re: Resin question

Post by philipy » Sun Mar 07, 2021 7:51 am

Almost exactly 3 months to the day since I first opened it. It has subsequently been used about half a dozen times, but of course that also means half a dozen lots of 'used' resin being returned to the bottle. In my own mind I strongly suspect that that is the problem.
I'm guessing from your responses that it isn't a problem you've encountered?
Philip

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Re: Resin question

Post by -steves- » Sun Mar 07, 2021 8:17 am

philipy wrote: Sun Mar 07, 2021 7:51 am Almost exactly 3 months to the day since I first opened it. It has subsequently been used about half a dozen times, but of course that also means half a dozen lots of 'used' resin being returned to the bottle. In my own mind I strongly suspect that that is the problem.
I'm guessing from your responses that it isn't a problem you've encountered?

Sort of. I did tend to find the more I tip back in the thicker it got but had no noticeable affect on the print, but now I tend to leave resin in the tray for up to 2 weeks as I try to refrain from putting it back in the bottle as much as possible and print as much as I can in one go. I save my resin prints up until a larger run these days. I have a print sitting on the printer that's been there over a week now, I really should get that cleaned up and something else printing, lol ;)

Just trying to rule out things one by one, same as yourself, it's all a learning curve.
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Re: Resin question

Post by philipy » Sun Mar 07, 2021 8:59 am

Makes sense to stack up the prints and do them in batches, but then you do a lot more printing than me, with your loco prints etc.

I think I'm going to reserve what I've got left in this bottle for doing larger/more robust prints with somewhat less critical fine detail than number plates. Then, going forward I think I'll try to keep returned resin separate to its parent bottle.

I've never been keen on the idea of leaving resin in the vat, although I know people do that and Thingi has a load of vat covers and storage racks for multiple vats. I did leave it overnight once and found that a gelatinous rim had started to cure round the walls of the vat by the next day, and since then I always pour it back as soon as I've finished a print session.
Philip

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