Coating petri dishes

[cadsmith]

is there a guideline for coating the petri dishes?
are the petri dishes still the way to go or is there a better vat ?
I purchased the nalgene dishes and the coating as suggested but don't know how thick etc to make it.

Thanks

Thomas

[maurice]

I would be interested in guidelines on both: How to coat the dishes and when to coat them. The dish I used the most is starting to get a milky PDMS coating, so I assume, the light will no pass trough anymore in a satisfying amount to cure the resin.

I found a guidline for the B9 creator (which also uses a projector) on how to coat the vat, but it's in german: https://starship-factory.ch/2014/01/05/ ... b9creator/

[Scatterplot]

Alternatively you could probably put it in a vacuum chamber if you have one available. We use one at work on various epoxies and it works really well to get rid of the bubbles introduced during mixing.

[goopyplastic]

This is a pretty good video and the info applies to us as well:

https://www.youtube.com/watch?v=q3Aw_ZG4V4E

You want to make sure the dishes are on a level surface, use a bubble level to make sure.
Mix 10ml of the larger part to 1ml of the smaller part (multiple for more dishes).
Mix thoroughly until milky with bubbles, bubbles are fine they will come out on there own (it is suprising).
Place 10ml of mixture in a dish, cover to prevent contaminants and let cure for 24 hours.

[maurice]

I managed to destroy some coatings before it got cloudy, that would be an indicator too...

[deadmeat30]

too long exposure time no doubt.

[maurice]

I am afraid it's not that simple: The first one was the victim of Windows forcing an update an showing the desktop background on the projector over night, that was overcuring for sure.

The there is an issue since I did get my new MakerJuice resin, but I want to open a seperate thread for that topic.

[maurice]

I started recoating petridishes today with Wacker Elastosil RT 601, and my new leveling table, that I will of course share with you, when I am in my workshop again (in case anybody is interested )

I am trying to source petri dishes in Europe, but I cannot find the Nalgene 5500. Probably it's sold under a different Brand name?
Does anybody know where to source Nalgene 5500 or comparable petri dishes (in Europe)?
Or what would be the specifications for the dish, so I can search a replacement on my own?

[maurice]

In the Q&A of the Amex site its stated that the dishes come empty.

PS is not suited, as it is not durable enough (http://www.hirsch-gruppe.com/homepage/a ... tyrene.pdf)

The Duran dishes look interesting, but they are not cheaper, if you order 60 Nalgene dishes at one time.
The only issue that can occur is the light of the projector not being able to penetrate the glass of the dish well enough, so I think I will give the Duran a try once.

[goopyplastic]

The nalgenes are sold uncoated, you won't be able to find a pre-coated petri.

In a pinch you can use 100mm styrene petris, just keep an eye on them as the plastic will react / fog etc.. so they are more disposable than anything else. Also with thin petris, they will bow downwards with the force of the build plate when homing, so you can back them off a little to remove the bowing.