Sciencemadness Discussion Board

When drying salts how do you prevent cake formation sticking to glass?

alking - 10-1-2017 at 17:33

If the salt is non reactive with Aluminum I could put some foil under it, but otherwise I don't see a way around this, and aluminum is often reactive. For instance I wouldn't trust it with some copper chloride. So once it's stuck I either lose some product or worse some glasswear. Are there any tricks I'm not aware of?

TheMrbunGee - 10-1-2017 at 21:30

How about using plastic containers to dry them?

Chlorine - 11-1-2017 at 04:45

You can dry them on a coffee filter with some paper towel underneath, however, you will loose a small percentage of your product. You could also use a plastic watch glass, you'll recover all of your product but you'll scratch the plastic up pretty bad.

WGTR - 11-1-2017 at 05:44

Solid PTFE sheet? Not very many things will stick to Teflon. It looks like ePlastics sells something like this.

http://www.eplastics.com/Plastic?search=Ptfe

Otherwise, maybe some non-stick cookware.

MrHomeScientist - 11-1-2017 at 06:40

ePlastics is a great company. Their sales reps work closely with you to make sure you get exactly what you need. I've worked with them several times in the past for my periodic table display projects. You buy one large sheet of plastic and pay for the number of cuts you need to produce the parts you want. You pay for a range of cuts (i.e. 10 - 20 cuts = $X.xx), so they actually cut the rest of the sheet for me and I got a bunch of extra pieces for free.

Slightly off topic but I wanted to put in a good word for them :cool:

Eddygp - 11-1-2017 at 07:08

There are a few impermeability/anti-stick spray on products around. You could potentially use that on a plastic watchglass (watchplastic :P ) and see whether it goes better.

DJF90 - 11-1-2017 at 07:24

I don't see what the problem is? Just scrape it with a spatula.

alking - 11-1-2017 at 07:47

A teflon sheets sounds great. Wouldn't plastics melt though? What kind of plastics did you have in mind? CuSO4 which is what made me question this dehydrates at ~205C or so iirc, so the plastic must stand to at least 250-300C.

Just scraping with a spatula doesn't always work. Often I will have products fused to the sheet tightly. If it's something like MgSO4 or something really cheap I don't mind losing 10% by washing it out, but for instance this time I have about half of my CuSO4 stuck to the glass. So not only did I only get a 50% 'yield' but the CuSO4 is not super cheap (not that it's expensive) and it's not something I'd want to wash out and dump down the drain in appreciable quantity due to the toxicity as well.

Herr Haber - 11-1-2017 at 11:14

Teflon is great. Unless you'll be putting in something that is sensitive to static in which case I would not recommend it.
(Thanks for the supplier by the way)

But for what you seem to be doing, maybe some aluminium trays could be used ? The thin ones you get your food in at lunchtime, not the heavy duty ones actually used for cooking.
I got some for that very purpose from a cooking / kitchen store. They exist in all sizes, are cheap and will withstand the heat in the oven.
After you are done you can discard it and still have 99 left in the pack.

That's about the only thing I can think of that's cheap, withstands high temperature and that you can bend and scrape to your hearts content to collect as much as you can.

PHILOU Zrealone - 11-1-2017 at 14:29

Fluidized bed drying should avoid the sticking of salts.

JJay - 11-1-2017 at 14:50

I've done this with copper (ii) chloride by just stirring occasionally. The problem I ran into was with severe bumping of the solution as the hydrated crystals formed, which threw corrosive copper (ii) chloride solution all over the inside of the oven. Definitely don't use an important oven for this.

alking - 11-1-2017 at 18:02

Quote: Originally posted by PHILOU Zrealone  
Fluidized bed drying should avoid the sticking of salts.


What is this?

j_sum1 - 11-1-2017 at 18:10

Think air hockey table. :)

DrP - 12-1-2017 at 04:30

Why not just a standard filter paper and Buchner? I never liked using the fritted glass filters, especially for fine stuff. a)I could never get all my product off of the glass. b)I was never confident it was 100% clean.

So - collect on a filter paper and dry it on the paper on a petri dish in a vacuum oven. ftw.