# Filter paper?



## Joeforbes

What would be a recommended brand and micron size of filter paper for vacuum filtering?


I'm sorry if this has been covered in another thread. I tried using the search button but I really couldn't find the answer.  

Thank you.


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## Oz

That depends entirely on what you want to filter.


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## Joeforbes

Mixed Pt/Pd/Rh sponge, Au sponge, Pt and Pd salts mainly. The papers I use now filter fine, but the problem is getting what is filtered out off of the filter paper. I've tried rinsing it, letting it dry and scraping it off, scraping it off while wet. Bah! lol.

Lazersteve seems to be able to rinse the powders and sponge off fine, so I assume the problem is my type of filters.

Sorry, I should have been more specific.


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## eeTHr

Decant instead of filtering, whenever possible.


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## Joeforbes

I siphon as much as possible. 

I just need to know a good brand of filter paper please...


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## samuel-a

i'm not sure if this is the brand, i think it called 'duble ring'. China made.
Rated medium speed '102' qualitive.
So far so good.


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## goldsilverpro

I think Harold used Whatman #2 for general purpose work and Whatman #5 for finer material. Don't buy Whatman #42 unless you want to wait all day for it to filter. I spent most of my life using S&S 596, which they stopped making a few years ago. Whatman bought out S&S and maybe they have an equivalent. Most of these papers are expensive, especially in the large diameter sizes (some can cost $1 per circle, or more). Whatman (or, S&S) Sharkskin is a very thin paper that is quite cheap and works very well for some gross separations. All these can be purchased through a lab supply company.

Here's a supplier of the Double Rings paper that Sam spoke of. If I were to buy any of this, I would probably try the 102 (qualitative - medium speed) paper first.
http://shop.ebay.com/avogadroslabsupply/m.html?_nkw=filter+paper&_sacat=0&_odkw=&_osacat=0&_trksid=p3911.c0.m270.l1313

This might be the same stuff but it seems a little cheaper. They don't say, though, whether it's fast, medium, or slow.
http://shop.ebay.com/onlinesciencemall/m.html?_nkw=filter+paper&_sacat=0&_odkw=&_osacat=0&_trksid=p3911.c0.m270.l1313


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## Harold_V

If memory serves, Whatman 42 is intended for vacuum filtration. Assuming that's correct, it would be a miserable choice for gravity filtration. 

Chris is correct---I used Whatman #2 for filtering my solutions that were headed for precipitation. It is fast and retentive, although there were occasions where I'd have to re-filter the solution until it was clear. That's the price you pay for having a fast filter. Otherwise, they are subject to premature blockage. Whatman #5, for instance, would be a poor choice for filtering first run materials. I used that grade exclusively for filtering my re-refined gold. Because the solution was virtually free of contaminants, filtration was reasonably fast. 

I, too, liked the old Sharkskin filters, and used them exclusively for filtering polishing wastes. I wasn't concerned with traces of contamination following the solution---it got removed in the final filtration. Sharkskin was one of the handiest of all filter papers---just a little too open for fine filtration. Again, that's the price you pay for speed. 

Harold

edit: a search reveals that Whatman #42 is satisfactory for gravity filtration, but is very retentive, thus slow.


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## Sucho

i use Munktell Filtrak papers 388 ,389, 390. its like Whatman grade 41, 43, 44

388 is great for large particles and gels.your filtration is faster due to large pores.i use it for gravity filtration
389 is almost universal
390 is great for very fine separation, but only with a "clean" sols and only vacuum filtration


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## elfixx

I would not suggest Double ring 102 if you plan on using them in a buchner with vaccum, they have a tedency to rip appart during filtration.


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## Joeforbes

I do use a vacuum filter with a buchner funnel.

Thank you for the replies.


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## Joeforbes

Update -

After testing several brands and pore sizes of filter papers, I've decided on using United brand #1 filters. 

They work well in most situations, are durable, and are relatively inexpensive. Sometimes a very mucky solution will slow them down, but otherwise they filter decently fast.

I just figured I'd update this with my experiences in case anyone else reads this thread looking for a good brand of filter papers.


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## Claudie

Thank you Joe.


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## Clneal2003

I'm saving this thread. I'm tired of coffee filters. All my equipment is getting up there in quality but I'm still using coffee filters. I just checked the price on Whatmans and they are rediculously expensive for some of them. I'll keep searching and report back on results. My next big purchase is a small Büchner funnel and flask. I've got a hand vaccuum pump I'll use for a while in conjugation with the buchner. 

Keep posting reviews though. I'd hate to spend $70 in filters and end up not really liking them.


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## philddreamer

I bought some of these 9cm
http://www.ebay.com/itm/281084418614?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

and also some 102 medium flow, they work good! I like the price! 

Phil


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## Palladium

As my general filter i use the Double ring 102. Cheap, effective, and works for anything i need.


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## MarcoP

While looking into buying proper filters I came to decide whatever or not use gravity or vacuum filtering.
Gravity needs bigger and expensive filters while processing less solution, vacuums' can be smaller but process more solution. Vacuum wins in the long run.

Nevertheless, I'll be using gravity for now but it is getting really hard and somewhat frustrating, for me as newbie, to find a cheap match for Whatman #4, #5 and #598 grade! U.S. shipping to Italy is way to expensive, in Italy prices are high already and very few international fleabuy sellers adds μm sizes, filtering speed and use unknown brands each using different #Ns.

Thinking ahead: one think that puzzles me is how do you, practically, remove the filter from the buchner when the vacuum filtering is done and PMs' powder is caught in the filter. Do you tilt it? Do you lift it using your fingers?


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## goldsilverpro

> Thinking ahead: one think that puzzles me is how do you, practically, remove the filter from the buchner when the vacuum filtering is done and PMs' powder is caught in the filter. Do you tilt it? Do you lift it using your fingers?


Always break the vacuum before turning off the pump or attempting to loosen the paper. This can be done by disconnecting the hose.

With the pump still running, you can dry the powder in the funnel by placing about a 60 watt incandescent light bulb (if you can still find one) above the funnel. The vacuum will then suck hot air though the filter cake. This is tricky because, if the bulb is too close, it will char the paper and produce a mess. I would first try it with the bulb at least 10"-12" above the funnel. If it's not drying fast enough, lower it slightly. When dry, break the vacuum and the dry paper will be loose.


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## MarcoP

That would have taken me hundreds of filterings before, maybe even not, coming up with that idea, thank you!


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## Palladium

I use a stainless steel X-acto knife to reach down in the funnel and lift the edge of the paper lose while tilting the funnel sideways. Once you get an edge turned up you can use the point of the blade to drag the dried filter paper right off the bottom of the funnel and slide it right where you want it to go without touching the paper filter.


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## goldsilverpro

Since I discovered the stainless steel "Scoopula" about 40 years ago, I have always had 4 or 5 of them laying around the lab and one in my lab coat pocket. They have many uses, one of which is raising the edges of filter papers in a vacuum funnel. They are great for breaking up clumped-up chemicals. They are also about the best thing for transferring dry chemicals to a scale or a beaker. Wooden handles are available but I didn't have much use for them. Scoopulas are cheap. I found one place on the internet where they are selling for $1.60 each (see 2nd link below). Most places want $3 or $4.

https://www.google.com/search?q=scoopula+use&sa=X&biw=1252&bih=507&tbm=isch&tbo=u&source=univ&ei=L80HVMzpMIjEggSnpILgBg&ved=0CF0QsAQ

http://www.sciencecompany.com/Scoopula-Stainless-Steel-6-inch-P16134.aspx


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## Palladium

Well i'll be darn! Seems like every time i think i've learned it all, up jumps something new. 
The Scoopula ! :twisted: 
I've got to have one if for nothing else curiosity!


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## FrugalRefiner

I've been using one for years. I just didn't know it was called a scoopula.  

Dave


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## Gratilla

I use IndoMaret (a local ubiquitous 7-11 type chain) own brand paper hand towels, _tisu handuk_; 150 sheets, less than $1. Each sheet I cut to size and pop (smooth side up, dimple side down) into a kitchen plastic mesh tea strainer/flour sifter; three sizes (less than $1 each), one for each of my 250, 500, 1000 ml pyrex beakers. When the base of the filter is clogged, liquid can still filter out via the sides. 

Although scraping sediment off wet (thin) paper is risky, I drop the combo onto a sheet of newspaper and let it dry out. No problem.

This low tech solution was originally a matter of necessity, but it works great and I have no incentive to move over to a more expensive solution.


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## nickton

It looks like one could almost make a scoopula out of a pipe, using a peanut grinder perhaps, if one was like me, and rather cheap. The stainless steel however might make this too difficult of course. :idea:


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