deadrush
Hazard to Self
Posts: 52
Registered: 3-3-2014
Location: Worcester MA
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Mood: Ecstatic
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Cleaning Glass Frits
There are many different methods used to clean frits. One older method uses a chromic acid solution (Chromerge etc.). However, this method should be
avoided as Cr(VI) is an environmental pollutant.
Avoid soaking your frits in a base bath solution. These eat away at the frit and can make it extremely brittle or even dissolve the frit itself!
Cleaning a frit has several basic steps. There are many variants of this procedure:
Remove all residues from the frit (Celite, precipitates etc.) and dispose of these in appropriate waste containers.
Scrub off any remaining residue with a brush or KimWipe, taking care not to damage the frit.
Clean the frit using appropriate solvents (water, acetone etc.) and vacuum filtration.
Soak the frit overnight in an appropriate cleaning solution. A good one is sulfuric acid/Nochromix . Always make sure that your cleaning solution is
compatible with the chemical residues on your frit!
Use vacuum filtration to wash the frit thoroughly with distilled water, dilute ammonium hydroxide (if you used acid) and distilled water.
Dry and use!
If a frit runs slowly or is still clogged after this cleaning procedure, you can try pulling a dilute HF solution through it or let it soak in a base
bath for several hours.
Boom! CAUTION: TAKE CARE NOT TO MIX INCOMPATIBLES DURING THE FRIT CLEANING PROCESS.
Do not pull acetone (or other organics) and sulfuric acid (or hydrogen peroxide) into the same filter flask. This mixture will explode and cause
serious injury or death. Always keep organics and acids separated during the cleaning process.
Always wear proper personal protective equipment such as goggles, a lab coat and apron when cleaning frits with acid. Accidents tend to happen most
commonly when you are "just cleaning up" and become lax about the possible dangers involved.
Some people use "piranha solution" (sulfuric acid + 30% hydrogen peroxide) to clean frits. This method is exceedingly dangerous and has resulted in
many serious laboratory accidents and injuries. Read this firsthand accident description (the last post in that document) and you will understand just
how dangerous it is. NEVER use it.
From: "https://www.ilpi.com/inorganic/glassware/frittedfunnel.html"
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bnull
National Hazard
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A jackass wrote once that "whatever you have that uses a glass frit, if it is clogged, try sucking water from both sides." The rationale was that the
particles and holes can act like small one-way valves: open to the flow in one direction, closed to a flow in the oposite direction. Forcing water
first into one end and then into the other loosens and removes the particles.
Edit: If what is clogging the frit is based on protein or fat, try a solution of urea and sodium carbonate. It is less corrosive to glass than
alkaline hydroxides and is quite fast in dissolving these organic residues.
[Edited on 13-12-2025 by bnull]
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Sulaiman
International Hazard
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a confusing post:
"Avoid soaking your frits in a base bath solution"
"try pulling a dilute HF solution through it or let it soak in a base bath for several hours."
you wrote to never use piranha solution ... But this is one of my favourite frit cleaners !
as you wrote, consider compatibility first.
(your cleaning solution SHOULD be incompatible* with the contaminants or it will not work !)
I know that there are risks with piranha solution, but I consider HF more hazardous.
* reacts with or dissolves
CAUTION : Hobby Chemist, not Professional or even Amateur
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j_sum1
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Thread Moved
13-12-2025 at 19:43 |
j_sum1
Administrator
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Registered: 4-10-2014
Location: Limbo
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Mood: Just got through yet another "take this job and shove it" moment.
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Slightly cynical here. So take it in the spirit intended.
One of my favourite methods is ignoring it.
I am always more worried about stuff I can see, that is, discolorations, than I am about stuff that is colorless or white pigmented.
I have spent time pullling acids or bases through the frit trying to move a stubborn stain, and having it not budge at all. But, if it is not coming
off, it is not going to critically contaminate anything I am working on - at least not at the level of precision I work at.
If I am really worried about clean glass, pirahna is my go-to.
I also have some ampoules of dirty chromic acid that I can use. Last foray in Cr chemistry, instead of reducing and precipitating my Cr(VI) waste, I
acidified it and bottled it up for glass cleaning. I have not had occasion to use it yet, but it us nicely stored and ready to go when needed.
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