[labnetwork] H2SO4 and HF Delivery and Acceptance

Wed Sep 23 10:54:34 EDT 2026

While I don’t have much to add in terms of bottles, you may want to keep in mind that concentrated sulfuric acid is very hygroscopic and would happily suck out any moisture from the air.  So a small leak would naturally get diluted. For sulfuric, pH 0 can mean anything down to ~5%, or 20x dilution.

Mike

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Michael Yakimov
Research scientist
Department  of Nanoscale Science and Engineering
University at Albany - State University of NY

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From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Aaron Hryciw
Sent: Tuesday, September 22, 2026 18:00
To: Network Fab <labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] H2SO4 and HF Delivery and Acceptance

Hi all,

Just to add a datapoint, we have also seen this with sulfuric acid, not infrequently over the past few years (from both Fisher and VWR), but fortunately not with HF.  This is usually evident as soon as we open the boxes, seen as visible droplets of liquid on the bottles (usually sitting near the base of the handle) and/or drips on the sides or bottom of the cardboard boxes.  pH test strips on the drips yields a pH of 0, but the acid is not so concentrated as to immediately darken cleanroom wipes, as you would expect for 95% H₂SO₄, so it's a bit of a mystery.  We clean these bottles and place them in cabinets in our chemical stock room until they are brought into the cleanroom as needed.  While being stored in the stock room, some of bottles "reoffend", with similar drips showing up again days or weeks later, despite having sat undisturbed.

We have escalated this with the vendors, but still get at least a few (~5–10%) leaky bottles in most of our orders.  At this point, we're still not sure whether this points to a manufacturing defect particular lots of bottles and/or caps, damage during shipping, or something else.

Cheers,

 – Aaron

Aaron Hryciw, PhD, PEng (he/him)

Fabrication Group Manager

University of Alberta - nanoFAB

W1-060 ECERF Building

9107 - 116 Street

Edmonton, Alberta

Canada T6G 2V4 Ph: 780-940-7938<tel:(780)%20940-7938>
www.nanofab.ualberta.ca<http://www.nanofab.ualberta.ca/>

On Mon, 6 Jul 2026 at 09:30, Prashant Srinivasan <prashant at ucsb.edu<mailto:prashant at ucsb.edu>> wrote:

Kathy,

Could you elaborate a bit on the nature of the contamination? Appearance? Chemical composition? We purchase from Fisher Scientific and VWR.

If you are referring to crystals, especially in BHF, this is normal. The concentration of Ammonium Fluoride is very high, often near saturation and crystallization typically occurs when the temperature drops. If you see crystals around the cap, local evaporation is the likely cause. In either case, diluting slightly with DI water or bringing up the bottle to 23- 25 C should solve the issue. If you have a large amount of crystals, the chemical composition might have changed. It is hard to say without pictures.  Note that HF (not BHF) should not have crystals.

Prashant

On 7/2/2026 11:20 AM, Kathy Anderson wrote:
Hello Lab Network,

What is your lab's strategy to minimize the occurrence rate of receiving incoming boxes of H2SO4 or HF bottles with chemical contaminating the inside of the box and/or the outside of the bottles?

Do you have a preferred vendor or vendors you avoid for this reason?  We are experiencing this phenomenon sporadically from multiple vendors.  Some respond by wrapping their bottles or the rims of bottles before shipping for a time, but not indefinitely, and some are only willing to replace.

Kathy

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Kathy Anderson
Chemical Engineer III
Utah Nanofab
The University of Utah
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--

Prashant Srinivasan

Teaching Cleanroom Engineer

Electrical & Computer Engineering

Univ. of California Santa Barbara

https://www.ece.ucsb.edu/department-resources/electronics-shop/tcr
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