Episode 49: An Interview with Darren Williams, Professor of Chemistry

Products Finishing recently hosted its Parts Cleaning Conference, co-located with IMTS 2024. In this episode of the podcast, PF Senior Editor Lori Beckman interviews conference co-chair, Darren Williams, professor of physical chemistry and leader of the cleaning research group at Sam Houston State University in Huntsville, Texas. The pair reflect on highlights from the 2024 conference and discuss industrial parts cleaning trends and current regulations.

PF: Were there any standout presentations for you this year?

DW: I really thought the presentation on CO₂ cleaning was an especially good one — it really went through a lot of the science behind CO₂ cleaning technology. Also, because I am a laser person — my background is in spectroscopy, the laser cleaning presentation was also something very interesting to me.

We had several presentations that focused on, or at least spent some time, discussing case studies that emphasize real world situations. I think that kind of information is especially helpful for attendees, because some of the scenarios hit home for them, making it easier to visualize what problems might occur and how to solve them.

PF: As a professor of chemistry and with your involvement with cleaning research, what are the trends that you’re seeing currently in the industrial cleaning industry?

DW: Currently, there’s still a trend to find out what we can replace trichloroethylene with. I often get inquiries about what I suggest in terms of a replacement for trend trans or trichloroethylene. And you know, there's not a lot of good answers in that. So, there is a trend of still trying to find drop-in replacements for open-top vapor degreasing. There’s still, I would say, a closing regulatory window or a narrowing window on n-propyl bromide (nPB). There's also these trans blends, trans one, two, and dichloroethylene (DCE). But the fluorinated compounds that we use to inert the flammability of trans DCE is also coming under regulatory scrutiny because they either are PFAs (perfluoroalkyl substances) or their precursors are, so they're going to be seeing some regulation in the future, I think.

So, there's a lot of uncertainty with solvent cleaning. That's definitely a trend. And then what that does is it moved them towards more equipment changes and process changes than just placing a new solvent in that existing piece of equipment.

PF: Regulations are an ongoing conversation in the cleaning space. We're always talking about that, and even at the parts cleaning conference, that's usually one of the hot topics. What can you say about the current regulatory climate?

DW: It’s pretty stormy with the regulations and tightening the exposure limits on trichloroethylene, nPB and some of the other solvents, perchloroethylene as well. There’s a lot pushing manufacturers toward changing their equipment to where there is absolutely no way for the solvent to go right into the atmosphere and impact the worker, so this is about worker safety. These sealed systems and closed systems are probably the future.

This is what has been happening in Europe for many years. We can benefit from a lot of their best practices. There are a lot of companies in Europe that are wanting to join forces or move into the U.S. market.

There are a lot of options for closed cleaning machines. But they are very expensive, so you may need to plan for a large capital expenditure and some of these other solvents, the trans blends, if you’re doing vapor degreasing might enable you to plan, but you’ve got to plan during that time. If you make a change in your process, you’ve got to use that time that you’ve bought to plan for a capital expenditure if you’re going to be switching processes to a closed machine.

PF: Tell us more about the PFAS regulations and what’s happening with that.

DW: Yes, so 3M shocked the world about 18 months ago, when the company exited the market without any warning on its PFAS solvents and their fluorinated compounds. It decided to drop that whole product line and will stop shipping those fluids in 2025.

There were a lot of blends that had the trans one two dichloroethylene in them. And that is a really good solvent for cleaning, but it's flammable, and so for open- top vapor degreasers, you have to not have a flammable solvent in there. So, they made a lot of azeotropes with these fluorinated compounds that acted as a fire retardant. That’s the way I describe it.

Now it’s not just the solvent that’s being regulated, but the fire retardant is being regulated as well. This doesn’t only hit 3M because the ones they have the most toxicological data on are the perfluoro octanol. So, it’s an alcohol that has fluorines on it, and then the acid version of that, octanoic acid. So it’s carbons with an acid group on it. But all the hydrogens have been removed from the organic piece, and fluorines have been put on, so those are precursors to a lot of the fluorinated solvents. And so, if the precursors are regulated, then the costs and possibly availability of all those fluorinated solvents is in jeopardy.

Therefore, this is not just a 3M issue. It's any of those fluorinated substances might come under regulatory scrutiny. And so this is or just if they regulate the precursors, then those solvents might become unavailable or prohibitively expensive.

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Listen to the complete interview in an episode of PF’s On the Line Podcast: short.pfonline.com/OTL49.