Defoamers / Anti-sudsing agents?

[sudsmaster]

Paulo,

Actually, surfactants work by lowering the surface tension, not by raising it.

It's certainly possible that by adding more detergent until I get a thin layer (really, more a suggestion of a thin layer) of suds I'm actually titrating for something other than surfactant, such as builder. However, it is certainly also possible that the oil in the cutting fluid is binding up all the surfactant in the detergent, resulting in lower cleaning effectiveness, until enough surfactant is added to overcome this effect and in the process produce some suds.

Here's a good discussion of surfactants:

http://www.scienceinthebox.com/en_UK/glossary/surfactants_en.html

 

[sudsmaster]

And here's a good discussion of builders:

http://www.scienceinthebox.com/en_UK/glossary/builders_en.html

 

[earthling177]

Rich said: Actually, surfactants work by lowering the surface tension, not by raising it.

Yes, I know that many do, sorry about the mangled statement I wrote. What I meant to say, is that when we use detergents that produce foam, the foam suppressants raise the surface tension to kill the foam. But that makes me wonder about the detergents that do not produce suds -- do they work mostly by just binding the dirt, perhaps, or maybe they just got foam suppressants on steroids?

 

[sudsmaster]

Paulo,

I'm not sure I would agree that foam supressants work by raising surface tension. That would be counterproductive to the main reason why detergents contain surfactants in the first place, wouldn't it?

From what I gather, sudsing is somewhat independent of a surfactant's ability to lower surface tension. That is, the sudsing level is dependent upon the chain length, branching, head polarity, etc. Then there are things called "suds stabilizers" which act to prolong sudsing (probably popular in hand dishwashing liquids like Dawn).

 

[earthling177]

Rich, yes, I understand what you are saying and I share the feeling. Still, what I read long ago on the subject of foam suppressants, particularly the cheaper ones, was that they operate exactly like that -- they float to the surface of the wash solution and raise the surface tension there in a layer a few molecules deep. As such, they tend to (a) work better in toploading washers instead of frontloading washers where the "top" of the wash solution is more diffused and (b) work better during the washing than during spin, for the same reason, so they don't prevent suds lock as well. I will be the first one to admit that it's been at least 20 years or so that I've read on the subject, so I may be getting things wrong.

 

[sudsmaster]

Paulo,

In my web surfing I did see some reference to the effect that some suds suppressors work better in wash vs. rinse, and vice verse. I also noted that anionic surfactants tend to be high sudsers, while nonionic ones tend to be lower sudsing (or so it seemed from my reading).

With reference to a previous discussion, the scienceinthebox website has an article on natural oil and fat based vs petro based surfactants. Basically, they are all synthetic, but common practice is to refer to the petro based ones as synthetic and the other ones as "oleo-based". We've seen some detergents that advertise themselves as having "plant-based soap". In any case, the structures are very similar, except that there is less range of choice in surfactants with the oleo-based ones, so the detergent mfg's like to use petro based ones instead of or in addition to the oleos.

 

[mayken4now]

I am sold on the Amway defoamer. Gonna try to get some.

Steve

 

[launderess]

Following was taken from a patent on laundry detergent regarding suds suppressors:

"Suds suppressors are represented by materials of the silicone, wax, vegetable and hydrocarbon oil and phosphate ester varieties. Suitable silicone suds controlling agents include polydimethylsiloxanes having a molecular weight in the range from about 200 to about 200,000 and a kinematic viscosity in the range from about 20 to about 2,000,000 mm2 / s, preferably from about 3000 to about 30,000 mm2 / s, and mixtures of siloxanes and hydrophobic silanated (preferably trimethylsilanated) silica having a particle size in the range from about 10 millimicrons to about 20 millimicrons and a specific surface area above about 50 m2 /g. Suitable waxes include microcrystalline waxes having a melting point in the range from about 65° C. to about 100° C., a molecular weight in the range from about 4000-1000, and a penetration value of at least 6, measured at 77° C. by ASTM-D1321, and also paraffin waxes, synthetic waxes and natural waxes. Suitable phosphate esters include mono- and/or di-C16 -C.sub. 22 alkyl or alkenyl phosphate esters, and the corresponding mono- and/or di alkyl or alkenyl ether phosphates containing up to 6 ethoxy groups per molecule. "

The above explains why all and manner of substances we have discussed here (soap,fabric softeners, oils,silicone, etc), work well keeping foam in check.

L.

 

[earthling177]

Results, so far

Recently I've bought some spa defoamer (ProTeam Foam Fighter) and have been testing it.

So far, it shows promise, it has cut down sudsing both during the wash cycle and the spin. Mostly due to curiosity, I have added it about 10 minutes into the wash cycle so I can check the level of suds there would be without any anti-sudsing agents, and the cleaning has been good -- however, I intend to test also adding the defoamer at the start of the cycle to see if it cleaning is impaired in any way. I've been using about half to a teaspoon of the defoamer per load, depending on how much sudsing I observe. I also intend to test it with different load sizes to see if there is any change in performance, as the loads I've tested have all been full loads.

In any case, yes, if you've been unhappy with the current selection of HE detergents, or for whatever reason you'd prefer to use a "regular" detergent, give this a try.

And I'd also like to thank y'all for your help!