Lubricity of Soaps & Creams

[sanookd]

A lot of posters make reference to the slickness of a soap or cream but is there any way to scientifically measure the lubricity of a given soap/cream? Without scientific measurements or data isn’t slickness just ones subjective opinion?
Not being a chemist, scientist or other lab rat I’m just curious why one finds a given soap/cream slicker than someone else.

 

[Atlantic59]

A lot of posters make reference to the slickness of a soap or cream but is there any way to scientifically measure the lubricity of a given soap/cream? Without scientific measurements or data isn’t slickness just ones subjective opinion?
Not being a chemist, scientist or other lab rat I’m just curious why one finds a given soap/cream slicker than someone else.

Hypothetically, a test machine could be build. The problem is there are too many inter-related factors you would have to keep constant if you wanted to do any objective comparison. One standard razor, one standard blade, one standard surface to be shaved, one standard shaving angle, etc.

Then, there is the problem that the slickness comes from the lather, not the soap or cream. The lather has to be mixed with the optimal ratio of soap:water, has to be applied in a standard thickness, etc. Which leads to having a standard water of a standard hardness, standard temperature, etc.

So, now we have our hypothetical machine, with a strain gauge telling us the amount of force required to pull our standard razor across our standard surface, with our standard blade. We find it requires 0.52659319 Newtons of force. Does that help me as a shaver? The only thing that would really be useful for is to rank soaps and creams in some sort of slickness scale.

Subjectivity rules in DE shaving. All I care about really is that the lather I'm using is slick enough for me with my equipment and technique. Would a soap with 0.5349345 slickness be better? Maybe yes, maybe no. Slickness is not the only thing I value in a lathering product.

 

[Mar1978]

I’m pretty convinced that the quality of one’s water significantly plays a role in the slickness of the lather. Also, it can be the mix itself and how much product and water is used to make the lather coupled with the water quality which can effect the slickness factor.

 

[Cumberland Sausage]

The slickest soap wouldn't necessarily be the best. Too much lubrication might be a bad thing, or it simply might not matter past a certain point. Also, one person might like lather which is quite thick (as seen in many shaving videos) and so probably isn't optimal for slickness, while another will go for a more runny and smooth lather. I think there are too many factors at play and too much personal preference to be scientific about it.

 

[Steve56]

The slickest soap wouldn't necessarily be the best. Too much lubrication might be a bad thing, or it simply might not matter past a certain point. Also, one person might like lather which is quite thick (as seen in many shaving videos) and so probably isn't optimal for slickness, while another will go for a more runny and smooth lather. I think there are too many factors at play and too much personal preference to be scientific about it.

It depends on what razor that you’re shaving with. If you are a straight razor user, there is no such thing as ’too slick’. DE/SE users may prefer a little more film strength from their lather at the expense of slickness.

 

[BudgetShaverGuy]

Nope, have never seen any hard measurements myself. Problem is that, even a seasoned latherer with the best of intentions, probably wouldn't be able to get a repeatable measurement anyways. The lathers' quality and ultimate slickness would depend on the product quantity, water quality/quantity, lather time and the brush which makes it a whole new level of difficultly altogether....I personally have found many indicators of ultimate slickness come from the ingredient list. Everything I've tried with Tallow as the main ingredient has been the slickest of them all, but that's purely subjective, I have no numbers to prove it.

 

[Steve56]

Nope, have never seen any hard measurements myself. Problem is that, even a seasoned latherer with the best of intentions, probably wouldn't be able to get a repeatable measurement anyways. The lathers' quality and ultimate slickness would depend on the product quantity, water quality/quantity, lather time and the brush which makes it a whole new level of difficultly altogether....I personally have found many indicators of ultimate slickness come from the ingredient list. Everything I've tried with Tallow as the main ingredient has been the slickest of them all, but that's purely subjective, I have no numbers to prove it.

Don’t overlook that ‘brush’ part. A good brush makes a noticeably better lather than a not-so-good brush.

 

[BudgetShaverGuy]

Don’t overlook that ‘brush’ part. A good brush makes a noticeably better lather than a not-so-good brush.

I thought I covered that with:

.....and the brush which makes it a whole new level of difficultly altogether......

 

[nemo]

... is there any way to scientifically measure the lubricity of a given soap/cream? Without scientific measurements or data isn’t slickness just ones subjective opinion?

There are simple surface to surface friction and drag tests one could perform. Once you overcome static friction you could measure the force needed to pull a weighted block across a plate of similar material, or the angle when an object begins to slide. You'd need to standardize the viscosity of the soap or cream slurry. Old retired hydraulic civil engineering guy here. Lubricity tests I've run measured a wear scar, a destructive test using oils.

But where would the fun be in that? This site and most posts are opinion based, just ask a question and see all the different non-scientific answers you'll receive!

 

[Scarry Knight]

As far as I know there are just two standards of slickness...
slicker than snot on a glass door knob, and sliding around like spit on a hot griddle. All soaps or creams should fall to one side or the other of either of these.

 

[sarimento1]

As far as I know there are just two standards of slickness...
slicker than snot on a glass door knob, and sliding around like spit on a hot griddle. All soaps or creams should fall to one side or the other of either of these.

latter has been scientifically studied! Check out Prof. Leidenfrost!

 

[johnwick]

Our old friend Grant [mention]ShavingByTheNumbers [/mention] might know a thing or two about this topic!

 

[sanookd]

There are simple surface to surface friction and drag tests one could perform. Once you overcome static friction you could measure the force needed to pull a weighted block across a plate of similar material, or the angle when an object begins to slide. You'd need to standardize the viscosity of the soap or cream slurry. Old retired hydraulic civil engineering guy here. Lubricity tests I've run measured a wear scar, a destructive test using oils.

But where would the fun be in that? This site and most posts are opinion based, just ask a question and see all the different non-scientific answers you'll receive!

I get that , that’s why I posed the question if there would be a scientific way to prove one soap is slicker then another besides just reading one’s subjective opinion.

 

[kingfisher]

Our old friend Grant [mention]ShavingByTheNumbers [/mention] might know a thing or two about this topic!

I haven't seen a post by him in quite some time.

 

[zenex]

Forget about the scientifically measurement of soap slickness (in fact lather slickness). This is subjective, an YMMV thing. For example, a lot of people here - probably a large majority - find that Tabac soap is very slick, but not me. Personally, I find a lack of slickness in this particular cause. Rubbing the lather in your palms is one thing, the feeling of shaving with that lather can be a little different.

 

[old_school]

While relatively subjective a fella can still devise a method to learn something I suppose. Same gear using a rather subjective but uniform technique. Hydrate until the point lather shows a sheen and have at it. Almost any soap will talk to you at this point, some may need a little more libation to show well. If they don't have it by then it is what it is. Subsequent tests adjust hydration to your preferred consistency for evaluation.

 

[BudgetShaverGuy]

Forget about the scientifically measurement of soap slickness (in fact lather slickness). This is subjective, an YMMV thing. For example, a lot of people here - probably a large majority - find that Tabac soap is very slick, but not me. Personally, I find a lack of slickness in this particular cause. Rubbing the lather in your palms is one thing, the feeling of shaving with that lather can be a little different.

Tabac definitely has a tendency to get sticky if over-loaded and/or under-hydrated but I agree, it's not the slickest soap out there. Arko is definitely much slicker and much harder to screw up.

 

[FarmerTan]

As far as I know there are just two standards of slickness...
slicker than snot on a glass door knob, and sliding around like spit on a hot griddle. All soaps or creams should fall to one side or the other of either of these.

Gentlemen, I move that we adjourn.

We have the scientific answer we need.

Thank you @Scarry Knight for your help in getting to the answer we all needed to hear!

Now for the obvious answer to the question of which soap has the greatest lubricity for the price:

ARKO!

I move that me, @Scarry Knight, and Capt @nemo form a committee to look into a cure for Covid 19. Send your tax deductible donations to my bank in the Cayman Islands....your cancelled cheque will be your receipt.

 

[FarmerTan]

Tabac definitely has a tendency to get sticky if over-loaded and/or under-hydrated but I agree, it's not the slickest soap out there. Arko is definitely much slicker and much harder to screw up.

You can join the committee too!

 

[FarmerTan]

I haven't seen a post by him in quite some time.

I was conversatin' with him just the other day, Monday I believe.