Pastes Behaving Differently With Different Blades

[mjclark]

With straights, I much prefer the finish from chromium oxide to ferric oxide. The crox gives smooth and keen results but the feox, although finer, gives an edge which to me seems harsh and brittle.
I've also been stropping proprietary Rolls razor, Wilkinson Empire and GEM SE blades on their appropriate automatic stroppers with their appropriate strops, and with them the pastes behave differently.
In this case the crox seems too harsh and it's the feox which gives a nice polish.

Any suggestions why the pastes are giving such different results for straights and SEs?

Is it simply because with the straights the paste is on balsa, whereas with the SEs its on leather so has more give, like the damp paper smoothing lapping film edges?
This is probably contributory, but doesn't explain why the SE blades don't like chromium oxide.
What do you think?

 

[Gamma]

I dont know that youll ever get an answer, but to compare accurately you'll need to hone both types of blades/ edges on both substrates with both abrasives. Different substrares change the game significantly.

 

[HonerSimpson]

I've done a fair bit of experimenting with pasted stropping and consistently found the results to be inconsistent.
My own explanation is that a foil edge is easy to produce with the abrasive-loaded strop. With that in mind, I use a procedure where I sharpen, smooth (remove the foil) and then sharpen again (eg 30 on .25 diamond,30 on 0.1 CBN, 10 on 0.25 diamond).
It seems logical that the bevel angle will be a determining factor and also, as you mention, whether the strop is compressible or not.
Any idea what the bevel angles are on your Straights and SE blades?

 

[Alum of Potash]

Interesting point about the substrates affecting things. I always considered them neutral, when they may not be. Lots of variables here, but I've had good results using ferox on hanging leather.

 

[Gamma]

Ironing out the variables is nearly impossible. Whats important though, is that any abrasive can behave differently due to changes in pressure and the substrate can play into the equation at what I call the user level.
How tight a hanging linen is held can affect how the user gets the edge 'there' - it doesn't affect the abrasive, just the process.
Same for abrasive concentration.

 

[mjclark]

Great answers already!
I hadn't considered bevel angles but I'm pretty sure that the SE bevels are fatter than the straights.
This also confirms for me that honing is a lot like cooking - it's a lot of fun in a place where science meets art!

 

[RocketMan]

Great answers already!
I hadn't considered bevel angles but I'm pretty sure that the SE bevels are fatter than the straights.
This also confirms for me that honing is a lot like cooking - it's a lot of fun in a place where science meets art!

It can be a crapshoot with the SE blades and the pressure applied with the various Rolls, ER, Valet contraptions may well have a strong influence. It is certainly worth the experimentation though. The sources one uses for the powders may have a a lot of impact as well since it is difficult to determine the makeup of any particular vendors powders. It can depend on where they pick it up and whether or not the compounds are relatively pure. At times, a CrOx may have larger particles than an IronOx depending on the quality. There also seems to be a lot of variability in what grit people believe these powders to contain. It is definitely not an apples to apples kind of topic.

 

[mjclark]

The pressure issue is interesting too. Those automatic stroppers work almost perfectly with no pressure but the weight of the blade itself, and I guess this could be another factor.