How should I apply Red Iron Oxide for this effect?

[leopold 2]

Hi Everyone,

I would like to make some designs for this effect.  That's a new starting for me. 

I don't know what the real it is for that dots in the surface. Is that Red Iron Oxide? In Clay or In Glaze?

I fund a video from Youtube to tell me how to mix the clay with Red Iron Oxide, but it was not very clear, not shown the whole process. 
The recipe from that video is 25% red iron oxide and mix with red clay of 75%, my question is how to mix them? 

Thanks for any kind of help.

Edited March 16 by leopold

[Babs 899]

Those marks coming out of the clay body on firing

[liambesaw 1,550]

Granular magnetite, manganese or illmenite wedged into clay and fired in reduction will bleed these spots from the clay body.

[Sheryl Leigh 24]

On 3/15/2019 at 9:11 PM, liambesaw said:

Granular magnetite, manganese or illmenite wedged into clay and fired in reduction will bleed these spots from the clay body.

Ah, that's what illmenite is for!

 

[Babs 899]

Only if rough stuff.... ilmenite fine "sand "gives small speckles

 Havent seen it come as rough cut

[Rae Reich 395]

Granular Illmenite is coarse. That's what is used in some speckled glazes for that effect.