I am trying to formulate a new water based white printing ink for
textiles.  I am having trouble reaching decent opacity without way to
high TiO2 loads.  Thus making it impractical.  I believe rheology is
the issue.  Achieving a good surfcae film may  help.  This should be
old technology that is contained in an old textbook.

Hello,
Have you checked the dispersion level of your TiO2? You will get
significantly more opacity from a well dispersed TiO2 (more pigment
surface area). How does it look on a grind gauge or a microscope
slide?

I dont know what printing process you are using (screen, flexo,
gravure inkjet etc.) but if your ink is too thin (and the textile
absorbant) the surface ink film will be poor. A well dispersed ink
will be slightly more viscous than a poorly dispersed ink. If simple
low viscosity is the issue, raising the resin levels is an option (but
obviously carries a cost).

I am an Ink Technologist and if dispersion is the issue, I can
definitely help you out with some dispersion tips and techniques if
you give me some more info:

What dispersion technique are you using (stirrer, beadmill, Three roll
mill, eigermill?)

What is the printing process (flexo, gravure, Paintbrush??)

What pigment loading are you using and are you dispersing at that
formulation or a higher pigmentation?

Give me some more info and I'll be glad to try and help you.