White Pigment Question

Titaninum dioxide?

Lead-oxide perhaps?

"...white lead, heavy, white substance, poisonous, insoluble in water, extensively used as a white pigment and base in paints. It is one of the oldest paint pigments used by humans. Chemically, it is basic lead carbonate, a mixture of lead carbonate and lead hydroxide. It is prepared in various ways. When used in paints, it is first ground into a fine powder and mixed with linseed oil. Its covering power is greater than that of most other white pigments, but its use has certain disadvantages. It reacts with hydrogen sulfide and some other sulfur compounds in the atmosphere, the lead combining with the sulfur to form lead sulfide, a dark substance. In paints made with white lead a chalky film is formed after some time. White lead is extremely poisonous, and painters who apply it are often afflicted with painter's colic (see lead poisoning) because of the absorption of too great a quantity into the body. White lead is used also in making putty and in the manufacture of certain pottery. Sublimed white lead is the basic sulfate of lead mixed with lead oxide and zinc oxide; it is also used as a white pigment. White lead is often adulterated with barite...."

- Source:

http://www.answers.com/topic/white-lead

Check the ingredent list on a bottle of Tide washing detergent. It contains a lot of chemicals that look really white and bright under UV light.

That's true, Vermin. But these (e.g., Tide) ingredients are not pigments, they are fluorescent compounds. Fluorescent compounds typically absorb photons in the UV spectra, and re-radiate the photon at a longer wavelength, typically in the visible spectrum. Obviously, there is an energy difference, and that difference is radiated as heat. Note that when you wear, for example a white T-shirt that has been washed with a fluorescent-containing soap/detergent, you're T-shirt becomes ultra-white in black light. However, there are a number of inorganic materials (pigments) such as calcium fluorite, that also fluoresce.

Point taken.

"Even when you don't boil-wash."

They do not refect uv they absorb and transorm into vis region of spectrum.

please note that comercial titaniunm dioxide acts as a catalyser when exposed to UV light. It loses one electron from the valence layer to the conductivity layer and may degrade any organic substance.

It this is the case you should utilize silica wrapped TIO2 (Dow is one of the makers ).

Wish you success

Isn't the silica wrapping for the TiO2 absorptive in the UV? If so, although that would sort the catalysing effect, it would be at the expense of UV reflection.

Please say what you mean by pigmentation value in this context. Do you mean simply that it will be highly reflective in the visible, or that it must also accept a range of pigments? Also, what is the application...

For high-performance systems (integrating spheres, etc), one approach that has been used is to use a UV scattering layer above an optical layer. Depending on performance requirements, the UV layer might be CaF2 or LiF, which I believe have relatively low absorption above 200-nm, but unfortunately have low refractive indices and so need relatively large particles and thick layers to be useful optical scatterers. That is why ultrafine TiO2 is often recommended, as its higher absorption in the UV is offset by its high refractive index. The background layer for the optical region could be TiO2 or MgO according to convenience.

Fyz