Sunscreen formulating question

Hello everyone, 

I'm trying to play around with making a sunscreen. I'm not making it to sell or give away. I'm just trying to learn for my personal interest. I mixed up a batch that seem to be stable at 45C for 2 months, but I would like to see if I can improve how it was made. 

It's an o/w emulsion. 

Filters used:

BEMT Tinosorb S - 6%

BMDBM Avobenzone - 3% 

HMS Homosolate - 1% 

OCR Octocrylene - 10 % 

UV similator shows:

SPF - 34.1

UVA 17.7 - PA++++

PPD - 19.8

Real Life SPF - 30

I'm using Corapan as a UV stabilizer, and  copolymers+silicones as a film former. 

It is hard to find information on how the filters should be used. Currently, all the filter are mixed into the oil phase, and heated to 80C. Would heating the filters using the process degrade them? I've came across a formulation where they heated avobenzone to 80C , and I assumed it was safe to heat the others too. 

In addition, I have a small homogenizer and would like to some how use it to disperse the filters more. The issue is I'm using Gelmaker EMU, polymers and hydroexyethylcellulose which are sensitive to high shear. Would it be enough to use the homogenize on the filter when they are mixed into the oil phase, which is before any of the high shear sensitive ingredients are mixed in.  

It would be amazing if someone would direct me to some sources on how to use filters. 

Many thanks :) 
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