Hello there.
What equipment do you use? What else does you formula has apart of ceteareth-25 and water? Do you mix the phases separately?
I came across the same problem some time ago, but I had success by:
-switching ceteareth-25 to cetearerh-20. I found that the ceteareth-25 had a tendency to foam more then it’s smaller chain counterpart.
-Mixing the water phase and emulgator phase separately, then adding ceteareth phase in water phase. Also, the temperature needs to be adjusted so it doesn’t go to high, as that can create bubbles also.
-avoid using PEG-7 glyceryl cocoate and PEG-40 HCO in larger amounts (more then 3 to 5% respectively).
-when adding ceteareth into the hot water, add it in portions.
-do not mix on higher rpm, and use an overhead mixer at maximum 200rpm (depends on the batch size of course)
-adding some glycerin and propylene glycol into the formula, if you haven’t can help
-after the mixing of phases mix slowly, then setting the rpm higher as it cools down slowly. Some bubbles have to occur in the process, it’s unavoidable. Use vacuum pump if you have the resources and remove excess bubbles formed after the initial mixing of two phases.
-preferably use a stirrer with axial flow
Hope it helps. It would be beneficial to post the formula and process of making the product also, that way you can get full help here.