What level of protection is needed for spraying caustic soda?
We are going to be dipping animal pens in a 3% solution and will be spraying it on farm premises.
I would recommend at minimum:
Chemical splash goggles
Chemical resistant gloves (I'd suggest reusable nitrile gloves, but heavy-duty latex gloves will also work)
Rubber / Waterproof boots
Keep the area well ventilated. If you can't do so, you will need to wear a full-face respirator with P100 (magenta) cartridges.
Also, if you are using a high-pressure power washer, wearing waterproof coveralls would recommend.