Do not spray Gentoo without sufficient engineering ventilation controls or without making a minimum of supplied-air respirators available to all those exposed to Gentoo spray.
A list of supplies and equipment can be found at http://tinyurl.com/gentoofaq4. This list includes a supplied air respirator.
If engineering ventilation controls are not available or sufficient, wear a minimum of a hooded supplied-air respirator and nitrile gloves. A paint suit / Tyvek suit is recommended. Refer to Safety Data Sheets (SDSs) for both Part A and Part B before beginning to apply Gentoo.