Por-15 on roof
Second vote for Ospho. I have been using it for 20 years. I saw them using it on a tugboat and asked about it. They gave me a 5 gallon bucket of it and I have been hooked since. There are MANY similar products with phosphoric acid and they all work but I havent found anything that works as well as ospho.
The biggest tip I can give you with using ospho is to keep it wet while its working and then wipe it completely off before it drys. If not you will get a white coating that needs to be removed. I still reccomend a good scuff prior to prime but its much easier if you wipe it clean before it drys.
Second vote for Ospho. I have been using it for 20 years. I saw them using it on a tugboat and asked about it. They gave me a 5 gallon bucket of it and I have been hooked since. There are MANY similar products with phosphoric acid and they all work but I havent found anything that works as well as ospho.
The biggest tip I can give you with using ospho is to keep it wet while its working and then wipe it completely off before it drys. If not you will get a white coating that needs to be removed. I still reccomend a good scuff prior to prime but its much easier if you wipe it clean before it drys.
