2 questions.
#1 if I'm hauling over 8,820lbs ( bulk ) I know that I need to put out my 1263 placard. My question is do I still need the placard that just says flammable?
#2. Do I need the bulk placard when I'm coming back with "empty" tanks that still have residual paint in them? Even though I don't have over 8,820 lbs. I know that I'll still have to put on my flammable cards. I may be over 8,820 pounds because the tanks weigh 500 lbs each, but the leftover paint inside doesn't weigh enough for a bulk placard.
I can't seen to find a clear answer. So in the mean time, I put out both placards.

 

I haven't pulled a chemical tanker or hauled any HazMat is some time(I still have my HM endorsement), so it took me awhile to research this answer.

#1 Your Hazard Class 3 bulk placard with the UN1263 marking is the all you need. Although it is good to properly mark a HazMat shipment, overmarking can attract undue attention. Plus, if one of the unneeded placard is lost or damaged, that could be a discrepancy in an inspection. Best to keep it simple(but correctly marked).
#2 The bulk placard has to do with the maximum capacity of the the packaging(eg. the tank), not the amount of the product in the package. So even thou there is a residual amount of paint left in the tank, the tanks capacity hasn't changed. The bulk placard has to remain on the tank until cleaned.

Bulk vs. Non-Bulk: Size matters

 

Thanks Danske