Need respirator recommendations

Filters aren't cheap, and you need to keep them off the mask and in a bag when not in use. Use a good black/solvent with purple/HEPA filter. All fumes are bad, but the isocyanates are worst of all. The fresh air us the best, but not cheap. I've used both, and I've noticed with the fresh air that some coating would sneak in around. I sprayed heavy metals like chromate primers. Nothing better for corrosion protection but have issues also in how to dispose of waste.