There should be a colour/life indicator somewhere on the cartridge that changes colour with exposure to the chemicals you are trying to filter out. It's kind of like reading litmus paper, so you can choose how far along the filtration cycle is good for you. I usually toss mine at about the 75% used mark.

https://www.3m.com/3M/en_US/worker-h...por-cartridge/

Thanks for pointing that out, I was not aware of those markers.

AFAIK, nobody rates their cartridges for use with isocyanates so I feel like they wouldn't put detection strips on it for that. However, from what I read after this thread started, they stop working for VOC before they stop working for isocyanates, so maybe it's okay. Take that as internet wisdom though, wasn't from an authoritative source My asthma annoys me enough that I'm not taking risks with something like that, as enticing as the thought of saving $400 might be

I'm fortunate to live in a climate that's agreeable for painting outdoors. I set up some plastic screens on one side of my patio and have at it. There is lots of venting and airflow. When shooting the clear when my head may be in the overspray, I hold my breath and get in there and spray fast and then I back off. I use a charcoal mask, not a fresh air setup. I've spent some time in automotive paint shops and have seen them shoot small panel repairs using just a charcoal mask on their downdraft primer area. I questioned this and they said it meets their safety requirements. Anyway, as just an occasional user this is what I do. I don't recommend this for anyone else of course, just sharing a data point and my reasoning.

I know it's been awhile but I finally painted my bike and it went nowhere near according to plan. After pricing automotive paint and then proper respirators I decided to use bike enamel. Then the bike enamel site didn't have some of the paints I wanted and I didn't want to wait. I ended up using Rustoleum Professional Enamel in rattle cans. Since I was doing a couple of different colors, I sprayed the grey first then the blue then finally the green. When I thought I was done with color, I went to spray non-professional Rustoleum clear enamel and the color immediately started to crack and bubble - the paint guy at Home Depot was wrong, they don't work together. Luckily I saw the bubbling quickly and stopped. I re-sanded those areas and resprayed the color.

Overall, even though it looks nothing like I originally imagined, I'm happy with how it came out. It's still really a 5' paint job but I'm fine with that. If I ever build another frame, I'll put more effort into the paint.

Mistake post.

https://cimg8.ibsrv.net/gimg/bikefor...bd5234b972.jpg
And here's a pic. Again, if you don't look too closely it doesn't look bad.

GC- Even if I squint I can still see the colors and pattern:)

While not my cup of tea I'm glad you're good with both the work and the results. My next frame will go against my better judgment and get PCed due to cost and how it will get used. Andy

Well, if I do another frame it will likely be Ti so I won't paint at all. If I do a steel frame, realistically there's a good chance I'd have it powder coated. At least I'd look long and hard into that option.

On bare steel you can give it a hcl wipe down . This will quickly remove carbon, rust in varing degrees of severity. Just rinse with very cold water and dry quickly. A great source of weak hcl is toilet bowl cleaner get the watery stuff not the gel or thick versions snobowl is what I was taught on. We would clean all our tubes, lugs and fittings in it before brazing. Just do not leave parts in too long or they will get eaten by the acid. This was a hand me trick from one of my predecessors and the great grandfather of a few of us MN frame builders Cecil Behringer

HCl may be fine for steel cleanup before brazing but I wouldn't use it before paint without neutralizing. Phosphoric acid on the other hand is a good option.

Some great advice here!