Safe Flo 8 oz. Lead-Free Silver Solder Wire

yes

By Law, less than 0.20% or 0.002 (two parts per thousand) for the solder: Manufacturers will probably stay under that limit by a significant margin to avoid lawsuits and liability. The Safe Drinking Water Act (SDWA) has reduced the maximum allowable lead content -- that is, content that is considered "lead-free" -- to be a weighted average of 0.25 percent calculated across the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures and 0.2 percent for solder and flux. Compared to the old 60/40 lead tin solder, that is a reduction of the lead content by 300 times less lead.

Unfortunately, diameter of this Solder is not specified - it is a .117" gauge.

yes

You could use this, however, you will need to remove all paint and any rust down to bare metal. You will need to use flux and a propane torch.

Let's do the math... 95.5% Tin, 3% Copper, 1% Bismuth.. that adds up to 99.5% of everything except Silver. So, it must be about .5% Silver, or maybe a touch less.

For refrigeration or A/C, use only Stay Brite® 8 by Harris. It contains 6% silver and is very strong.

The solder gauge is a bit thick for small spaces, but if you're careful, it should be fine. It does, however, work great for instrument and audio cable.

less than 2% silver content.

This product is not suitable for aluminum.