BAQUACIL (27% HP)
I believe that I paid $15 for a gallon of Baquacil Shock and Oxidizer from my local pool supply shop. It is 27% HP.
I'm running three experiments with this. I bought several larger coins, which are more or less culls, but some hold promise.
BD
First, there's one coin that has BD. The reverse has some patina intact. The light green patches is BD, and you can see the pits that it is eating into the surface of the coin. I don't think there's much detail left of the coin itself, but it has BD- which I wanted to test.
This will be soaked in straight 27% HP. I took the before picture, and will use a pin to work on the BD, and use a nylon brush on it. There is a bit of dirt on the coin, and some orange encrustation.
Before: 4/03/06
4/7
I changed the solution on 4/5, letting each solution soak for two days.
All remnants of the BD has been removed.
After a brass and silver brushing:
Patina is still intact. The roughness was caused by the BD. Probing with a tungsten pin reveals bare metal, so this is sadly the best it will get.
I'm going to let the coin sit on my shelf for a couple weeks and see if the BD returns.
STRAIGHT BAQUACIL
These 5 coins will be soaked in straight 27% HP. The two coins on the top are crusties. The two coins below are what I call lightly dirty, and the coin on top of the other coins, in the middle, is what I called moderately soiled and/or lightly encrusted. The moderately soiled coin and one of the lightly soiled (bottom row, right) coins have the lightish green powdery patina, that can sometimes be removed with just a silver brush- so the patina may be removed on those two; no fault of the HP. You can see the loss of patina along the reverse edge on the lightly soiled coin already, before the test. They initially weigh 36.7 grams, and have not been presoaked in water or such- they are just as I received them.
Hopefully only 5 coins is below the point where this stuff reacts violently-
Before:
4/7
I changed the solution on 4/5, letting each solution soak for two days. Coins now weigh 36.5g, a loss of 0.2g. The green patinas have turned brown; at least at this stage.
After brass and silver brushing:
Coins now weigh 35.8 grams- that's a sizable loss. I worked on the encrustations a bit, and got these down to 35.55g. The TICA and multiple obverse countermarks coin is pretty much done after a little work, as well as the coin in the top left. It has metal spurring, which really can't be fixed safely.
I'll combine the three encrusted of this one, with the two left over from the 13.5%.
BAQUACIL- Roughly 13.5%
These are set up as the above picture, and are "fresh" coins as well. I roughly cut the Baquacil in half, by adding approximately 1/2 gallon Baquacil to a 1/2 gallon of distilled water. The only thing to note on these is that the bottom row, left coin has bare bronze showing in places- it looks like someone took a steel brush to it. Coins begin at 38.8 grams.
4/7
Solution was changed after 2 days as well. Weight loss is only 0.1 grams, at 38.7g. Green patinas have turned brownish as well.
After brass and silver brushing:
Coins now weigh 38.25 grams, another considerable loss in weight, simply by brushing. I was able to remove some encrustations and dirt- and what appears to be some rough silvering on the Avgvstvs... coins now weigh 37.5 mm. I'm going to continue to soak the two encrusted coins (top two in the above picture).
I'll try to remember to post pics of the other 3; they're near slugs, so I'm not going to spend much time on them. I think I'll just soak in alcohol, 3M and Microfiber and then Renwax them.
Four Finished Coins
The bare metal on the top right coin is from me working on the dark green encrustation. The bottom right coin is porous, but I think that the countermarks are authentic. The bottom left coin has what appears to be silvering mixed with green encrustation in spots. When removed, it leaves bare metal, so I left it. It's Augustus, but the reverse is slick. The top left coin has a copperish cast to it from the brass brush, I was unable to get the residue off... and since it has no details and is bent, I wasn't going to waste any more time on it.
STRAIGHT SOLUTION- Encrusted coins
The 5 encrusted coins of the above experiments weigh 39.8 grams. I'm going to soak them in straight Baquacil.