San mai finish problems, not an etching question?

Sorry for the bad pic, but it's the one that shows the problem the best. Those spots on the blade are not dust, it's clean. I've sanded way past any forging problems. The problem is in the 1084 core and the 15n20 cladding. They aren't just spots, they are very slightly pitted. I've done the same method without this issue. Wondering if anyone has seen this problem. I did forge close to shape, but I know I'm well past the decarb layer.
 
Sometimes when I use old ferric chloride, there are little things that float and stick to the blade, they leave tiny silver spots. The way I fix it is - I take out the blade and wetsand it with 2000 sandpaper, put it back and repeat 2-3 times. Sometimes if the solution has too much of these contaminations I just have to re polish and re etch in new clean solution.
 
Thats exactly what these look like. I'll give that a go. Thanks.
 
Well, I had to take it back to 600 but it's looking good now. Spots are gone. Weird, it looked like contaminated steel but I knew that couldn't be given it was in both steels. I wonder if there is a way to clean up my ferric chloride? It's a homemade batch and has worked well up until now.
 
If you make up ferric chloride from concentrated solution or solid, a precipitate will form upon dilution/dissolution. It is insoluble Ferric Hyrdoxide. You can try and filter it, or, easier, decant as best as possible. More precipitates will form with time from exposure to the gases in air, not to mention the oxides from the etch.
Carefully decant periodically or make fresh.
 
I made it with steel wool, hydrochloric acid and hydrogen peroxide. I couldn't find anything else. It's probably just getting old. I'll make a new batch.
 
nmbarta said:
I made it with steel wool, hydrochloric acid and hydrogen peroxide. I couldn't find anything else. It's probably just getting old. I'll make a new batch.
Click to expand...
My lab advice: make it in one container, allow a couple days to react and precipitate, then decant slowly into the final container.
 
I appreciate that. I'll slow everything down this time, I had a near melt down last time. Youtube isn't the best source for doing chemistry experiments in your basement. The exothermal reaction is real and happens really fast.
 
If you don't already know this: DO NOT keep hydrochloric acid in the shop or basement. Hydrochloric acid gas is about as pesky as anything that ever got out of a closed bottle. Unless you wax it shut every time, it'll rust your tools and machines.
Personally, if you don't have a chemistry fume hood in your basement 🤣 , I would do the initial reaction outside and leave the remaining acid in a clay tile back behind the shed.
 
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