So I got a DJ (isn) frame and it came with a completely seized Al alloy seat post.
I dissolved this out (during the cold snap) and as best I could washed out the insides and then dried and added WD40 until the insides were dry before reassembly. Â Washing out was hit and miss due to sub zero temps... (no hosepipe)
Anyway, rebuilt quickly but now I'm getting NaOH coming out when I get water in the frame. Â Essentially it must have recrystalised in the colder sections inside the frame (like chain stays)
Obviously not the best for HSE ... but worse I'm worried its going to drop onto alloy components ...
I stripped it and washed it out again last weekend... dried and WD40.... squirted water in under pressure from garden hose against the drain holes in the seat stays and put a few gallons through the head tube and BB... until it started to run clean.
I'm thinking of re-flushing again before assembly... Â but anything better than boiling water ??? (and obviously not something that is bad for CrMo.... )
I could flush it with an acid but H2SO4 or even HCl might not be great for the steel.... and I have a fairly limited supply of these anyway... and I can probably no longer even buy more of the sulphuric (one shot)....
Dilute brick cleaner (HCl)? Or just flush again with the hosepipe.
Not HCl with steel. It'l never be the same again. I'd go for loads of water and if I really wanted an acid rinse maybe vinegar? Then loads more water
why not use hot water give how soluble NaOH.
I'd expected it to wash away pretty easily... as POAH say's its pretty soluble...
I just did hot water .... (as close to boiling as I could pyrex jug and boiling water) ... then flushed with a few gallons of warm (hosepipe) ...
Hopefully that will do the job....
I think the problem is/was it (now) some aluminium salts in it that makes it much less soluble... ?
Where its leaked out you'd expect it to wash away pretty easily but it really requires a bit of manual effort as well... but I'm guessing the whole thing now has (relatively) insoluble Aluminium hydroxides as well?
During the seat post dissolution it would have been super-saturated as it's strongly exothermic then pushed the supersaturated solution into colder parts along with the Aluminium ions... whilst Jnr and I had fun with the hydrogen 😀
