problems with yellow

[fourkbmx]

i've some great results using yellow and yellow mix but recently im having trouble with them, its taking to long for the dye to penetrate the oxide im not doing anything diferent from what ive done before 1mil, 20 min in the colour mix. but now i have to dip the piece for about 1hour or two if i want the same result.

[Empire03]

I believe your acid bath is low on acid.

[fourkbmx]

how can i measure the consentration of the bath?

[sswee]

Your problem with the dye time is proof of the need to keep notes on the parameters of your runs. What was the average tank temp when the parts dyed well as opposed to when they started to take longer to get the same color? Coating thickness and pore size effect the dye process. With all the variables, it's sometimes difficult to distinguish a problem with the coating from a problem with the dye. If you are still able to get the same color from the dye albeit a much longer dye time and you use the dye at the same temp then your problem should be from the coating. What has changed? I've run my tank for right at two years and had no problems with acid concentration. Most problems have been connections, temps, different material grades or miscalculating SA.
If you know or can figure out what has changed, it'll help diagnose the problem.
SS

[fourkbmx]

i dont think the problem is on the tank, because i didnt have any problems with other dyes, i havent change the system at all, im running the tank at the same temp, current density etc. my yellow dye seems a little cloudy, i dont know if that is normal, is the only one that looks like that

[sswee]

If that's the case. I would heat the dye to 180* like you do when you first mix it. Stir it up real good. Then strain with a coffee filter. The dyes seem to start to come out of solution after sitting unused for a while. I do this to mine if I haven't used the color for a while and it works for me.
SS

[fourkbmx]

thanks, i think this will be the case, because mine have been unused for a while