Anodizing Problem

[David Wesner]

I could use a hand on an anodizing problem I'm having.Heres the issue.My anodizer is a variac w/a R Shack 4 way bridge.My cathode is a 2"w x 6"L piece of .063 Ti wrapped in Tool Drawer liner.My anode is a piece of Ti bent into a hook shape screwed to an alligator clip and wrapped in elec tape w/a micarta grabber.Although the variac has an analog meter I have a digital volt meter hooked in also.My electrolyte is the standard 2 tbsb. of TSP to 1 Qt. of Distilled water.I have sucessfully anodized several other pieces of Ti since putting together the unit.Last night I was in the process of doing some liners and started out fine going thru the color spectrum to reach my desired color when the 5A fuse blew.No prob.,I replaced the fuse (after taking the liners out of the TSP solution) and started over again from 0 volts.The Ti refused to anodize and the color that was there disapeared.I cleaned up the liners w/acetone and jeweled the inside facing side of the liners with a cratex rod and cleaned again w/acetone.The jeweled side anodized beautifully but the other side of both liners wont do a thing.I dont have a theory about the blown fuse. I do think that the alligator clip touched the electrolyte and contaminated the electrolyte though (I changed the solution after jeweling)and like I said was sucessful in anodizing the jeweled side.Thru touching the solution w/ the clip and retrying with contaminated solution could I have coated the liners w something that is causing a block like nail polish or sharpie would acomplish?The reason I have come to this conclusion is that thru the jeweling process I theoretically cleaned the "block" off of one side while leaving the block on the other(the un-jeweled side).Has anyone else ever experienced anything like this before?Since the side that refuses to anodize will be covered w/G-10 I'm going to leave as is but would like any theories as to what happened here.BTW,I'm "positive" that the cathode & anode did not make contact during the process in case that would be someones answer to the problem.Just for the record too,the side that wont anodize has a dull gray appearance to it.I'm puzzled as to what happened and any answers will make me feel much better.Thanks,wez

 

[fitzo]

Doesn't Ti turn gray when the oxide is thickest, at the highest voltages?

 

[J. MacDonald]

Sounds like maybe you have clear ano on the non jeweled side, but I'm WAY too new at this to offer up more than just a wild guess.