Help please I am going crazy!

[jagrc]

Hey everybody,

I am new to the anodizing world. Over the last week we have been experimenting with a system we put together. I'll give you a quick rundown of the system;


we have 4, 3 gallon plastic tanks. The first has a mixture of 3 gallons of DI water to 1 gallon of battery acid. The acide tank is using a 10" x 1/2" lead plate with 2 12-14 gauge aluminum wires attached to it. the next tank is straight DI water. The next tank is Caswell die (green and yellow) then there is another DI tank and finally a tank of boiling DI water (This tank is metal)

We are using a 12v battery charger wired through a dimmer switch to power the anidizing process.

Having said that here is what I am fighting, I figured a part to be about 4 sq inches so I set the charger to 120 MA I let it anodize for about 90-95 minutes. I pulled the part out of the acid bath, rinsed it and placed it in the dye. The part sat in the dye tank (110-160 degrees) for about 20-25 minutes. It came out a very rich dark green. I then rinsed again and put in a pot of water heated to a rolling boil. After 15 minutes in the pot I removed the part to find it a pale green. All the dye had leached out. Can anybody here give me some tips on what I am doing wrong here

[whistule]

If I leave drops of water on an anodised and dyed part (before sealing) then I find that the dye leaches out leaving lighter stains where the droplets were. Obviously your problem is the dye leaching out before the pores manage to seal over.

I suppose an easy solution would be to get some commercial sealer. This is what I use and I've never had a problem with dye leaching out during the sealing process.

If you want to save pennies then maybe try some other things. If you are currently adding the dyed parts to boiling water then there is no way to increase the heat (which is what causes the pores to seal) so what you would probably have to do is decrease the leaching effect - Steaming might work - usually this would take a little longer - about 30 mins to seal the pores over.

Past that I think you would need to look at the size of the pores - large pores might cause the dye to take well but also leach out well. This would be to do with your current density but from my calculations you have a current density of 4.3A/sqft which should be fine. There may however be something I am missing nere which a more experienced anodiser might be able to point out.

[Tim Wiltse]

jagrc,

When sealing with water don't drop it into the boiling water at first. Placing the part straight into boiling water will make most all of the dye leach out of the pores before it is sealed. Hang the part in the steam for 30 minutes or so first. I only place my parts in the water for 10 minutes or so at the end of the process. Not boiling but after I have turned off the burner. Try it, it will work.


Later,
Tim

[jagrc]

One thing I should mention, this is my second anodizing setup. My first setup was two aluminum cathodes about 2-3" off the bottom of my tank. The cathodes were about 3/4" in dia and about 6" long. My acid mix was 50% acid to water. With this setup I had great success getting color and it actually would not leach out. However getting consistant color from part to part was our major problem. Caswell suggested the changes that set us where we are now. Since then I have not been able to get a single peice to anodize.

[Tim Wiltse]

jag,

Well it sounds to me the part is being anodized since it is taking the dye but then the boiling water is leaching it back out. Just try the steam, you'll get it!

Later,
Tim

[jagrc]

I decided to go back to my old anodizing process. I discovered today the acid I was using in the old process was 36%. I thought it was the same as battery acid which seems to me is 19.7% I think the higher percent acid has a lot to do with my consitancy problems. Thank you for your help I will post my results.

[Fibergeek]

Jagrc,
I don't follow your reasoning; as Whistule pointed out, a part that dyes well but leaches badly when sealing is a sure sign of excessive pore size.

If you increase the acid concentration, you will make the pores even larger, unless you also increase the current density substantially. The dissolution rate (the anodize dissolving as it forms) wil also be very high with acid that strong.

It sounds to me, that you were not actually anodizing at 4.3 A/sq.ft. (120 mA for a 4 sq.in. part) but at a lower current density. How did you measure the current?

I know several people who use something like Tim's steam sealing method; he is right, it works fine.

[jagrc]

I used a DVOM (Digital Volt Ohm Meter) to measure the amperage. The reason I am thinking about going to the other system is because I was able to get results with it. With the current system I am not getting anything. In fact now for some reason I cannot get my parts to even dye. Which would lead me to believe that it is not anodizing before. I did discover with my old setup the acide I used was 36% which was diluted 1:1 so what I was anodizing with was nearly straight battery acid. I think this has a lot to do with my consitancy problems. I know the LCD system is a good one, I just cannot get it to work.

[Fibergeek]

OK, You've discovered that the acid mix you were using with your old setup was too strong. This could very well be the cause of the consistancy problems you were having.

Try your old method again and let us know.

[jagrc]

Sorry if I am being a pain here, I am just anxious to get stuff done. I have an RC buggy torn apart right now that need anodizing before I put it back together.

[Fibergeek]

No need to apologize.

When you dilute your acid, go for something similar to Caswell's standard dilution; 1:2 Battery acid to water. LCD dilution will be be too weak if you are using standard (10-12 a/sq.ft.) current density.

[jagrc]

Hey I switched back to my old setup and things are going great! I started playing with splash anodizing I thought I would post what I have done thus far...





Sorry about the poor quality of the pictures. They really don't do the colors any justice!

[Tim Wiltse]

Jagrc,

Nice work What did you use for your masking material? What is your methode for the splash? I have used the product from Caswell's myself but find that the edges lift sometimes.

Later,
Tim

[jagrc]

I used good ole elmers rubber cement. I put my part in the dye bath, pulled it out applied the cement (Just kinda let is ooz from the brush all over the part) let it setup bleached the part the moved on to the next die. then peeled the rubber cement off. The one thing I learned is smaller lines are a royal pain to get the rubber cement off, more is usually better in this case. I'll keep ya'll posted on my progress I am having great fun with this!

[Tim Wiltse]

Jag,


Good stuff! I had tried rubber cement at first to. The problem I had was peeling in off clean. It was like sticking to the part. I'm glad it works for you. How do you keep your part wet during the masking?

Later,
Tim