red dye

[jamerson]

can any one help? I cant get the red dye to take. could it be the dye or i dont have my settings right while im anodizing.

[sswee]

Need some more info. Is red the only color you are having problems with or the only color you have tried. What are your anodizing parameters. Electrolyte temp., SA of the part, cleaning procedures, CD desired, PS used, time anodized, is material type known? The forum can get you dialed in pretty quick if it has enough details. SS

[jamerson]

Ive tried green red orange and black. All of the colors take nicely except for the red. it seems like it gets half way there and stops. the electrolyte is between 64 and 70 degrees. I run it at 3 amps for 90 min. the parts are roughly 1.3 sq ft . First i remove the old ano, Then i degrease for 5 min. wash. then deoxidize for 5 min. wash. then 90 min anodize. wash. and nuetralize the parts in baking soda water. wash again. and then to the dye. Im not sure of grade of aluminum, but if it helps the parts are off of paintball guns.

[sswee]

According to the numbers you give, you are not anodizing long enough and at too low a current density(CD). I recommend using the 720 Rule for calculating your anodize times. It has been tested and known to give consistant results. There is a sticky on it that links to an Excel sheet you can copy, so all you have to do is put your numbers in.

I don't think you figured your CD correctly. Your part is 187.2 in sq (1.3 ft sq). If you want a CD of 3A/ft sq, divide 3A by 144 = .021A/in sq. Then .021 * 187.2 = 3.93A setting on the PS. 3A is the lowest CD for good dyeing properties.

The 720 rule states that you can grow a coating 1 mil (.001) thick in 720 amp minutes. The formula is 720 * ? mil / CD = Anodize minutes.
? = desired coating thickness (ranging from .5 to 1) It has been proven that any dye cannot penetrate more than .7mil deep. Best dyeing is normally around .5 to .7 mil.

For your part to dye good: 720 * .5 = 360 / 3 = 120 minutes anodizing.
You would have to go to a CD of 4.5A/ft sq to get an anodize time of 80 min.

Hope this helps and check out the sticky on the 720 rule calculator.
SS

[M_D]

Besides what sounds like a possible anodizing issue, you should check your red dye ph. If you do a search, you should find a thread or two about that. Off hand I don't remember, but I think the recommended ph is 5-6.

Red has some peculiar characteristics and may be the hardest color to deal with in some regards, for example sometimes the sealing changes the final shade. If the pores are too large you can have troubles with the seal making the color (any color) lighter because some dye gets washed out.

[jamerson]

Ok thanks ill give that a try. I will report tommorow.

[mcf74]

Re: red dye

yes I am having the same problem but I am trying to dye a casting. has anyone done this before with red? any success?

[sswee]

Re: red dye

Did everything seem ok while anodizing?
What did the red dye do?
Are you using a neutralizer dip tank?
Have you tried any other colors?
I have not had any trouble with the reds as long as the part had a good coating.

[acidrain]

Re: red dye

Jamerson, besides the CD being too low (try 4.5 to 6 amps per sq. ft), I noticed you're doing a wash between the strip, and de-ox. That step is unnecesary.
Also, I just discovered through some carefull experiments that a baking soda/water rinse to neutralize the acid bath inhibits a deep dye color. Try eliminating that as well, and just rinse well with distilled water.
Finally, you may be having problems with the cast material, but more likely it's your process giving you fits.