why flat finish

[fragglerock]

I dyed my first test piece but the color came out flat, after anodizing are you supposed to repolish the part to get polished color look? It had a powdery surface that rubbed off easily but still had color underneath. My dye was at room temp and dyed the piece fine. I then sealed in CASWELL sealer that was boiling.The color was CASWELL fast blue. The finish was flat but had good color that rubbed off easy but still had color underneath. The piece was scrap diamond plate (12"x6"x1/4") that was anodized at 6amps for 120 minutes at 14 volts. Can you repolish after anodizing before dying?

[M_D]

You are probably seeing the effects of dissolution. Do a search on that word, there has been a lot of information and discussion posted on the subject that will be educational and help you to understand it, and hopefully learn what went wrong.

You can not polish anodized parts and dye them with success, once dissolution occurs the only remedy is to strip the part and try again. Of course, if you don't correct what went wrong in the first place, the problem will likely repeat.

[yoyoboy]

probly dissoultion, make sure you polish it to a nice shiny finish before you anodize it. Rember: Garbage in, garbage out.

[archimedes]

greetings Fragglerock,
If I may, can we take a couple steps back ---
to reconsider:

My dye was at room temp and dyed the piece fine.
Does this particular color of blue have instructions different from Caswell's
other colors they sell? Because the dye should not be at room temp.
You should have it set b/t 130-140dg F.

I then sealed in CASWELL sealer that was boiling.
Again, following a Caswell product instruction set-- this should not be
at boiling temp but instead at 90dg F.

that was anodized at 6amps for 120 minutes at 14 volts.
I am very curious here-- You wrote "6 amps", but did you actually set your
CC at 3 amps as the 720 rule calculated? Following in line with the dissolution
suggestions proposed would point to an actual CC of 6 and not 3. But this
of course begs the next question; What size is your CC power supply? If
its the 3 amp model, ummmmmm. But if you own the 20amp model . . . .

Finally, I will add most diamond plate is of the polished kind from the manufacturer. But this is a very inferior Aluminum alloy when compared to
the traditional "aircraft" grades (6061-t6, 7075-t6, 2024-t3). You may find
a barrel of experimentation to bring this substrate to the likes of the 3
higher quality grades mentioned above.
Also I would not mix your diamond plate with any other grades.

archi

[sswee]

archi,
Caswell offers two sealers for anodize. The standard nickle acetate is used at boil. The sealer LT is a reduced temp sealer that is not recommended for use with all colors of dye.

A part of 148.5" SA at a 6 ASF CD has a amperage setting of 6.19A. Run 120 minutes for a 1 mil coating with a projected peak voltage of 15V. The numbers jive for the run. The description given sounds like typical dissolution.

I didn't see anything on tank temp, agitation and acid concentration all of which can contribute highly to dissolution. The material grade can have a slight effect on it but is usually only a minor factor.

fragglerock,
Have you tried anything else or come to any conclusions?

SS

[archimedes]

thanks Sswee, for the catch.
yes--- the amp calculation is very close to the 6 amps stated.
Funny, after reviewing the dimensions I realized it mimics
Caswell's own rule of thumb:
for 1amp = 50sq" = 1 mil = 240'
1amp = 25sq" = 1 mil = 120' this is for a 6amp sq/ft base

Also to consider Fragglerock's results some more:
Given the diamond plate's material makeup I wonder if
he should hold the 6amp base and drop the anodizing time
25% (Mike C.'s comments in the "sticky" post).
Actually, I would drop the anodizing time by 1/2 and
review the results.

Sswee-- I have seen your putters done in the "fast blue".
Is that dye not brought to 130-140dg before use?

archi

[sswee]

I run all my dye tanks at 140 degrees. Why do you ask? Does the color look off to you? The putters are half polished and half glass beaded.

SS

[archimedes]

Sswee,

I run all my dye tanks at 140 degrees. Why do you ask?
It was part of Fragglerock's statement; ". . . the dye was at room temp." and
described the dye as "fast blue". I was curious about the temp. control of this dye. I was reviewing his operating parms and
this was one I thought was not in line with Caswell instructions. I have not used this dye myself.

The putters are half polished and half glass beaded.
Actually I did take a good look at your coloring and I liked the results!
The blue is very attractive--- I too have purchased some glass beads to
experiment with coloring results. I bought #12 size which is the finest grade
this particular company sold.
What size glass beads are you using?

archi

[sswee]

archi,
I wondered if you used the same color and was getting a totally different look or shade. I have all the colors Caswell offers and run them at 140 degrees. I have heard of several people using the dyes at room temp. and Caswell tell them that they can't offer support for dye problems if they don't use the products according to manufacturers recommendations. Understandable I think.

Honestly I didn't check the last bag for size when I dumped it in the blaster. I buy mine from a large fab company that makes ship portals and hatches. A couple of things to watch with glass bead. If you blast with too much pressure, the surface texture will be rough enough that the part will have a alum. gray tint or shade through the dye color. The fix I use for this if it happens is to strip and etch. Then re anodize and it will give a nice even color. The other common problem is people don't go over the part enough to make sure the surface finish is truly even. After blasting the part will visually look good but after anodize you will be able to see where the focus of the blast went and the rest was not hit as hard. Kind of like scribbling with the blaster gun. I usually use 50 to 70 psi and always at a 45 degree angle. I've used glass bead primarily for years and prefer it to most other media I've tried.

SS

[M_D]

From my experience, room temperature dye will not cause any imediate failures to the appearance. Heating the dye is best, but other than taking a bit longer to dye in some cases, and perhaps not holding the color as long in sunlight, etc., I haven't seen any obvious defects because of cold dye.