Question re dyes

[spudnik]

Hi Guys
I have just set up a small run and it seems to be working ok but i have been trying to use dylon fabric dyes just to see how they go before getting some proper dyes from here.
The part is becoming non conductive as it should but it does not accept any color at all.
I am useing a 12volt 30amp charger to power it and it is running at 14ish Volts and starts of at about 10 amps and then drops down to around 4-5amps, i am only doing very small parts.
Will it just be the dyes that are not working or is there something wrong with teh way i am anodizing it.

any help would be greatly appriciated

[dmiom]

Firstly, you're on the right track by getting proper anodising dyes - fabric dyes are notorious for giving poor / no colour in this environment.

Secondly, your power supply needs improving if you wish to produce reliable, consistent anodising. If you want the honey-comb matrix to be grown in regular size which will evenly accept dye, you need a constant-current setup. You can do this by modifying your charger circuit and manually adjusting it for the couple of hours necessary; but if you're doing this more than very occaisionally, you will need a constant-current power supply - have a look at the Why do I need a Constant Current power supply sticky at the head of this forum.

Other factors which might be having an impact are surface prep / degreasing to water-break test, correct make up of the chemical tanks (strength) and running them at the correct temperature; using distilled or RO/DI water for absolutely everything (tanks and rinsing); cross-contamination of tanks by carry-over after inadequate RO/DI rinsing between processes; racking; surface area measurement & current calculation; timing variation .... If you haven't done so already, you'll find it useful to read the LCD Anodising instructions which Caswell have kindly placed online. The Caswell LCD method isn't the only method of type II anodising - but it is an easy one which has been developed to take some of the difficult parameters out of the equation and produce repeatable results with a little care,

It may sound daunting - but if you follow the LCD method it can give excellent, consistent results - its not hard, just needs care. You can also (as we have done) use it as a foundation from which to scale up to a larger line.

and of course have a read through the posts on here - between us we've encountered most issues over the years, so if you're following the LCD method and then have problems, search the board and then ask away - above all take care & have fun!

Dave

[spankey666]

as he said

[spudnik]

Hi guys
Thanks for the quick replys!!

It looks like it is working as i now have a colored part in my hands.

Will definatly be getting some proper dyes but i am surprised how rich the color is with the dylon dyes.

Thanks again for your help, looks like i have some reading ahead

Cheers

[stayhi]

sure it works, just dont expect consistent results or to trouble shoot if you have a problem because the power supply just leaves too many unknown variables.

[spankey666]

my first experience with Dylon dyes was with scarlet red. came out stunning, so tried black, bad- no colour absorbsion. spent ages dickin around with my setup (battery charger supply ) before buying some black from caswell. instant good results. dylon black doesnt work !!! as ive said before in previous posts, good results are achievable with just a battery charger, but the results can be unpredictable, and if you want help its hard to give if you havent followed the 720 rule that everyone on here uses.

[spudnik]

this is the power supply i have
Centaur Charger 12 / 24 Volt - Victron Energy
its teh 12v 30amp one
It seems to work well so far anyway
is this the type i should have?

[dmiom]

Originally Posted by spudnik

this is the power supply i have
Centaur Charger 12 / 24 Volt - Victron Energy
its teh 12v 30amp one
It seems to work well so far anyway
is this the type i should have?

That's a battery charger, and a relatively sophisticated one at that, not a constant-current supply - so regret that the answer is no.

A battery charger is typically of two types - either a constant voltage or one which follows a profile - neither of which is really suitable for LCD anodising, which needs a constant current (some plating technologies need a constant voltage, which a basic charger can supply - but that's not the case for LCD anodising unfortunately).

The simplest chargers are a constant voltage unit which, for say a 12v battery, have an output of maybe 14.5v. The only effective regulation is that as the battery is charged and its cell potential reaches that of the charger, the current diminishes due to the back EMF from the cells. The only variety therein is that "Trickle" chargers apply less voltage than "Boost" chargers.

An "intelligent" charger varies the voltage to match the optimum charging profile of the battery, so if the cell is depleted, they'll start off with a lower voltage to avoid over-heating or over-gassing the battery and then as the battery gets charged more, keep increasing the voltage so it keeps, maybe, one or two volts above the battery; then as the battery gets near full voltage, they throttle-back the charging voltage to avoid un-necessary gassing; and then when the battery reaches its fully-charged potential, the charger can drop its voltage and revert to a maintenance/trickle charging mode. This is even more the case for chargers for modern battery technologies (Li-ion, LiPol etc.) as they have sophisticated, fixed charging profiles, knee-detection etc.; and even worse, some intelligent battery chargers discharge the battery before charging it. True, occaisionanally you can still come across constant-current chargers to trickle-charge older NiCad batteries - but they typically only output only a few, or tens, of milliamps - maybe enough to anodise a paper-clip - and then only of one particular size!

All of this means that you don't have any chance of anodising at a predictable constant current which is what you need to ensure the honeycomb cells grow in a regular, uniform, predictable matrix.

You need find a power supply supply which has an adjustable, constant current output.

A constant current supply is one which allows you to set the current (which depending on your workpiece size could be 0.8 A or or 10A or 30.8 A or ....) and the power supply then varies the voltage to ensure it pushes that current through the load (the anodising tank/cell).

The first thing you do is measure the surface area of the work to be anodised, and then multiply it by the chosen current density, typically 4.5 - 6 ASF (Amps per Square Foot) for Caswell LCD to get the required constant current. You then set this this as the required constant current on your supply. If not enough current is flowing, the power supply raises the output voltage until the commanded current is achieved. As the anodising layer builds up, the effective resistance of the tank varies, and the power supply will modulate the voltage to keep a constant current.

When selecting a constant current capable supply, you want to look for one:

• which has a constant current mode
• which allows to you to set the current (ideally to perhaps 0.1 A resolution)
• which can supply sufficient current (using LCD method you need 6 ASF so take the largest area you want to anodise at any one time in your tank and multiply by 6, and then maybe add a little margin for racking etc.)
• which has sufficient voltage headroom (you don't set the voltage, but you do need enough capacity to allow the power supply to push the commanded current - so would suggest a unit with at least, say 20v capacity)

Exactly as the others guys have said above - if you just want to try experimenting, yes, use a charger (preferrably a very dumb, simple one) but don't expect reliable results and I'm afraid you won't get help. Many have tried and then migrate to a suitable constant-current-capable supply.

Dave

[spudnik]

Hi Dave
Thanks for that
so something like this would be better then?

Manson Engineering Industrial Ltd.*|*Products*|*Product Detail

[BobFrapples]

That looks like a good rectifier, SPS-9602 1-30V, 30A
The other 1-15V 60A, has too low voltage and won't be too applicable.