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  • SCD vs LCD

    Hi,

    Im new to the ano world and I saw a post comparing SCD to LCD anodizing with pictures. The SCD anodized part had better colour and less time in the ano bath. I will be getting a small business setup soon and would like to get the one that gives the best results.

    I was wondering if someone could define the difference between the two (spell out the acronyms aswell).

    I tried searching but didnt come up with anyting.

    Thanks

    JP

  • #2
    LCD means Low Current Density. This is defined as anodizing with an electrolyte about half as strong as "standard", and at current densities between 3 and 6 ASF.

    SCD means Standard Current Density, and uses stronger electrolyte 165g concentrated sulfuric acid per liter of water by weight (1 liter = 1000 grams). Current densities between about 9 and 20 ASF are used.

    The analog nature of the electrochemistry of anodizing permits thousands of permutations in the variables. So long as all of these variables are properly balanced good results can be had with nearly any formula. The trick is determining and maintaining the balance.

    Your statement that STD will produce better results than LCD isn't true, both can provide equal results. LCD takes proportionally more anodization time than SCD to obtain the same coating thickness.

    That said, then why LCD?
    LCD was optimized for use by beginners and casual hobby anodizers; it has some advantages for this, among them are:

    1. Chemically safer and much less noxious, you can do this safely in you basement or garage.
    2. Much smaller and cheaper power supplies. The power supply is the big buck item in anodizing.
    3. The fact that its slow; its much easier to maintain the correct anodizing temperature because the power dissipated is at a lower rate and spread over a longer time. The actual energy expended in SCD and LCD is the same for the same coating thickness. For most users a cooling system isn't required for LCD, its also much more tolerant of less than ideal agitation.
    4. Again the fact that its slow; beginners have an easier time recognizing that something is going wrong, and have time to react to it, before its done damage.

    Would you want to use LCD in a commercial operation? No, that's not what its for. We have many successful small (and not so small now) commercial anodizers here who started with LCD. When they learned and understood anodizing they were able to taylor a process that suited their own particular needs. I doubt if any two of them are exactly the same, this is a good thing. The quality of their anodizing and dyeing is consistently equal to or better than anything coming out of a traditional shop.

    You would be best served to start with LCD, it will take you less time to get to your desired process than thrashing around with SCD when you don't yet know what you are doing.

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