Homebrew PCBs

Brad,

A couple of thoughts:

I have used Bar Keeper's Friend on some stubbornly oxidized boards. It 
contains some oxalic acid, so wear gloves.

When a board is completely clean, it will support a continuous film of 
water. If you hold the board horizontal, and pour enough water on it to 
cover it, the water spreads out, and will pull away from any place that 
is not clean.  Pat the board dry with clean paper towels.

Harvey A

On 7/6/2017 12:41 PM, allan.hale@... [Homebrew_PCBs] wrote:
>
> Hi Brad,
>
>
> On the severely oxidized portion of the boards you can try two items,  
> Straight, clear ammonia  NH4OH or sudsy ammonia with several 
> applications it should clean off the old board but may take several 
> applications tro achieve your desired results.
>
>
> One other item to try is "Tarn-X" available at Walgreens and CVS 
> stores.  This product is a thio-urea based cleaner and works wonders 
> on PC boards based on personal experience. I'd avoid the sandpaper or 
> emery cloth abrasive materials in favor of the liquid cleaner products.
>
>
> When you get the copper mostly clean you could use "Brasso" to bring 
> up a shine on the board, then wash with Dawn dishwashing detergent to 
> remove any remaining oils followed by a clean water rinse and dryoff, 
> before you proceed to the toner transfer process.  This practice 
> should get your board almost surgically clean which is what you need 
> for a really successful transfer process.
>
>
> Best of luck in your endeavors!
>
>
> Allan,   WA9IRS
>
>