Homebrew PCBs

I did a search on toner density spray, to see what it is. From several 
sites that I found, unsurprisingly, that it appears to be a combination 
of solvents like toluene and acetone. Further research brought me to 
this thread:

http://www.ar15.com/forums/t_10_22/675026_Enhancing_the_contrast__density__of_laser_generated__toner__PCB_transparency_artwork_w__acetone.html

After reading it, it reminds me of two other activities that have been 
discussed on this forum. The first is the "setting" of the toner on Mark 
Lerman's direct laser print to the board, where he suspends the board 
over acetone to let the fumes reflow the toner, and the second is the 
cold toner transfer process that was discussed a while back. This also 
used acetone with denatured alcohol.

The thread describes various way to reflow the toner, but in  the end, 
they are variations of getting a small amount of solvent onto the 
surface, and letting it reflow the toner before evaporating. This thread 
brings us full circle to our other activities, that show that acetone, 
and possibly, some other solvents have the capability to improve the 
toner coverage in several different approaches to making PCBs.

Other items of interest in the thread have to do with testing printers 
and scanners for resolution. Some nice, detailed instructions.

Harvey
On 2/2/2017 2:58 AM, Kamen Lilov kamenl@... [Homebrew_PCBs] wrote:
>
> Here is my setup:
> * LaserJet 2100 - bought this refurb for about $80, including refilled 
> cartridge
> * LaserJer has ethernet module (otherwise it's LPT only, difficult to 
> drive in this day and age)
> * Drafting paper
> * Set the density to 5 (default is 3, tried to do this via the new 
> Universal Printer driver and failed, then did it by sending the 
> specific escape codes via lpr to the network port where I have 
> attached it)
>
> I used to print two copies on the drafting paper and align and glue 
> them perfectly. Worked well. Then I read about and bought a toner 
> density spray. It's technically designed for transparencies, but works 
> very well with the drafting printouts too.
>
> I now only use only one copy. Blackness is perfect, going down to 12 
> mil traces every time and under than (e.g. for 0.65mm smd parts) with 
> some care.
>
> The critical part of my process now is getting a uniform thick coating 
> (I use Positiv 20 on bare stock). Exposure and black opacity is no 
> longer causing any troubles.
>
>