Personally, I use a photographic process, I find that it yields repeatable work, especially for higher resolution/greater density or smt/mixed boards.
I used to coat my own boards on a large scale, then live off the stock for 6 months at a time, but now it's as cheap to just buy in pre-sensitised stock whenever I need it.
I know a lot of folks have hit and miss results with it though, but I find that generally it is because they often unknowingly alter their process each time.
Build yourself a proper exposure frame with a decent lamp that you can semi-permanently fix the height of and build in an accurate timer to control the lamp. Run a test strip for each new batch of board stock so you know exactly what the correct exposure time should be, what height the lamp should be to properly expose the whole board without shadow and what strength of chemicals are required. The major advantage of using a frame, is that you can get registration perfect if you are making double sided boards, something the Toner/contact method is very tricky to do with.
For the developing chemicals, mostly any caustic soda solution will do, you can get it from some hardware places or pharmacies, often it is sold as drain cleaner. Board stockists can give you non caustic stuff as well, but it's a little more costly. Use measuring spatulas and marked jugs for your make up water so you can repeat the solution strength with some degree of accuracy, remember you are aiming for consistent repeatable results. All you then need do each time you make a board is set your exposure timer, lamp height and chemical strength accordingly. I have heard all sorts of stuff like use distilled water etc over the years, but unless you are planning on keeping the chemicals in made up form for months at a time, it's better to just make up what you need. I usually use Malted Vinegar to neutralise the spent developer, and as a fixer for the developed board prior to etching. I also have a tray that I put cool clean water in to store the board between processes, I find that by keeping the board away from the air as much as possible there's much less chance of oxide build up causing dead spots in the etching process, and is especially required if I go on to tin plate the board, as is often the case with my boards.
Use cool water when developing the board, keep it at or below 15 degrees and the development process will be slow enough that you can watch things and correct them if the board is over exposed, or your development solution is too strong. After a bit of experience, you'll instinctively know how warm the solution needs to be just by holding your development tray in your hands. Usually a quick wash of the partially developed board in cold water is enough to stop the resist washing away before your eyes. Just remember that the warmer and stronger the solution is, the faster the development, to the point where it will wash your entire artwork away. Direct sunlight is to be avoided when handling the exposed board, but a dull overcast day generally allows me enough time to handle it during processing, on bright days, I usually just close the blinds over a bit. I used to use an ordinary yellow coloured incandescent lamp as a safe light because the films and board stock used to be really sensitive to daylight, but nowadays, the stuff can pretty much be handled in daylight for short periods without negative effects.
If you make sure your process is fairly stable and repeatable each time, you should have fantastic quality boards each time, but alas that's not always the case. Small variations in board stock mid batch etc can affect the development stage, but if you go slow with it, you can always stop the development by rinsing the board in cold water and add a smidge more caustic to your make up or warm it up a little to help an under exposed board clear, or dilute your already too strong solution to help an over exposed board.
I have also tried the Toner/contact method using various papers and had moderately good results with it, but I found that it's is strewn with the same pitfalls the photo process has, i.e lack of experience and confidence and lends itself to the self same process altering characteristics the photo process has for loads of folks, unfortunately it's the downside of being human, only with a differrent set of process steps.
Also the board processing is sloppy using an iron because of varying contact pressure, even heating, removal of air bubbles, oxides etc etc, there is not really any way I can see that you can manually make that both accurate and repeatable, there will always be differences. It's a matter of whether you can control those sufficiently to produce repeatable results. I personally couldn't and scrapped as many boards as I was happy with.
Obviously one off boards are an exception here, as either process usually yields a workable board eventually. The one thing that the Toner/contact method has to it's advantage, is that bare copper clad board stock is used, so it''s a little cheaper and you get to see where your artwork let you down before ruining the board in etchant, you can always scrub it and try again etc till you get it right. With the photographic process you would do the same thing, but to the contact artwork, and not the board, giving rise to running a dozen perfect boards from the same artwork. The photo process also has the advantage that unless you are coating your own board stock, you don't need to clean it of oxides etc before use, it is a pretty much repeatable process.
For one off boards, either method will give you a result if your careful, for high density or smt boards, or boards where you need to run a couple of dozen off, the photo process will lend itself better in my opinion. It's all an art form and takes a little time to master. Either way you produce your boards, if you are like me, you will stand back and think it's a thing of beauty every time onee turns out the way you want.
Look at it this way, it's like cutting glass, if you have no experience and little confidence whilst doing it, you'll end up with a gazillion broken bits, but show a little confidence and use a sharp cutter each time, and you'll have perfectly cut glass.
Ok that was a rant, I admit it, and I'm somewhat biased here too.
I have used the photographic process for 20+ years, and really only used the Toner/contact method for 20 mins, well, ok, I used it for about a week, but obviously not long enough to build that glass cutting confidence that others have mastered.
), that leaves the regular gloss and the recycled news-print pages.
I still want to try the magazine paper. It makes since. But the lexmark photo paper and other papers at 100 sheets for $12.99.. They work, you just have to learm to let them soak long enough before you peel the paper off.
