The Pnp blues

[MikeH]

I've had trouble with the last 2 boards I've done transfers on, with the pnp moving and giving me a "smeary" transfer.  Luckily, I've been able to clean up the transfer afterward by picking away the toner between traces that shouldn't be touching, and cleaning up traces with a sharpie, but what a pain.  The Tonpad photoessay doesn't say anything about affixing the pnp sheet in place, but should I be taping it or something?  Or will that muck it up worse?

[$uperpuma]

its VERY important that your iron isn't "dragging" on the PNP when you apply pressure...causing the PNP to drift.... I use both hands to apply pressure evenly straight down on the PNP until it is fairly affixed to the copper, then I iron down the traces

[Barcode80]

i too ruined a large chunk of pnp last night trying to etch two boards, with the same ironing problems. not only did i have smears, but with my iron on the maximum setting and after ironing for about 4-5 minutes, the traces barely even showed on the board.

[MikeH]

I haven't had any problems with getting it to transfer, it just keeps coming out smudgy.  I guess I need to work on my technique.

[mydementia]

For what it's worth - I put the iron on 'Wool' and set it on the PNP for 30 seconds - lift and rotate the iron 90 degrees - set for another 30 seconds.  I do this for two 'circles'.  I NEVER move the iron around because it just smears my traces.  This process takes about 4 minutes per board.  I quench in cold water, lift a little to be sure it worked and repeat the process if it didn't.  I've had VERY good luck with this process...

Good luck.
Mike

[MikeH]

Is it possible to overheat pnp, or iron it for too long?

[Mark Hammer]

Temperature and heat distribution will forever be an issue with PnP.  Fundamentally, the problem is "How will I know when it's done?", so what people are looking for is something equivalent to "Bake until brown on top".

The thing to remember about PnP is that the toner layer - assuming is is reasonably thick enough - is fairly thick, relative to the acetate backing sheet and blue emulsion.  And that provides our clues.

Imagine, if you will, that you have spelled out your name in Lego (one brick high), and laid a sheet of 1/4" masonite on top of it.  Okay, now imagine you had the power to heat masonite so that it become soft and droopy.  Now, what would the surface look like over top of those bricks you had laid out in a pattern to spell your name?  You would be able to make out a sort of "relief" pattern of what lay under the masonite.  Of course, it TOO much heat had been applied, you would melt the Lego bricks underneath, so not much would be visible.

And therein lies the "magic" of PnP ransfer.  You are essentially trying to warm up the acetate sheet enough that the toner fuses to the copper and the acetate gets droopy.  When you can make out the entire pattern in low relief, you're done.  It is an excellent indicator of the state of the toner underneath.  If you see any areas where, when you hold it up to the light, it still looks flat and shiny, then you need to go over those areas again, perhaps with the pointy end of the iron.

Just be VERY very sure that:
a) you haven't ironed so much that the toner underneath goes splat
b) the board is shiny clean and residue free so things stick to it
c) you let the board cool off completely before peeling off the backing (with winter coming on in so many places north of the equator, I recommend simply placing the hot board against a window-pane for quick thorough cleaning)

[Barcode80]

cool, judging from these replies my technique is severely lacking. i was moving the iron around, plus i was checking the transfer while still very hot. i will try again using all your suggestions and post results....

[Pushtone]

the pnp moving and giving me a "smeary" transfer.

Iron is too hot.

I use the POLYESTER setting with excellent results.
Toner is plastic. Polyester is plastic. Works.

I alternate between letting the iron sit for 20 sec
and rubbing with the nose of the iron.
I try and run over each trace like a burnisher.

[$uperpuma]

I alternate between letting the iron sit for 20 sec
and rubbing with the nose of the iron.
I try and run over each trace like a burnisher.

x2
the traces around the outside of the PnP seem to need extra care

[zjokka]

guys,

I've done some 10 boards or so, with photo paper/picture paper, using the iron on the linen (hottest) and never have never seen a smear. I bought pnp, even copied layout on them, but haven't used them yet. Every time I do a new board I yet more radical to find how it can go better. So lately I resorted to this ancient iron which I put on the gas burner until it's as hot as possible and just press it on the board and paper. Leave it on the board for 4 min or so. The reheat and carefully to the sides, but not so critical because this iron doesn't have hole in the bottom like modern ones. works perfectly for me. Have even reheated a couple of times.



Disavantage of picture paper is you don't see the traces so don't know when it's done, but if your surface and iron are flat it should be ok

there are advantages to pnp i believe, but the heat sensitivity seem to be a negative