here's a little tip,mist the board with water ensure the board is fully misted,squeegee all the air bubbles out,the water helps keep a vacuum and causes the film to vacuum suck onto the board,then either iron on or use the laminator. Applying the resist sheet to a dry board just traps air,it's the same thing with dryslide decals the water helps get the air out. Just make sure to squeegee out ALL of the water,you may need to run through the laminator twice or thrice,with the hot iron a sheet or two of kitchen roll to help make full thermal contact and press the film fully onto the board as the board is not perfectly flat. The UV exposure is by far the best method for pcb manufacture,with screen printing a close tie,both use UV exposure for the image,i've tried both ,the silk screen for is more expensive with the negative resist from china being the favoured method for cost effectiveness and less wastefull. You can buy liquid resist thinned with acetone,i have some and i'm bursting to try it out ,it drys in a few hours,i could apply it with a hard rubber roller like lithographic stamps. I have a few sheets of presensitised copper sheet,a 5m roll of the neg resist and the wet resist,for two pcbs no bigger than a square inch or so each,one is a smps booster for tube HT and the other is a buffer op amp for the tubes output,small daughter boards for breadboarding the tubes. I have caustic soda,i had to order the soda crystals for two reasons,one i can't find the caustic soad!!!!!! and second i remember the caustic soda removing the resist layer completely from the board it being a little too aggressive ,big clive (a fellow scot) used the soda crystals and in no time the job was done and in a far less aggressive manner. I'll share another tip i gave to big clive,and another Scottish tip too,the etchant ferric chloride is great in a bubbler tank also in a passive tub,i made tube amps with brass facia plates with the decals etched into the brass,it took ages to cut the brass with it being a copper zinc alloy a lot of smut was building up and frequent use of a babies tooth brush to clear said smut. I found out that a fluid for etching brass and it works amazing on copper,it clears the smut in a passive tank and reduces etch time in an active (bubble) tank,it is called EDINBURGH ETCHANT. Edinburgh etchant is ferric chloride mixed with citric acid,i bought citric acid powder from ebay few table spoons in the tank you have there would be fine,the effect is amazing with regards to how clean and quickly the pcb or brass is etched and the brass particularly noticeably deep and crisp edges,without under cutting as was the case before due to the time taken,the citric acid kept it clear of smut,that's what the pcb bubbles are for,time is reduced considerably to make a pcb,very uniform fast etch,be careful.

for sharpest possible image transfer you do want to flip the F side, since dye or toner is printed on one side of transparency and it should be closest to pcb or some light will refract and spill into transparency and under it

If you put the transparency in the thin box together with a cotton ball, paper tissue or something similar soaked in acetone for a couple of minutes, you will get much more contrasty print, and won't need to use two transparencies. I had a printing company long ago, and we were printing tons of user manuals for appliances, TV sets and such. We used laser printed tracing paper, and it worked perfectly, no reason why it wouldn't work with transparencies.

Thanks Ian. I use the same process, always nice to see what "tricks" others use. I've never done double sided so your pocket method has given me some confidence. Getting that first film layer off is a pain, I use two bits of tape, one on each side and in the same corner - works a treat. An option for others to get the negative ... in my case print the positive on to paper (I have an ink jet), then take the page to a copier centre ... they can copy on to laminate and those commercial copiers have a setting to print "negative".

I am not sure if it really worked for me, but I used to completely submerge the board and the resist under water. Then get the resist and board aligned on the top edge. When you lift it out of the water, top edge first, surface tension will pull the resist to the board without any bubbles or wrinkles. As I remember it, there was no "free" water under the film but I assumed the film absorbed some so I let them dry in a warm dark place for a while. BUT I did run into problems which may or may not have had anything to do with the water bath. Often the resist was very resistant to coming off where it should. It is more likely my UV light wasn't diffuse enough, or I was overexposing. I think the film was also getting old and slightly exposed looking off the roll. The other problem, I think might be fixed by doubling up the transparency like you did but for some reason it didn't occur to me to try that. I ended up with lots of little pinholes in the resist and copper. On the other hand, it could have been mini steam bubbles from the water bath and laminater. After etching, I think I removed the resist with acetone rather than lye. Assuming I'm not full of crap, I think that might be a little safer to work with, especially if done outside. Seems like the body even makes a little acetone as part of normal metabolism so it might be equipped to deal with a whiff of fumes every now and then. Anyway, yours turned out a lot better looking then mine but I thought you might want to see if the water bather helps or hurts your process.

In Printer Options turn on Enhance Black Printing and you should get really Black Blacks.

You should maybe replace the metal tabs in the picture frame come tool every six to twelve months as the tabs are prone to getting brittle and break.

Nice video Ian, few tips : 1. Use a small sprayer (like perfume sprayer) filled with distilled water and apply a thin mist of water on (little more cleaned PCB clad- with scotch brite and dishwasher and IPA later) the PCB and then gentle put the UV Resist and use a Squeeze or old credit card to remove any bubble, also removing all the water. let it dry a bit and then put it in hot roller to finally seal it. this will give you mirror finish without any bubble. 2. After developing the exposed PCB un Sodium carbonate, quickly dry the board (in my polluted country, the polluted air attacks the copper in no time) and place a clear OHP sheet on both sides and expose under UV for another 4-5 minutes. this will make the UV mask rock solid. - VU3ECN

Just make sure that Transparency Film won't melt at the fusing temperature that fusing rollers operates at.

Very interesting video ! Wondering do you need a professional PCB supplier to help you get your project done ?

I have a tool that I bought from the UK at great expense that looks like a gigantic stapler which you can load little tiny hollow copper pins into. When you engage the device it forces the hollow copper pins into the drilled pcb hole and creates a via that attaches the upper and lower copper surface of the board. You can buy the pins with different via sizes. The pins in 1000 quantity aren't cheap either. The tragedy is I've had the device for years but I've never used it.

The Photorest Method is tried and tested.

It's also worth playing with using a resin style 3D printer which have UV screens so you can expose directly onto the UV resist PCB. I use an Elegoo Mars 4k and it gives very satisfactory results.

I'm wondering why you switched from your previous method? Perhaps you mentioned why but if so I missed it