Question about coating rods

hiroh · Apr 10, 2023

I coat my paper with brushes and I like the process and the look. But I never tried coating rods, so I decided to at least give it a try. Maybe I'll like it, maybe I won't.

But before I purchase, I have a question regarding size. I've seen rods in the sizes of 7, 10, 11, etc... but these are the sizes of my papers — 5x7, 8x10, 11x14.... What I usually do with the brush, is that I leave around 1/2" border on each side of the paper, so if my paper is 11" wide, the print will be 10". And more or less everyone I've seen or know, does this way, leave the borders.

How am I able to do this with the rods, if the width is the same as the paper? Obviously, I can get larger paper, but that's not what I want to do.

koraks · Apr 10, 2023

Not sure if I understand what you mean, but there's no requirement that the rod is the same length as the paper. You can generally only coat a band that's slightly narrower than the length of the rod, otherwise you get trails of excess sensitizer on either side of the rod and that will flow back into the image area, creating coating unevenness problems. So a 10" rod will generally coat something like a 9" strip max. It takes a little practice/experience to optimize things.

It's also difficult to coat right up to the edge of the paper since you'll get sensitizer flowing underneath the paper. So it's a good idea to keep an uncoated margin along the edges of the paper, as you're doing.

For your papers, you could make do with only a 12" (or slightly longer) rod. This will allow you to coat all paper sizes you listed up to 11x14". Alternatively, you could get various rods if you prefer coating smaller papers with a smaller rod.

Personally, when I was doing a lot of rod coating, I fashioned a puddle pusher out of a length of PVC pipe (the stuff used for electrical insulation) with a scrap bit of laminate flooring glued to it. Believe it or not, but this worked great for stuff like salt prints, Van Dyke's, cyanotypes etc. I mostly used it for salt prints because most other processes coat just fine with a brush and I found no major advantages to rod coating.

What kind of chemistry are you planning to coat with your rods?

Kino · Apr 10, 2023

One of the best sites on coating paper with a puddle pusher is Denise Ross's "The Light Farm".

The Light Farm

Dig-around on her website and, perchance, order her book;

The Handmade Silver Gelatin Emulsion Print: Creating Your Own Liquid Emulsions for Black & White Paper

The Handmade Silver Gelatin Emulsion Print is a cookbook of simple, basic recipes for making black and white printing paper and paper negatives, along with creative options for printing, toning, and coloring. Author Denise Ross draws from photographic literature from the last 135 years, adapting...

www.routledge.com

It's a great book, full of very practical tips on coating with a puddle pusher.

nmp · Apr 10, 2023

koraks said:
I fashioned a puddle pusher out of a length of PVC pipe (the stuff used for electrical insulation) with a scrap bit of laminate flooring glued to it. Believe it or not, but this worked great for stuff like salt prints, Van Dyke's, cyanotypes etc.

Another diy option. After breaking my commercial, expensive coating rod, I bought a couple of these. They are nice and thick-walled and straight as can be. They come only in 12" size but I suppose you can get them cut.

Gauge Glass 1724006 - The Home Depot

Get the Gauge Glass 1724006, clear fitted to your boiler's gauge frame to allow the boiler water level to be seen from The Home Depot

www.homedepot.com

:Niranjan.

mug · Apr 10, 2023

Here in the Netherlands (or DE/BE /F) you can buy a glass straw, of heat-resistant glass. Those work very well.

Rietje, hittebestendig glas

Bekijk onze Rietje, hittebestendig glas van €1.25 en nog veel meer in Plasticvrij. Gratis verzonden vanaf € 39,- of kom langs in onze winkels!

www.dille-kamille.nl

Or
You can also buy glass stirrers made of Duran glass at a laboratory store
Or glass tube or glass rod at a glass art shop

Alan9940 · Apr 10, 2023

There's no rule that says you have to lay a bead of coating across the entire length of the rod. I often make 4x5 inch prints using a 6-inch glass rod. I fill a syringe with sensitizer, place a bead along the rod for the width I intend to coat, then draw across and back a few times. Just make sure you push in a relatively straight line and it will be fine.

MTGseattle · Apr 10, 2023

I happened upon some vintage Pyrex gauge tubes once upon a time. They're hollow, but they may still be worth a try?

L Gebhardt · Apr 10, 2023

nmp said:
Another diy option. After breaking my commercial, expensive coating rod, I bought a couple of these. They are nice and thick-walled and straight as can be. They come only in 12" size but I suppose you can get them cut.

Gauge Glass 1724006 - The Home Depot

Get the Gauge Glass 1724006, clear fitted to your boiler's gauge frame to allow the boiler water level to be seen from The Home Depot

www.homedepot.com

:Niranjan.

That’s a great idea. On the HD link a cutter is offered for sale as a related item.

nmp · Apr 11, 2023

L Gebhardt said:
That’s a great idea. On the HD link a cutter is offered for sale as a related item.

I figured you actually don't need to cut it to size. You don't even need to stick a handle on it. I use an elevated platform where I affix my paper and then use a hand on each end to do the passes - very much similar to what is shown in this great salt print instructional video using plastic tube, a la @koraks:

:Niranjan.

nmp · Apr 11, 2023

Come to think of it, a plastic rod might have an advantage over glass, particularly when the paper is smaller than the rod. Glass (clean) is hydrophilic enough that the sensitizer will wet all over the length of the rod so as you do passes the coating will not easily confined to the initial bead placement. Plastic is hydrophobic so it will resist this tendency and the bead will stay put. I am just guessing since I have personally not used a plastic rod but the video above is a nice demonstration of that.

:Niranjan.

hiroh · Apr 16, 2023

koraks said:
Not sure if I understand what you mean, but there's no requirement that the rod is the same length as the paper. You can generally only coat a band that's slightly narrower than the length of the rod, otherwise you get trails of excess sensitizer on either side of the rod and that will flow back into the image area, creating coating unevenness problems. So a 10" rod will generally coat something like a 9" strip max. It takes a little practice/experience to optimize things.

It's also difficult to coat right up to the edge of the paper since you'll get sensitizer flowing underneath the paper. So it's a good idea to keep an uncoated margin along the edges of the paper, as you're doing.

For your papers, you could make do with only a 12" (or slightly longer) rod. This will allow you to coat all paper sizes you listed up to 11x14". Alternatively, you could get various rods if you prefer coating smaller papers with a smaller rod.

Personally, when I was doing a lot of rod coating, I fashioned a puddle pusher out of a length of PVC pipe (the stuff used for electrical insulation) with a scrap bit of laminate flooring glued to it. Believe it or not, but this worked great for stuff like salt prints, Van Dyke's, cyanotypes etc. I mostly used it for salt prints because most other processes coat just fine with a brush and I found no major advantages to rod coating.

What kind of chemistry are you planning to coat with your rods?

Do you mean to cut the 12" rod to 10" and then use it on 11x14 (in my case 11x15") paper? I want to have 1/2" margin on all sides. So my prints are usually 10x14 on 11x15 paper. I'd either need 10" or 14" rod.

For coating, I use mix of Ferric Oxalate, pre-mixed solution of Pt/Pd an 1-2 drops of Tween.

hiroh · Apr 16, 2023

Actually, I just found that Bostick&Sullivan has 14" coating rods:

Coating Rod - Puddle Pusher

Glass Coating Rod 11×14

www.bostick-sullivan.com

Guess that's exactly what I need.

koraks · Apr 16, 2023

hiroh said:
Do you mean to cut the 12" rod to 10" and then use it on 11x14 (in my case 11x15") paper? I want to have 1/2" margin on all sides. So my prints are usually 10x14 on 11x15 paper. I'd either need 10" or 14" rod.

No, you don't have to coat to the full length of the rod. In fact, in my experience that doesn't work very well due to spillage. You can coat a 10"x13" area on 11"x14" paper with a 12" rod. Or a 15" one. Or even 20". It doesn't matter.

It does take practice to rod coat a nicely rectangular area with parallel sides, regardless of the length of the rod. There's technique to it, and the amount of liquid must match the area and absorbency of the paper quite well.

hiroh · Apr 16, 2023

koraks said:
No, you don't have to coat to the full length of the rod. In fact, in my experience that doesn't work very well due to spillage. You can coat a 10"x13" area on 11"x14" paper with a 12" rod. Or a 15" one. Or even 20". It doesn't matter.

It does take practice to rod coat a nicely rectangular area with parallel sides, regardless of the length of the rod. There's technique to it, and the amount of liquid must match the area and absorbency of the paper quite well.

Gotcha! I ordered 14" from B&S, so I'll try it as soon as it arrives.

Question about coating rods

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