Sizing paper for coating

[M Carter]

Been searching the threads, I've found PE's coating formula (gelatin & glyoxal).

Couple questions though (for starters, this is for coating with liquid emulsion, not carbon or cyanotype and so on - yeah, I'm a lightweight, just using Fomaspeed). I've read everything I can find online about sizing. PE's post included coating the paper using "any of the common methods such as brush, dip, coating blade etc...". Seems like paper in the tray of warm gelatin+hardener for 3-5 minutes, remove it by dragging the paper over the edge of the tray is a good way to go.

I've seen posts that mention a next step of setting the paper on glass and squeegieing the coating off with a glass rod or rubber squeegie to push it into the paper and get a drip-free sheet when hung to dry. And also articles stating that even with this gelatine+hardener in the same process (vs. gelatin followed by hardener) that the paper needs a rinse in cold water to set the gelatin. So I'm assuming this step doesn't rinse a lot of sizing from the paper?

Any info on which steps to follow? I'll be using hot press paper that's very smooth, trying to get a surface much like the back of a commercial fiber paper.

 

[dwross]

Many papers don't need extra sizing, and some get hard to process if additional sizing is added. Arches Aquarelle is one of these. It's already gelatin-sized. This is a step for thin papers. The gelatin sizing can change what feels like single-weight paper to a perceived double-weight. Rives BKF lightweight (115 gsm) is a good candidate.

Hardened gelatin sizing coats excellently with the wet paper technique -- the same technique you'll want to use after you size the paper. My formula is 5% photo gelatin with 5 drops glyoxal/100 ml water and 5 drops Photo-Flo/100 ml water. In other words, if you make a 5% gelatin solution with 10 g of gelatin and 200 ml water, add 10 drops of glyoxal and 10 drops of Photo-Flo. Coat at 40C on wet paper, squeegeed flat on a glass coating surface, with a puddle pusher prepped for wet coating. Let the coating set and then hang it to dry. To coat with emulsion, re-wet the paper for wet-paper coating.

 

[jim10219]

Always try it without sizing first. Even if you're sure you're going to need to size the paper, it helps to get a baseline to know how much. After you've figured out how much size you need, then work on the best way to apply it. Some methods are great for heavily sizing paper and some methods are better for lightly sizing paper. The paper, the size, the emulsion, the tools you have available... it'll all play an effect on what works best for you.

Your best bet is to keep it simple, and not add any unnecessary steps. You'll be better off if you try to limit yourself to addressing actual problems that you've experienced, rather than trying to address problems that you may theoretically experience with stuff like this. For most of the papers I've worked with, sizing is only necessary when doing multiple exposures and washes.

 

[M Carter]

Always try it without sizing first. Even if you're sure you're going to need to size the paper, it helps to get a baseline to know how much. After you've figured out how much size you need, then work on the best way to apply it. Some methods are great for heavily sizing paper and some methods are better for lightly sizing paper. The paper, the size, the emulsion, the tools you have available... it'll all play an effect on what works best for you.

Your best bet is to keep it simple, and not add any unnecessary steps. You'll be better off if you try to limit yourself to addressing actual problems that you've experienced, rather than trying to address problems that you may theoretically experience with stuff like this. For most of the papers I've worked with, sizing is only necessary when doing multiple exposures and washes.

Nope, it's not theory - I've tried 2 hot-press papers and the paper texture is too big a part of the final image for this project. I'm getting the best results from fixing out fiber paper and coating the back, but that gives me some drying issues with the sticky emulsion on the now-back, it can slide around when coating, and it adds the extra steps of fixing and washing. And emulsion on both sides seems to really extend the drying time. And this is for Bromoil, so I already have the wet coating, processing, washing, tanning, fixing, washing, and soaking steps, though the emulsion is holding up well on unsized paper. It's the texture that's bugging me, but baryta paper is awfully pricey at the size I need (16x20 now but I could really use 20x24 for this project). I could certainly see projects where some texture is a plus, just not for this.

I'm wet coating the emulsion on room-temperature glass; I chill a damp towel in the freezer for ten minutes and put it in a soft cooler while the emulsion is melting. After I coat the emulsion, I set the glass on the cold towel and the emulsion gels pretty quickly and I can peel away the excess and hang it up. I'm getting a really close-to-factory smoothness that way, done some 11x14 and doing 16x20 next. I just need to find a solution that mimics a nice factory fiber matte paper - the foma emulsion really kicks ass for bromoil, like nothing I've ever used - in fact it's like a "new kind of bromoil" as far as ease of inking - even beats the old Agfa MCC matte.

Anyway, I'm waiting on a gelatin and glyoxal order and I'll give your formula a try - and to clarify, this doesn't require a cold water rinse after coating? So much conflicting info out there! Thanks loads.

 

[dwross]

No cold water rinse. It's just two coating layers on the same side of the paper. Wet coating makes it so that each subsequent layer is coated on dead-flat paper. Essential for even, smooth coatings with multiple coatings. Looking forward to seeing your results.

 

[grainyvision]

Many papers don't need extra sizing, and some get hard to process if additional sizing is added. Arches Aquarelle is one of these. It's already gelatin-sized. This is a step for thin papers. The gelatin sizing can change what feels like single-weight paper to a perceived double-weight. Rives BKF lightweight (115 gsm) is a good candidate.

Hardened gelatin sizing coats excellently with the wet paper technique -- the same technique you'll want to use after you size the paper. My formula is 5% photo gelatin with 5 drops glyoxal/100 ml water and 5 drops Photo-Flo/100 ml water. In other words, if you make a 5% gelatin solution with 10 g of gelatin and 200 ml water, add 10 drops of glyoxal and 10 drops of Photo-Flo. Coat at 40C on wet paper, squeegeed flat on a glass coating surface, with a puddle pusher prepped for wet coating. Let the coating set and then hang it to dry. To coat with emulsion, re-wet the paper for wet-paper coating.

A bit off topic here, but I've found that Arches Aquarelle (the block one with the pink cover) did not work at all for me with wet emulsion coating (didn't try pre-sizing). I mean, it works but the coating tended to be uneven and more importantly would seep into the paper, giving black spots etc on the back of the print and in general a rather powdery feel. In other non-emulsion processes like salt printing, the paper would bubble when dipping into a citric acid solution and the silver nitrate solution would also seep into the back in that case as well, even with a conservative 2% gelatin salted sizing applied. Do you happen to know if this paper has changed or something? My batch was ordered I think around the time of this post likely based on your recommendation somewhere as it being a safe paper, but that seems to distinctly not be the case in my experience. Absolute best paper I've tried thus far is whatever Photographer's Formulary sells as platinum rag paper. Expensive, but always works perfectly. My only complaint is it's a little thin and the surface can be a bit too smooth if that makes sense.

 

[Vaughn]

How about albumin (egg whites) as a coating? Glossy, hardened with spritz of alcohol.