Pola Type 55 negative question

I may (finally!) be coming into a 4x5 camera and able to use the Polaroid 500 holder I've had for a couple years, possibly including using Type 55.

However, having recently shot a bunch of Type 667, I've noted that the paper negatives display a Sabbatier effect that begins to appear within a few seconds of peeling off the print (and exposing the negative surface, still coated with developer gel, to light and air); areas that started out white (presumably with undeveloped halide) turn gray in exactly the same patterns I'd expect in a developer-wet print exposed to light. I presume this doesn't happen with Type 55, and I'm curious how the process differs between the two to prevent undeveloped halide in the negative, still wet with developer, from darkening -- or, since it's this silver that should produce the print, what's turning dark in the 667 paper negative, even in areas that are full max black in the print? Or would the 667 negative lose or not develop this Sabbatier appearance if it were promptly put into a clearing bath like that recommended for T55 negatives?

I've read lots of descriptions of how the Polaroid B&W print process works (I read the first one in about 1966), but this detail seems to be left out, because I've never read a description that includes the difference between the common print films and the pos/neg materials. Not really critical to anything (the stuff works if used as recommended, which is the main point) other than my curiosity...

I don't know why you got that sabatier effect on those prints, but I've not had that happen to any Type 55 prints in that short a time frame. I've seen Type 55 prints degrade noticeably after a few days or weeks if you don't coat them. The negatives do require thorough washing and hypo-clear if you want them to last, but otherwise are fine. It is my understanding that the developer gel in the type 55 polaroid, like in the other peel-apart films, is basically self-exhausting AND self-fixing. How or why that happens, I don't know. I'd try to get an answer for you, but since Polaroid restructured, everyone I know in their sales or tech departments has been retrenched.

I've used the Type 55 quite a bit and I love it, especially the negatives. Following a reomendation from the Ansel Adams book on Polaroid, I do fix the negs. I've never had the problem you've indicated when exposing for the print.

I'm suprised noone else has answered this, so I'll throw out my 2 cents worth...

The effect you see on the papaer neg is fairly normal. The paper negs are not a true 100% "negative" and will react that way when there is a bit of developer left. If you let it process twice as long you might not see it. I really don't pay too much attention to the paper negs so I couldn't say more? They really have no value other than an obscure art form of themselves when underdeveloped and underexposed (I think) in the art world. There's info about doing that on the Polaroid web site...

And as to Type 55. It's a whole different story. It containes a true negative. At the end of it's processing time, the chemicals are 100% used up, or close enough to it to count. What you get is a fully processed print and a fully processed true negative. The negative must be cleared, recommended in sodium sulfite solution. It can be fixed as mentioned buy doesn't need it. The print & neg do have different speeds though so it's next to impossible to get both a useable print and neg. You have to chose which one you want when you shoot it.

So, there's little comparison between Types 667 and 55 other than the Polaroid process itself.

And when you try Type 55, you will be happy. The neg is just simply beautiful...

OK, here's the answer: Several years ago the developer was changed slightly to reduce or eliminate the Sabatier effect in T-55 film.