How to determine if paper is FB or RC?

[j.eff]

I know I shouldn't bother with this, but I can't stand to let supplies go to waste, so...

I've recently gained access to a fully equipped darkroom, but it hasn't been used in quite some time. There's quite a bit of Ilford paper left over from past use, and I don't want it to go to waste. Most of it is boxed, and it's been stored decently, so I think it will be just fine to use. I won't be using it for anything critical; just practice, equipment test, proofs, and instruction.

However, there are several packages out of boxes, and there's quite a bit of 8 x 10 paper in them. I'd like to use it for contact sheets to use it up, but I have no idea if they're fiber, or resin-coated. I have very little experience with FB paper.

Is there any quick and relatively fool-proof way to determine if this paper is FB or RC?

 

[Terry Christian]

The underside of fiber-based paper will look and feel like real paper, with texture. Resin-coated feels more artificial, like plastic.

 

[frank]

Tear off a piece in the dark, put the bag away, turn on the lights, and submerge the piece you've ripped off in water. If it's finer based, it will get floppy. RC stays firm.

 

[removed account4]

it might actually say RC on the box

 

[j.eff]

Thanks for the quick answers! I'll give those a try in the morning.

 

[Loren Sattler]

Also, most fiber paper is double weight which is much thicker than RC paper.

 

[pschwart]

Thanks for the quick answers! I'll give those a try in the morning.

You will never mistake one for the other -- RC paper has a polyethylene coating on both sides. There are other differences, but a visual examination is all you need.