Ilford MGFB Classic Glossy vs Matte

[esearing]

Yesterday I contact printed an image on MGFB Classic Glossy @ 12.5 seconds with equivalent grade 2.7 using enlarger as the light source with the Multigrade 500 head.

Without changing the enlarger I contact printed the same image on Ilford MGFB Classic Matte.
To get roughly the same tonality and contrast I had to bump up my time to 18 seconds (+44%) and use more green filtering for an equivalent grade 2.2.
I ran another test strip on Glossy just to make sure it wasn't a developer issue.

Is that normal for those of you who use both papers? the glossy paper I have is a couple of years old but I doubt it gained speed.

[esearing]

From others experiences, it does seem that matte paper has a significantly different exposure speed than glossy. No one else seems to quantify it, nor does Ilford, but I would expect it to be 30-50% more time needed vs glossy. It also seems to dry down bluer or more neutral than glossy which has the "greenish" cast, and the flatness looks almost like an inked print. They look the same when wet.

[interneg]

It sounds like you're running the MG 500 on a different controller to the stock one. As it is, you will always get some differences between gloss and matte surfaces - especially if you are printing for a perceptual match. And yes, the 5K surface is cooler than the 1K - I've found that it tends to sit between the 1K Cooltone and the 1K Classic. And fog is essentially equivalent to a slight speed gain - it'll impact the toe, hence why you might need to add a little contrast - and there's a considerable difference between just enough fog to have a sensitometric impact and enough general fog to have a perceptual impact.

[esearing]

Thanks interneg - I am using the RHDesigns analyzer to control the MG500 head. I can use the analyzer probe under the negative to get a rough idea of time just like a projected image, and it has a test strip mode which gets me to the print time a bit faster too.

As for fogging you must be reading my mind. In the last couple of print sessions I have tried to expose bright white sky or white water as just a hint of gray vs paper white as a starting base. It does make a visual impact as you suggest. That was how I noted the different time requirement on my test strips because I had to work up to it when switching to matte paper. Not sure how much of a hint of gray I would need to work toward as a standard. I think of it in the same vein as pre-flashing which gets the tones on the paper started.