How is this effect achieved?

[Lttr Prssd]

On old posters like this? That rainbow effect. Is it silkscreened? And is it called split-fountain or something like that?

[steve w]

split fountain, yes.
one screen, 3 different ink colors that blend as you print

[andydiesel]

yup

[Lttr Prssd]

Cool. Thought so but wasn't sure. Could it be achieved via offset printing as well?

[VonDada]

On old posters like this? That rainbow effect. Is it silkscreened? And is it called split-fountain or something like that?

I think these are offset. I could be wrong. I have an old telephone pole poster from the 70s and it doesn't look screenprinted.

[steve w]

I don't know if it can be done offset or not (as a split fountain anyway).
There's a screenprinting company around here that still prints them.
Globe Printing, I think

[Lttr Prssd]

Thanks guys.

[Andymac]

that is offset. split fountain refers to mixing the inks in the fountain resevoir (there are little dials to control the ink flow along the length)

the result is as you see it on the poster. It was a common way of getting more colours into a poster, can also be used with no blending, just running (for example) some black type at the top and some red type at the bottom. Same plate, same print run, two colors.

The effect in screenprinting is acheived by dumping the inks in the puddle and tapering them into each other to get the blend going. there are some process threads on this somewhere

[DenisMutter]

If that poster is legit, it should be a letterpress poster, and the bottom layer would have been inked via a big roller thingy.

or something.

oh.

sorry. I thought I had something helpful to say.

[JustinHelton]

If that poster is legit, it should be a letterpress poster, and the bottom layer would have been inked via a big roller thingy.

or something.

oh.

sorry. I thought I had something helpful to say.

No actually thats what I was gonna say as well....Its probably a generic offset poster, but its imitating a letterpress style.