A press will exhibit different dot gain with silvermaster plates depending on chemistry strength in the plate processor. Although the newer silvermaster CTP units can be calibrated visually with a test plate it is something that must be done on at least a weekly basis. Silvermaster chemistry MUST be changed at least every 4 weeks because of residue buildup in and oxidization of the chemistry. The press should have it's rollers adjusted for optimum stripe to the plate as well. On a Ryobi 3302 3mm give or take 1/4 millimeter for all 3 ink form rollers is about normal. The water roller is about 2.5 to 3 and can be adjusted on the fly to compensate for excessive or to little water cleaning at image/non-image boundries. An out of spec roller stripe (to fat) to the plate can fill in a more solid tonal area. An excessive plate to blanket pressure can cause more dot gain. Also excessive blanket pressure to the substrate can cause more dot gain. Also I disagree with your beginning solid density reading. Status T SWOP spec values are what I usually use and Process BLACK on Gloss coated 100# text is 1.75 to 1.80 density and on non gloss 60# text it should be 1.20 to 1.25 density. The dot gain of a press is important to set the press curves of the plate output device for accurate halftone and screen color reproduction. On a 4 color or more press (CMYK or Hi-Fi/Hexachrome) this must be repeated for every color. Sometimes twice depending on the rip software. Some rip software likes to have a second test print done from the first test prints dot gain curve then you input the new dot gain numbers in order for the software to further refine the curve.
Very informative and a great source of information. I just want to point something out to help anyone who's a little confused like I was. The measurements he's making are of dot area as it says on his densitometer display. Dot gain values are hardly important when it comes to plotting curves and such, but it's because of dot gain that we want to plot these curves. Dot gain = output dot area - input dot area Anyways, when you create your dot % curve in Photoshop or a rip, it's concerning dot area, although the need is because of dot gain in print. Maybe this is obvious, but it took me a bit to know. And also, many people may not know that you can change the curve settings to read dot area % in Photoshop.
I am trying to learn the very basics of this. I want to have a black half tone workbook printed on uncoated paper. I thought dot gain was a bad thing but when looking at the images on sheet that is printed, it is the 20% dot gain images that are better. So I am thoroughly confused. I need to understand this so that when I design the workbook in InDesign I know what value of black to give different areas. Do you know of a video, book or article that will explain this to me in simple terms? If I want the offset printed result to look like say a 65% black... I should account on the dot gain and design the line at say 45% ? Am I understanding this correctly?
@@moonbee03 If I'm not mistaken, it sounds like you want to look into soft proofing or curve adjustments. That way your screen representation can match the physical output.
@@AwakenedAnhedonic Perhaps the soft proofing... I will not be using images per say. Just areas that are at a 15% etc. Thank you for taking the time to read and understand my question!
Very informative.. 👍👍👍
A press will exhibit different dot gain with silvermaster plates depending on chemistry strength in the plate processor. Although the newer silvermaster CTP units can be calibrated visually with a test plate it is something that must be done on at least a weekly basis. Silvermaster chemistry MUST be changed at least every 4 weeks because of residue buildup in and oxidization of the chemistry. The press should have it's rollers adjusted for optimum stripe to the plate as well. On a Ryobi 3302 3mm give or take 1/4 millimeter for all 3 ink form rollers is about normal. The water roller is about 2.5 to 3 and can be adjusted on the fly to compensate for excessive or to little water cleaning at image/non-image boundries. An out of spec roller stripe (to fat) to the plate can fill in a more solid tonal area. An excessive plate to blanket pressure can cause more dot gain. Also excessive blanket pressure to the substrate can cause more dot gain. Also I disagree with your beginning solid density reading. Status T SWOP spec values are what I usually use and Process BLACK on Gloss coated 100# text is 1.75 to 1.80 density and on non gloss 60# text it should be 1.20 to 1.25 density.
The dot gain of a press is important to set the press curves of the plate output device for accurate halftone and screen color reproduction. On a 4 color or more press (CMYK or Hi-Fi/Hexachrome) this must be repeated for every color. Sometimes twice depending on the rip software. Some rip software likes to have a second test print done from the first test prints dot gain curve then you input the new dot gain numbers in order for the software to further refine the curve.
Very informative and a great source of information. I just want to point something out to help anyone who's a little confused like I was. The measurements he's making are of dot area as it says on his densitometer display. Dot gain values are hardly important when it comes to plotting curves and such, but it's because of dot gain that we want to plot these curves.
Dot gain = output dot area - input dot area
Anyways, when you create your dot % curve in Photoshop or a rip, it's concerning dot area, although the need is because of dot gain in print. Maybe this is obvious, but it took me a bit to know. And also, many people may not know that you can change the curve settings to read dot area % in Photoshop.
And the dot area % to RGB conversion formula is:
255 - (2.55 * dot area value)
I am trying to learn the very basics of this. I want to have a black half tone workbook printed on uncoated paper. I thought dot gain was a bad thing but when looking at the images on sheet that is printed, it is the 20% dot gain images that are better. So I am thoroughly confused. I need to understand this so that when I design the workbook in InDesign I know what value of black to give different areas. Do you know of a video, book or article that will explain this to me in simple terms? If I want the offset printed result to look like say a 65% black... I should account on the dot gain and design the line at say 45% ? Am I understanding this correctly?
@@moonbee03 If I'm not mistaken, it sounds like you want to look into soft proofing or curve adjustments. That way your screen representation can match the physical output.
@@AwakenedAnhedonic Perhaps the soft proofing... I will not be using images per say. Just areas that are at a 15% etc. Thank you for taking the time to read and understand my question!
Very nice! Thank you!
You are grate. Thank you