Please Clarify My Poor Maths For Developer Dilutions

[IanBarber]

I am just reading a book whereby the author states... "1 part HC-110 stock solution to 17.5 parts water.". Is this the same as saying 1:17.5

Example. For 1000ml of chemistry, 54ml of HC-110 and 946ml of water.

Have I git this right ?

[koraks]

Yes, I read it the same way.

[Kevin Crisp]

The confusion is in what exactly the word "stock" means. Many instructions have you diluting the syrup to get a "stock" solution, then diluting that to get to various known concentrations.

I have found it easier to just do the math and get a small accurate measure for 1 ml. One ml of the syrup with 31 ounces of water = one quart (32 oz) of Dil B.

[IanBarber]

Thanks for quick replies.

Further down as I read I see he says.... "Follow Kodak’s recommendations for mixing the stock solution from concentrate, then dilute as follows..." "1 part HC-110 stock solution to 17.5 parts water"

[Kevin Crisp]

Yes, it has confused many. There is stock and there is stock. A lot of times people talk about stock when they mean the syrup. Which isn't the same thing with HC110.

[Jerry Bodine]

...One ml of the syrup with 31 ounces of water = one quart (32 oz) of Dil B.

Kevin, sorry but you're mixing up your units (adding ounces to ml). To get a working solution of 32 oz you'd add 31 oz of water to one ounce of concentrate, rather than one ml of concentrate. Since Ian is in the UK where metric is used, he would get one liter of Dil. B working solution by adding 969ml water to 31 ml concentrate. 1:31

https://web.archive.org/web/20150214232847/http://www.kodak.com/global/en/professional/support/techPubs/j24/j24.pdf

This link explains Kodak's definition of "stock" in a footnote as a 1:7 ratio of concentrate to water; this stock is then diluted further to get a working solution. Most folks prefer to mix the working solution straight from the concentrate and bypass the stock preparation, measuring out the concentrate into a one liter container - then rinsing the viscous concentrate out of the measuring device into the container to make sure all the concentrate is used - then add water to make one liter. The pdf provides tables for each method.

[IanBarber]

Nice resource Jerry, thanks for that, my question has now been answered

[IanBarber]

On a side note...

How low can you safely go with development time before it becomes an issue.

Let's say that Normal development time is 6.5 minutes and you want to do N-2 to tame the high values which could mean lowering the development time to under 5 minutes

[Liquid Artist]

One thing that I love about HC-110 is that you can pretty much fine tune it to meet your developing needs. Want a longer developing time mix up a weaker dilution.

Plus Kodak actually has PDF's available online for most of their current developers.
http://imaging.kodakalaris.com/sites/prod/files/files/resources/j24.pdf

[Doremus Scudder]

On a side note...

How low can you safely go with development time before it becomes an issue.

Let's say that Normal development time is 6.5 minutes and you want to do N-2 to tame the high values which could mean lowering the development time to under 5 minutes

Ian,

Development times shorter than five minutes are generally not recommended due to the danger of uneven development. With HC110, you can simply make a half-strength dilution and come really, really close to doubling the earlier development time. E.g., if your time is 6.5 minutes with dil. B (syrup 1+31), then you can dilute 1+63 and develop for 13 minutes and get essentially the same results. So, if your N-2 time is, say 4 minutes, just dilute your developer at half-strength and develop for 8 minutes.

Caveat: be sure you have enough concentrate in your final developer volume to develop the area of film you have.

Best,

Doremus

[IanBarber]

So, if your N-2 time is, say 4 minutes, just dilute your developer at half-strength and develop for 8 minutes.

Thanks Doremus. If you are using another developer for example, XTOL and your N development is say 6.5 Minutes, what would you do inn this situation if you needed a N-2 development baring in mind 6.5 minutes is so close to the 5 Minute threshold

[Liquid Artist]

I don't know if all developers are as robust as hc-110. In some cases they may be ineffective when they're diluted that much. You can always try a scrap sheet.

In some cases you could also use a colder solution to extend developing times.