There are many grades of chemicals that are not obvious to someone not familiar with chemistry. I list a few below.
1. Cosmetic grade - usable on human skin, can contain lots of things that do not affect humans such as halides. Not good for photography.
2. USP (US Pharmacopia) which is a grade which excludes chemicals harmful to human metabolism or otherwise untoward effects.
3. Practical - usable in most practical applications.
4. Photographic - usable with no impurities that affect photographic processing or emulsion making.
5. Analytical - so pure that nothing interferes with use in analytical procedures.
Etc. Etc. Etc.
Each has an ISO standard so that individual companies or chemical compositions can be ISO certified.
Any person not a chemist would be oblivious to this all.
In photography there are 3 situations from my POV.
1. Do not care and having fun.
2. Economy and maybe don't care.
3. Highest quality.
Determining your position in these two matrices is essential to getting what YOU want in your pictures. I have said "Use what works for you" but after more than 30 years in the business, I find that variability in the end result increases from 3 > 1 in the above matrix and that photograde and higher is best. Sorry! I've done the tests. It is a 'fact' to me.
So, having a person suggest something to me says to me that he had better be an expert in the entire system and should have quantitative results. This is generally not the case. It is expressed as an 'opinion' by a self proclaimed 'expert' and I am, as I have said before, becoming less and less tolerant of these self proclaimed experts.
So sorry to interject this into what has been a 'fun' thread, but it is now on the verge of diverting good people from fact.
Ummm, what did you do? At this point I have not quoted my education or achievements. FYI:
Originally Posted by gainer
1. Gotten a graduate degree in chemistry
2. Been in intelligence in SEA and hold a retired officers rank.
3. Been Still Photo Director at Cape Canaveral
4. Been Asst. MoPic and Metric Photo Officer at Cape Canaveral
5. Been part of the development team for Ektacolor 37 and 30 paper
6. Designer of the current Kodak Blix.
7. Codesinger of the EP2/3 developer
8. A member of the Gold 400 team
9. A member of the Ektaflex team
10. A member of 3 products that were not released including one based on Cuprous oxide and a thermal dye bleach system with Grant Haist.
11. A member of the emulsion modeling and scaling team.
12. A holder of 15 patents and 6 Research disclosures on photo products.
13. Last but not least... Kodak has publised a CTO newsletter article about my emulsion work, and I have been teaching workshops in emulsion making and coating.
I think that this defines my use of logic and education Patirck. You see, I can put up my CV too. I have been devoting my retirement to QUALITY photo education in terms of chemistry and lab techniques.
My CV can beat up your CV with the punctuation tied behind its back.
no it can't
yes it can, and on Sunday too. nah nah nah.
Come on guys this got silly several pages ago.
Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI
So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004
I could not agree more.
I'm just waiting for a hockey game to appear out of nowhere
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Is this the APUG version of Godwin's Law? http://en.wikipedia.org/wiki/Godwin's_law
Originally Posted by Anscojohn
This seems to happen every time that a few people are debating some technical detail that is deemed too esoteric for some other disinterested parties to bother with.
Well, I hereby declare "Keyes' APUG Corollary":
As an APUG discussion grows longer, the probability of someone saying, "Why don't you guys go out and make some photographs?" approaches one.
It is indeed silly. I cannot get an answer to the question "What makes using 20 Mule Team Borax in photographic solutions a risky business." It ought to be straightforward, lke "It contains such and such." What I get is that although it may have the same percentage of the borax decahydrate as analytical reagent grade, it may not be good for some unknown but possible reason. Should anyone need an advanced degree in chemistry to understand a straight answer to that question? Is it possible for less than 1% of a substance to have something other than chlorine, phosphates or abrasiveness that might suddenly jump out and bite my emulsion, and not to know the probability of that substance being in a product that is produced at a rate greater than 100,000,000 tons a year, and with a uniformity great enough that its solubility vs. temperature curve can be published to the 1/100 gram/liter? I doubt that the organic developing agents we use are manufactured to such tolerance, and our measurements with any balance we are likely to afford will weight to such precision and accuracy.
Beyond determining what impurities might affect our developers, there is nothing unique about chemistry that prevents me, whose knowledge of chemistry you have not tested, from questioning the wisdom of paying extra for difficult to obtain chemicals about which we have only someone's word.
Ther is an innate, and I do mean inborn, difference between an engineer and a scientist. You are seeing them clash.
Yes, but it doesn't explain why you are not using them now. I put mine up because you called me an aeronautical engineer because I got a degree with that title, and in fact I never worked as an aeronautical engineer. I began as an aeronautical research scientist, which I think parallels your work at Kodak. I ended as a human factors "expert". I was an engineer in my approach to problems, and the problems I was assigned to work on were each different, from analysis of wing loads in flight to analysis of supersonic wind tunnel data, to design of star charts, to design of a planetarium projector, to basic human factors studies to design of an oculometer for determining in real time a pilot's lookpoint. I mentioned one of two photographic tasks I was assigned.
Originally Posted by Photo Engineer
I still do not see why one of our chemists cannot define the differences that make the analytical reagent better than the mule crap for use in black and white developers.
Patrick, I'm not going to quote my education and work experience as it will not convince you of anything. Your acheivements are much greater that I'll ever hope to reach. Ron, your's are too.
Originally Posted by gainer
But Pat, let's talk engineering. Say I'm building a rocket to put a satellite into a particular orbit. My design criteria is to be able to reach orbit without blowing up. Well, at the least only one catastrophic failure out of every 100 launches.
So we need to use some steel in the framework of the structure. The specification that the design engineer came up with specified a Ni-Al-Ti superalloy. Well, some other engineer down the line figures that we can get by with SAE 4340 steel. He figures we don't need all that high temperature strength and makes a materials substitution. We just don't need that much performance, he thinks to himself.
Well, that material substitution works. Well, most of the time. We have a failure rate of 5 catastrophic failures out of every 100 launches.
Was this good engineering? Was it worth the risk?
And what if the rocket had met our 1 failure out of 100, but the rocket was not able to reach as high of orbit as we wanted? It made it to orbit, it did not blow up more than expected, but it just did not give us the performance we needed. The satellite could not get into the proper orbit.
And what if we did not have the tools to measure that lack of performance. Is it still good engineering?
These are the kind of questions involved in this debate, as I see it. Especially the last question I've posed here.
It's simple. I don't know the details of Technical Grade vs. Photographic Grade vs. ACS Reagent Grade. How can you expect me to state that all three are suitable for the task at hand without knowing the specifications of each? Isn't that a large part of engineering? Understanding and meeting specifications?
Originally Posted by gainer