Thread: My razor is too sharp???? I like a duller edge??

Good point about crystal shape, diamond vs the round shape of Chromium Oxide.

The points made above about purity are important. Paraphrasing, if the average particle size is 0.5 micron, but there are significant numbers of particles ranging up to 2 microns, then all bets are off! I asked Kremer Pigments about this very point. I am including their reply below.

Basically, they guarantee a high level of purity. So, if there are larger (or smaller) particles, there aren't many. But, they do acknowledge that larger particles exist, because if I understand correctly, residue is left after sieving.

My only other comment about the 0.3 micron Kremer Chromium Oxide is that EVERYONE who has used anything by Kremer believes that they produce very quality products, with a very high level of purity. After spending a long time with my microscope viewing a blade after 0.25 diamond, 0.5 chromium oxide and 0.3 chromium oxide, and lately 0.09 micron iron oxide, I have to agree that the Kremer products are quite pure.

Here's their letter...

Hello Larry,

Our chemist in Germany which answers very specific questions, Eva Eis, forwarded this email which she thought she previously sent you. I have attached it to the body of this email.


Dear Mr. Andreassen,

I am sorry, but we don´t have any data about largest and smallest
particles. It is difficult to measure these fine pigments and usually only
the predominant particle size is given. Agglomerates may be larger, as you
can read from the sieve residue of 0,02% in a 45µ-sieve. Purity of the
pigment is approx. 99%.

Best regards,
Eva Eis
Diplom-Restauratorin


We definitely recommend tests prior to the final application, we can not
guarantee for any instructions given.


--
Kremer Pigments Inc. NYC

Phone (212) 219-2394
Fax (212) 219-2395
1 (800) 995-5501

USA Store Location:

247 West 29th Street
New York, NY 10001
(Btw. 7th & 8th Aves.)
Open:
Monday - Saturday 11:00am - 6:30pm

Ultimately, magnification is not just about the lenses. You also have to factor in the camera resolution, as well as screen size and resolution for the viewer. I'm looking at this thread on a 15.4" laptop, someone else may be using a 26" monitor, the images are going to be different sizes depending on this and screen resolution, thus effective magnification is different.

Does yuzuha post here? She had this all explained a few years ago, but it's not something I know all that well.