Aloha, fun & authoritative answers -- no cost, no registration, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Where the
world gathers for metal finishing
Q&As since 1989

-----

How to make 4% Picric solution?

Q. I need to use saturated Picral (10 g picric acid + 100 mg methanol [affil links] + 5 drops of HCl) to etch plain carbon steel for the observation of carbide distribution. Since picric is explosive, what kind of caution should I pay in making these solutions: fume hood, googles? Also the picric is stored in water, how can I weigh 10 g picric acid out?

Rong Yuan
Research Assistant - Berkeley, California, USA
2004

A. Picric acid is not stored in water, it is stored damp. Most metallographic methods will assume that if you are using AR grade picric, that it is damp and thus the percentage includes the dampness. For your storage, you do want to make sure that there are no dry crystals on the top of the bottle or on the threads. Even nitroglycerine can stand some minimal amount of abuse, but you do need to exercise appropriate cautions as the results of excessive abuse can be a disaster. It is a very good etch for some applications.

James Watts
- Navarre, Florida
2004

Q. While preparing 50 ml 0.1N picric acid solution using 1.1 g of picric acid and distilled water, the solubility seems to be incomplete. How could I dissolve it completely?

Geethu Joy
- Kerala India
November 26, 2012

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: