We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences

FMF English Forum is moderated by John S. White and Peter Megaw
 

Spanish message board






Newest topics and users posts
23 Nov-01:01:01 Re: munich show (mineralientage) 2017 (Roger Warin)
22 Nov-21:43:45 German language magazine (Codydel)
22 Nov-21:33:54 Re: 1929 ed over rocks and minerals article (Codydel)
22 Nov-19:00:30 Re: presentation of new members - reference thread (Peter)
22 Nov-18:59:21 Re: presentation of new members - reference thread (Don Lum)
22 Nov-18:45:30 Presentation of new members - reference thread (Matheustorres)
22 Nov-17:28:46 Re: what is it #3 (Pete Modreski)
22 Nov-16:28:53 Re: what is it #2 (Pete Modreski)
22 Nov-15:28:47 Re: new generation for picture - ploum (Ploum)
22 Nov-15:12:36 Re: the mizunaka collection (Am Mizunaka)
22 Nov-14:22:34 Re: what is it #3 (Pete Richards)
22 Nov-14:02:09 What is it #3 (Andrew Harvey)
22 Nov-13:37:50 What is it #2 (Andrew Harvey)
22 Nov-13:28:47 Re: collection of michael shaw (Crosstimber)
22 Nov-13:20:55 Re: what is this (Pete Modreski)
22 Nov-13:19:46 Re: franjungle collection (Franjungle)
22 Nov-12:56:02 Re: what is this (Andrew Harvey)
22 Nov-12:34:36 Re: what is this (Pete Modreski)
22 Nov-11:54:12 What is this (Andrew Harvey)
22 Nov-07:21:12 Re: new generation for picture - ploum (Ploum)
22 Nov-03:56:24 Re: new generation for picture - ploum (Pierre Joubert)
22 Nov-03:09:39 Re: new generation for picture - ploum (Tobi)
21 Nov-22:04:25 Re: munich show (mineralientage) 2017 (Roger Warin)
21 Nov-21:33:30 Re: munich show (mineralientage) 2017 (Roger Warin)
21 Nov-15:55:24 Re: the mizunaka collection (Philippe Durand)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
35634


The time now is Nov 23, 2017 02:24

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
How to remove iron stains?
  Goto page Previous  1, 2
  Index -> Conserving, Preparing and Cleaning Minerals
Like
5


View previous topic :: View next topic  
Author Message

GneissWare




Joined: 07 Mar 2008
Posts: 1263
Location: California


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Nov 15, 2013 23:40    Post subject: Re: How to remove iron stains?  

Super Iron Out is much safer and just as effective (and maybe more so) as Oxalic acid. One should use the least aggressive cleaner possible when cleaning. Also, I have seen many specimens ruined by using Oxalic acid, leaving behind an insoluble stain of calcium oxalate when used with hard water.
Back to top
Reply to topic Reply with quote
Like
   

Barry Vincent




Joined: 05 Jun 2013
Posts: 27
Location: NSW

View user's profile

Send private message

PostPosted: Nov 16, 2013 00:14    Post subject: Re: How to remove iron stains?  

GneissWare wrote:
Super Iron Out is much safer and just as effective (and maybe more so) as Oxalic acid. One should use the least aggressive cleaner possible when cleaning. Also, I have seen many specimens ruined by using Oxalic acid, leaving behind an insoluble stain of calcium oxalate when used with hard water.


Fortunately , where I live , the water quality is very good. However I'm always playing around with small specimens , so I use demineralised water anyway.
Here in Australia , I"m not sure if there is such a thing as Super Iron Out. I'll have to check this out though.
Back to top
Reply to topic Reply with quote
Like
   

Jesse Fisher




Joined: 18 Mar 2009
Posts: 464
Location: San Francisco


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Nov 16, 2013 02:57    Post subject: Re: How to remove iron stains?  

As I mentioned, oxalic acid likes to turn into calcium oxalate and will pull Ca from fluorite to do so. While it is good for solubilizing Fe oxides/hydroxides, it takes a lot of soaking to get it out of anything porous such as micas or feldspars with a lot of cleavage planes. If any of the solution remains in the cracks then it dries you get a nasty yellow stain on the mineral you have been trying to clean. Quartz, being without cleavages, tends to respond fairly well. Other minerals can be a problem. I always start with sodium dithionite (active ingredient in Super Iron Out) and move on to phosphoric acid if that doesn't remove all the iron stain.
Back to top
Reply to topic Reply with quote
Like
1
   

Les Presmyk




Joined: 06 Dec 2007
Posts: 372
Location: Gilbert, AZ

View user's profile

Send private message

PostPosted: Aug 31, 2015 09:28    Post subject: Re: How to remove iron stains?  

Oxalic acid not only has an affinity for calcium, being acidic means it will attack and dull the calcite. It is the calcium in fluorite the oxalic acid is starting to dissolve. Finally, once calcium goes into solution in the presence of oxalic acid, it begins to precipitate as calcium oxalate, an insoluble compound (also one of the most common versions of kidney stones) that deposits back on the specimen.
Back to top
Reply to topic Reply with quote
Like
   

basti




Joined: 29 Mar 2012
Posts: 6
Location: Brno, Czech Republic

View user's profile

Send private message

PostPosted: Feb 19, 2016 06:25    Post subject: Re: How to remove iron stains?  

Oxalic acid is pretty good but also has some drawbacks:

The toxicity is quite overrated - it precipitates calcium so it can harm you if you eat few tablespoons but thats probably not going to happen. You can put your bare fingers into the oxalic acid solution and nothing happens (same for the 5-10 % HCl btw.). It doesnt produce toxic odour like super iron out and in my experience works much faster.

The bad part is that it is much more aggresive and can harm luster of micas. It should not be used on minerals with calcium as it can produce precipitates of calcium oxalate, which is sometimes difficult to remove. You should use rainwater or distilled water as there is always small amount of calcium in the water = precipitates as a fine "white dust". What I see as a biggest problem with oxalic is the production of yellowish precipitate sometimes, which is very difficult to remove.

SIO or sodium dithionite:

Much more gentle and effective and much slower then oxalic. However it is not all roses too. It is about 5x more expensive then oxalic. It produces toxic and smelly gases = no indoor at all. It is a strong reducing agent, which sometimes recults in formation of green-black coatings which must be removed by citric acid. Sodium dithionite is unstable chemical which decomposes if not sealed from air properly. Do NOT mix SIO with other chemicals except baking soda (sodium hydrogencarbonate) or citric acid!
Back to top
Reply to topic Reply with quote
Like
1
   
Display posts from previous:   
   Index -> Conserving, Preparing and Cleaning Minerals   All times are GMT - 5 Hours
Page 2 of 2
  Goto page Previous  1, 2  

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2017


Powered by FMF