Thomas Dean Posted November 18, 2009 Share Posted November 18, 2009 Did a search on "forge welding flux" and there were 192 hits....might want to check them out as you don't have to wait for your answer. Quote Link to comment Share on other sites More sharing options...
Jymm Hoffman Posted November 18, 2009 Share Posted November 18, 2009 If you are using coal or charcoal (real hardwood charcoal,) you should be fine with 20 Mule Team. If you are using gas, then 4 parts anhydrous borax and 1 part boric acid works better for me in my gas forges. I can use this mix in coal or charcoal as well. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted November 18, 2009 Share Posted November 18, 2009 A lot depends on if you are welding up billets for pattern welding and using higher alloy steels in them; or if you are doing "drop the tongs welds" on regular items. If you are billet welding with chrome or Ni steels you may need a much more aggressive flux and you don't want ones with iron filings in them. If you are just doing regular welding then adding boric acid to your borax may help. Quote Link to comment Share on other sites More sharing options...
jimkb8tbi Posted November 19, 2009 Share Posted November 19, 2009 I use a mixture of boric acid and iron oxide 1:1 by weight which costs me $10 for 5 lbs of each ingredient, plus $12 for shipping from Continental Clay Co, in minneapolis. Gave 5 lbs to our local group, Max Carey Blacksmith Guild, for use in our classes. Works good. I do not think scale is the same as iron oxide because this stuff is red and scale is black. The difference lies in the valence state of the iron.(I think) Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted November 19, 2009 Share Posted November 19, 2009 I think mud dauber's nests was mentioned in "The Fox Fire Book" vol 5 (6?) one on ironworking. Clean quartz sand was a traditional flux for real wrought iron. There is a point where borax has done all it can and get's "crusty" and needs to be removed and fresh stuff added. Black crap oozing from inside of cable can be tar/oil/grease/plastic used inside cables. Dr Hrisoulas once published this flux recipe---he calls it "steelglue" "Flux mix is as follows: 5 parts anhydrous borax 2 parts powdered boric acid 1 part powdered iron oxide (the real STUFF NOT the concrete dyes) 1/2 part Flourspar 1/4 part sal ammoniac This stuff sticks most anything together" Quote Link to comment Share on other sites More sharing options...
blksmth Posted November 20, 2009 Share Posted November 20, 2009 If you want colored flux, use iron oxide powder. It comes either red or black and can be purchased at pottery supply houses. It doesn't cost much and your flux is much prettier than plain old white or grey. It might even help. Some commercial flux contains it, especially flux used for gas forges, but I use it in my general all purpose flux. I don't know how much to use. Just mix until you feel good about it. If you don't care about pretty, you can forget it. Quote Link to comment Share on other sites More sharing options...
blksmth Posted November 20, 2009 Share Posted November 20, 2009 Oh, I forgot. The other ingredients are anhydrous borax with about 10% boric acid powder. Quote Link to comment Share on other sites More sharing options...
Titan1921 Posted November 24, 2009 Share Posted November 24, 2009 Being new to this can you guys tell me where I can start to look for Boric acid? Thanks Quote Link to comment Share on other sites More sharing options...
pkrankow Posted November 24, 2009 Share Posted November 24, 2009 Boric acid - Wikipedia, the free encyclopedia It is in pharmacies as a soak, expensive. It is also sold as roach powder, but read the ingredients carefully and make sure of what you are getting. Phil Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted November 24, 2009 Share Posted November 24, 2009 New roach-prufe is 98% boric acid and 2% colouring agent. Old Roach-Pruf was 100% boric acid. I get mine at the old fashioned hardware store in town here. Quote Link to comment Share on other sites More sharing options...
darton Posted December 2, 2009 Share Posted December 2, 2009 can i make flux at home Quote Link to comment Share on other sites More sharing options...
LDW Posted December 2, 2009 Share Posted December 2, 2009 Have you got dirt dobbers in Australia? I have heard stories that the old blacksmiths would grab a dirt dobber nest and forge weld with it. I did a search on the web and found this statement. Dirt Dobber nest with the larva removed and the rest crushed to almost a power. Quote Link to comment Share on other sites More sharing options...
Doug C Posted December 2, 2009 Share Posted December 2, 2009 Very fine sand was used on wrought iron. I am not sure if it would work on modern steel. Anyone ever try this? Quote Link to comment Share on other sites More sharing options...
pkrankow Posted December 2, 2009 Share Posted December 2, 2009 3 "safe" choices in order of aggressiveness: (least) Silica sand (often sold as play sand) Borax (20 mule at grocery store or anhydrous frit) Boric acid, often sold as roach powder, or as a soak powder in the pharmacy, look up first since it has several commercial chemical names. (more) Those are your three "safest" choices. Check the MSDS on these chemicals (search google) and check the msds on several commercial fluxes too. You can mix 1-4 parts of a weaker with 1 part of a stronger for "better" results, or use straight. This is based on many common recipes. A large number of smiths use borax (20 mule) and nothing else, it does foam a bit before wetting out since a lot of water is bound into the molecule and gets driven off. You can also add "iron" or steel filings, and ground scale or iron oxide powder (available at pottery suppliers for mixing glazes). These additives are not desirable for pattern welding. There are stronger and more aggressive fluxes but they also produce more toxic fumes. Unless you are welding stainless or nickle alloys you shouldn't need them, and you may not need them with proper preparation on those alloys. Use the search box in the top bar to look for more threads on flux. This is a well discussed topic. Phil Quote Link to comment Share on other sites More sharing options...
rawtiron Posted December 2, 2009 Share Posted December 2, 2009 As far as borax goes in New Zealand. You can buy pentahydrate or decahydrate. Penta meaning 5 ppm (parts per molecule of water) , or deca meaning 10ppm. So the 5 is better as it has less water. You can buy these at certain chemical supply outfits. Should be the same in Aussie. Anhydrous (dried borax) seems pretty rare here, but was able to be ordered. Jason Quote Link to comment Share on other sites More sharing options...
easilyconfused Posted December 2, 2009 Share Posted December 2, 2009 I've heard of some japanese smiths using charred rice straw. Anyone able to confirm that it works? Quote Link to comment Share on other sites More sharing options...
pkrankow Posted December 2, 2009 Share Posted December 2, 2009 Anhydrous borax frit (finely crushed) can be bought at pottery supply places as an ingredient in glazes as well. Phil Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 2, 2009 Share Posted December 2, 2009 The neo-tribal smiths experimented with wood ash as a flux. It may be due to the silicates in it but seemed to work though better for higher temp welding. I'd make a difference between what can work if you are *good* at welding and what helps if you are not... As such dirt dauber's nests, ash, clean sand, powdered glass will work perhaps more to the exclusion of air when the silicates melt and so better for wrought iron and welding done at high temps And borax, boric acid, fluourspar are more aggressive fluxes and so work better with alloy steels welding at lower temps. Quote Link to comment Share on other sites More sharing options...
Rob Browne Posted December 2, 2009 Share Posted December 2, 2009 Just go to Woollies and get a container of borax from the laundry section. Then you are off and running :) Quote Link to comment Share on other sites More sharing options...
darton Posted December 4, 2009 Share Posted December 4, 2009 cheers guys Quote Link to comment Share on other sites More sharing options...
Morlock Posted December 4, 2009 Share Posted December 4, 2009 I have a soft-spot for anhydrous borax - You can convert 20-Mule Team into it by melting it down, then grinding it up into a powder again. I used to do that when I was a student with lots of time on my hands... Watch the Borax glass, it's sharp, and use a proper crucible for the melt - even if it looks tough, an enameled steel coffee-cup will last about 10 minutes with that molten acid in it...:( Quote Link to comment Share on other sites More sharing options...
pkrankow Posted December 4, 2009 Share Posted December 4, 2009 Watch the Borax glass, it's sharp, and use a proper crucible for the melt - even if it looks tough, an enameled steel coffee-cup will last about 10 minutes with that molten acid in it... Sounds like two points from the voice of experience! Phil Quote Link to comment Share on other sites More sharing options...
plane_crazzy Posted December 5, 2009 Share Posted December 5, 2009 Before finding these helpful advises, I went and bought some flux at a welding supply shop. I am however not sure if it is the right stuff. It seems to match the general criteria though. It is peterson fluxes no. 2 high heat flux. first ingredient is boric acid and it contains iron oxide. is this the right stuff or should i shelve the can and go get some 20 mule team borax? Quote Link to comment Share on other sites More sharing options...
Finnr Posted January 2, 2010 Share Posted January 2, 2010 The flux I use for most welding is a 80/20 mix of 20mule borax and roach prufe.The roach powder is boric acid 98% and other stuff two percent. Works extremely well for me. Finnr Quote Link to comment Share on other sites More sharing options...
Glenn Posted January 2, 2010 Share Posted January 2, 2010 There are smiths that do not use flux, none at all. It depends on the way you learned to forge weld, and the materials being welded. It may be worth while to research the reason behind WHY flux is used in the first place. Anyone care to write up an article on flux, why it is used, it's function in a forge weld, and the different flux formulations? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.