Hey everyone! 

Yesterday I experimented with forging a candle holder from a piece of pipe. To give the upper part with the candle a little bit of a outstanding finish I tried to dip the hot and brushed forging in molten aluminum. Unfortunately the aluminum did not adhere to the steel as I thought it would. The wetting of the steel wasn't very uniform. So I tried brushing it after dipping which gave a nice effect too. 

Even though I'd like to have a uniform coating. Are there any tricks to achieve this with aluminum and steel? 

I don't know any tricks to make the two metals stick better, but I really like the effect of the brushing you did.  If you're making more candle holders, I'd do the same thing again.

 

If you really want a more even appearance, you could do some experimenting with some scrap pieces of steel.  Try using soldering flux (carefully in melted aluminum, not sure if it would boil like water) and maybe different temperatures of the steel.  

 

 

Have you thought about trying Tin/pewter? It would adhere much better than aluminum. 

It might adhere better if you were to grit blast it before dipping.  It would have a rougher surface to which the Aluminum could adhere.

Thanks for your answers so far! The steel was not heated too much before dipping. I had a good heat on it, brushed it to get all the loose scale off and dipped it. Maybe it was too smooth to stick properly...

I also thought about putting borax on before but not sure if it will work as a flux with aluminum. With brass it should work better as it is basically like brazing. 

They make fluxes for joining aluminum.  Might be worth looking into those. 

Have you check to see how well the aluminum you've stuck to it is stuck? You might check with a welding supply, IIRC there are brazing rods made for AL, one of those might adhere to steel and might even be a good enough color match to do what you want. If not it should provide a surface AL can bond to.

Frosty The lucky.

From what I know about the process, the steel has to be very, very clean and they normally either use a high silicon alloy (about five to ten percent) or relatively pure aluminum.  Don't know if they clean using pickling or mechanically. You also don't want it much above the melting temperature of the aluminum. I believe they normally dip at about 1300 or so.

I've experienced this a bit in casting; I usually use a steel spoon wired to the end of a mild steel rod when removing dross and making sure everything is melted. If the aluminum is too hot, it runs right off, but if it's not too hot, it will tend to freeze and adhere to the steel, although this is at least partly a mechanical lock