Below is a summary of some of the many questions that have been asked over the years. I have also included some of the many "tricks of the trade" I have learnt and methods I have encountered on the way. I hope you find this all helpful with your quest to master the welding of alloys. Sorry if I seem to repeat myself as these steps are very important. Best Regards, Lance.

Magnesium:
Is the item you are trying to weld melting before the rod?
I would take a guess that the part that you are having trouble welding has or may have a Magnesium content. The item to be welded may start swelling or just fall apart when heated. I have welded the door strikers on my 38 ford, having to hold the heat back and bring it up to temperature very carefully and then back the heat off as soon as the rod adheres...a very fine line as it starts to bubble and pop as the muck/magnesium within explodes. Supporting the item or encapsulating the outside walls will stop the item falling apart.
You can use durafix as a casting rod...use casting sand, exhaust putty or mild steel (panel-steel) as a mould or support.
My saying is "if it's pure magnesium - glue or chuck it out!

Chrome over Durafix:
Yes Durafix can be chromed over, it is recommended to use the triple chrome process (real chrome) that utilizes a nickel coating. The nickel coating hides the scar-line created by the slightly different density metals. The rod is well suited to zinc based or aluminium with a zinc content or even dissimilar aluminium alloys. The welds are very strong and free of porosity. As scar-line can also occur when anodizing and thus be eliminated with the same process.

Boat Repairs:
Yes Durafix is the Ideal product for Marine repairs, 25% of our worldwide sales are specifically used in marine application. Imagine being on a coral atoll or Pacific Island with a hole in your ali boat and no three-phase power or tig welder in your back pocket! The Unique Durafix welding process utilising LPG or low heat source is a real saviour!
Lots of guys always ask about their little Propane torch (cigar lighter?). This is a hard subject to give advice on when I can't see or measure the maximum heat output. I always say rule of thumb "providing you have sufficient heat source e.g. a reasonable sized LPG torch of commercial nature or an oxy/acet set using a neutral flame for thicker hulls of 4-5mm".
It's always hard for me to guess the exact thickness of a hull and if there is any intersecting ribbing (bracing) behind or near the weld area, this is important because heat sinking can occur (heat being absorbed faster than the torch can put out). A small torch may not keep up with the immediate cooling….so a larger commercial LPG Torch unit or Oxy/Acet Set will be required.

Use the S/S wire brush supplied to eliminate oxidation. Grind surface (sanding disc), heat and wire brush (s/steel brush only) to eliminate salts and contamination. Proceed to tin surface with Durafix repair rod, re-brush, scrub or flick the molten rod this will drag further oxidation out of the Aluminium and then re-apply Durafix! Stirring the weld is very important and will be the success or failure of a weld. The stirring action brings oxidation to the surface (just like slag in a steel refinery).

Large holes or cracks can be covered by plates or patches of aluminum providing the pre tinning, brushing and re-applying durafix to each surface before sweating together.
A hole can be filled in from the topside or inside of the hull. The hole must be covered by a piece of 'panel steel' on the underside of the hull when Durafix is applied or run through from the inside. Remember there are three absolutes in life, Death-Taxes-Gravity! Gravity and molten metal are at odds with each other, this is why alloys are cast in molds.
Always make sure all hole edges are completely wire brushed both sides and pre-tinned with durafix first. The rod will flow through and end up against the panel steel leaving no porosity. Remove the patch then regrind flush or into shape. Again you must prep both sides as per above before trying to use a piece of panel steel to the block hole. Always stirring the weld 3-4 minutes from the topside as the stirring brings oxidation to the surface. You can use the standard etch-paint process over Durafix such paint systems employed when painting aluminium marine items and craft.

Marine Corrosion - Pinholes:
Durafix along with all other brazing type products or soldering systems "will not run into or penetrate hairline cracks and pinholes". The rule is "Durafix will not adhere to any aluminium surface that has not been sufficiently cleaned, ground and then brushed with a Stainless brush"!
Slightly ream out the pin holes so it has a wider surface area, use a large (wide tipped) drill very slowly…don't drill right through. This will give you a nice clean surface and enable the S/S brush to "get in".
Wire brush (stainless) all areas, with a bit of heat first (this opens up the pores of the aluminium), when the Alloy is hot enough the rod will then melt on the hull, don't overheat the rod (or hull!!!!!!) Aluminium will hold the heat well, so start to back the heat off intermittently when the rod starts to melt, brush the molten rod, then re-apply….sort of doing it twice…."tin it then do it again". This drags out the oxidation and creates a very strong bond…..miss out this step and your weld will be weak (bird s*#*t)!
Durafix is much denser, stronger and free from porosity, therefore is well suited to any submersion in saltwater.

Model Fabrication:
Durafix is well suited to DIY (and professionals alike) to build models, model aircraft framing and such likes as fabricating small tubes items together, light plates, or casting etc. Durafix is well suited to the lightweight exhaust systems for model craft, Durafix being the only weld system able to join paper thin (beer can wall thickness) aluminium!
Too easy! You will only require a small heat source or small DIY torch for such welds.

Casting:
Use DuraFix to cast small tricky items that may be hard to shape. Use greensand-casting sand or exhaust putty to produce the shape.
I have made a small (micro) open ended spanner by flowing Durafix into a dried open mould made of exhaust putty sitting on panel steel. I believe you could make auto badges the same way.

Extruded Aluminums:
I have noted with experience that extruded alloys in particular have a highly polished surface thus trapping contamination within the pores of the Alloy. Unless the tinning process described below is followed poor welds are produced.

• Durafix will not adhere to any alloy surface that has not been pre-brushed with a S/S wire brush (even if you grind it). All other brushes will not work.
• Sand, grind, vee then using bit of heat (opens the pores due to expansion) followed by a vigorous stainless brushing (stainless brush only), coat the surface with durafix not allowing the overheating of the rod or alloy and then BRUSH or "flick" THE MOLTEN ROD OFF AND THEN RE-APPLY DURAFIX. This step acts as a type of tinning process allowing the contamination to be dragged out of and durafix to enter the now clean pores of the aluminium. I recommend purchasing our large brush as the molten rod can clog-up the finer small tooth-brush sized S/S brush.
• The "stirring and rubbing motion" of the near solid durafix rod also helps with bonding. It is important not to over heat the rod, allowing the surface heat within the parent metal to melt the rod (not the torch). Back the heat off (in and out motion) as soon as the rod melts as the small 200 degrees window of heat (causes over heating) will start to crystallize the welds and produce a weak weld or non adherence.
• Also note when a foundry produces molten metal the slag or contaminants float to the top. So when the weld is cool another S/S brushing on the top of the now solid weld (tinning process) will remove the contamination before proceeding to the "second time round" weld…this does produce much stronger welds and is recommended on those loose alloy boat rivets and (salt infested) cracks.
• The problem can be very similar with cast aluminium. The same process as above before joining the parent metals. Die-cast, when broken looks very grainy and I have found the parent metals always need a surface grind or filing before attempts to rejoin. I have joined some pretty crappy die-cast e.g a fat soaked handle of a meat processing machine in front of an engineer…we gave it the vice and hammer test…the customer was blown away with the strength of the weld when the die-cast broke elsewhere.