PT test

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From my welding days, I remember a dye penetrant that was used to locate hairline cracks.  Anyone know the ingredients for a 'homebrew' I could make to do the same thing? (I'm not being cheap, just live an hour from the nearest welding supply shop.)  Thanks.
Reply:Don't know what the "real" PT penetrant is, but I'm thinking a very light oil.  And the developer would be a fine partical absorbant like talc or cornstarch.As I recall,1.  Clean first.   Try acetone, let it evaporate2.  Apply penetrant.  Try a very light oil like transmission fluid or brake fluid that is colored?3.  Wipe off surface excess.  Try final wipe with acetone damp cloth,4.  Apply developer (talc or corn starch).  Wait for oil to bleed out of cracks into developer.
Reply:Whats it on? If its steel and in an area you can heat and you have a torch......
Reply:It's old cast iron (baseboard).  It's disassembled and sitting in the barn, so I can safely get at it with a torch.
Reply:Not sure if you can do it with cast cuz the color difference isnt the same but with steel you can heat right beside a crack, and, because of the crack, one side will get red and 'tother side wont. Cast will be a bit tougher. Not sure I would want to heat cast like that. If the part is small enough to go in a bucket, soak it in diesel overnight. Then, wipe clean with a dry rag and sprinkle some flour on it. It'll show---
Reply:Is there an aircraft mechanic shop otherwise know as an FBO in your area they'll have a dye penetrent kit. Many automotive machine shops will have it also.
Reply:Use an ultraviolet-activated liquid and a black light. You can thin out any fluorescent paint then brush it on then wipe it off and hit with a black light. You can also use UV dye made for leak finding in automotive systems.
Reply:I get mine here; http://www1.mscdirect.com/CGI/NNPDFF...0&PMT4TP=*LTIPAnything worth doing is worth doing RIGHT
Reply:Thanks to all for the good advice, bet they all will work.  I'm going to start with AT fluid and cornstarch, as I happen to have both at hand.