Little Flash rust issue

C

cstrom72

I had this 67 Mustang shell sand blasted and the only way I was going to be able to get the sand out of every nook and cranny was to power wash it. Now literally by the time I was done the driver side rear quarter had a lot of tiny rust spots. They are very small and they don't come off very easy- there are a few other small spots around the car of course as well.

Here's my question- I started with some W/G remover on a red scotch brite pad to remove the flash rust. and its really hard to do- and it leaves the finish not as "rough" as the rest of the sand blasted parts. Am I going to have adhesion issues? I really don't want to go over the whole car with a DA and 80 grit- that would kind of defeat the purpose of having it sandblasted that we paid a grand for haha-

Thanks



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I avoid cleaning large areas like that with water for just that reason, a vacume with a few attachments and an airgun usually gets the job done. I'd scotchbrite it and DA sand it for texture but now that it's growing you're going to have to get on it asap. Do a few panels at a time if it will take too long to prep the whole thing for one spray session or get some help to get it done. I know Shine and others may primer over flash rust all the time without problems but I avoid it.
 
Bob Hollinshead;40511 said:
I avoid cleaning large areas like that with water for just that reason, a vacume with a few attachments and an airgun usually gets the job done. I'd scotchbrite it and DA sand it for texture but now that it's growing you're going to have to get on it asap. Do a few panels at a time if it will take too long to prep the whole thing for one spray session or get some help to get it done. I know Shine and others may primer over flash rust all the time without problems but I avoid it.
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I get what your saying. I spent about 3 hours with a shop vac and air and rags and it was getting me no where. Lesson learned not to have it dustless blasted. They use a fine mist of water with it and the sand clumps in places and sticks to everything. I knew if I didn't get it all out it would eventually find its way onto everything as the car bounces down the road. Would I really have to DA it after just scotchbriting the problem areas?
 
Boy I wish they all looked that good when done blasting. Not even a dent on that quarter. Wow.
 
cstrom72;40512 said:
I get what your saying. I spent about 3 hours with a shop vac and air and rags and it was getting me no where. Lesson learned not to have it dustless blasted. They use a fine mist of water with it and the sand clumps in places and sticks to everything. I knew if I didn't get it all out it would eventually find its way onto everything as the car bounces down the road. Would I really have to DA it after just scotchbriting the problem areas?
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If it's textured good no need for the DA, any idea what sized grit was used when they blasted it?
 
I would think an 80 grit da would make quick work of those spots. Just to learn from this... what was the time frame from the dustless blasting to these pics? The same day or the next day?
 
if they used sand then the rust is happening because of the caustic salts in it. i wash with dawn soap after blasting and will get a little orange flash but it is no big deal. easy to get rid of. this tells you it is clean . big compressors have an oil separator on them. they will blow some oil vapors. i have never been able to remove all the media without washing. as soon as it's rinsed i bring it in and blow dry and epoxy.
 
I dont know about the caustic salts, anything keeping the metal above neutral ph is what keeps it from flash rusting. Pretty sure that is the whole reason for adding dawn (or any dish soap) to the water when you are washing it down. The phosphates in the soap are keeping the metal from flash rusting.

You can get a little suction blaster you use with a bucket and a 50# bag of blast from menards for about 30 bucks total. If you can take it outside I would take it outside and blast the flash rust, keep your profile, wash it with soap and prime as soon as possible.
 
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