Quick, cheap, temporary rust protection options

So I'm hoping to send the DMC's badly rusted frame off to be blasted once the garage is finally cleared out of all of the stuff for The Dancer's non-profit's fundraiser yard sale next weekend- but it's going to be at least a modest while before I will be ready to do the final, 'permanent' (as much as that's possible) rust protection coating on it. However, I know that it will start to rust again pretty much as soon as they're done blasting it so I want to try and figure out a way to keep the rust to a minimum while still being easy to remove to a) make the repairs necessary (welding on replacement metal) and b) put the final rust protection coating on it (at the moment, I'm leaning toward the POR-15 option since I would be able to apply it inside of some of the areas that will be somewhat enclosed once the repairs are made).

Are there any quick, cheap solutions that anyone knows of (and ideally has some experience with using) that I can use to quickly coat the bare metal that can be easily removed (or, I suppose, I can either just weld through or apply the POR-15 on top of)? Thanks!

I've been using phosphoric acid to parkerize my exocet frame. You can just paint it on at full strength and then wipe it down with mineral oil or WD40 or equivalent to stop the reaction and remove acid residue.

I can't believe how durable the result is. My frame isn't rusting and I've just been ignoring it. I'm just going to clean with mineral spirits and paint it whenever the weather dries up properly, but until then it looks beautiful. 

It still looks like this. I'm not sure what will cause it to rust, now. 

You can get phosphoric acid by the gallon at home depot, it's about $19, sold as 'concrete and metal prep'. It's absolute magic and I'll never be without it again. 

I painted some of the underside of the ES miata with it yesterday. 

I can't believe they put this stuff in soft drinks. 

In reply to dr_strangeland :

That must be how I've managed to survive this long. I'm tempered in Coca-Cola.

In reply to dr_strangeland :

So,

1. Brush on Phosphoric Acid
2. Wash off with Mineral Oil
3. Paint/Weld over at will?

If so, that sounds like pretty much exactly what I want. I'm hoping to make the basic repairs to the frame pretty quickly, but there may be a few things I do down the line if I need to modify the frame to fit the new motor/batteries which I don't have yet.

Yes, that's the same brand I have been using.

You have it exactly right. The container even says that the surface is ready for paint after acid treatment. I think the key is to cover with a film of light oil to keep moisture off, but even so there's a durable layer of iron phosphate that doesn't appear to rust. If you leave the acid on at full strength and don't wipe the excess off at all, it will continue to act on the metal and makes some kind of orange colored residue that's very hard and not exactly rust, I think it's iron phosphate but orange instead of black. I don't recommend this, it's hard to remove. Just clean the excess acid off thoroughly with shop towels once it's done working on the rust, spray with mineral oil, and wipe again or just let it run off. A couple hours of contact time for the acid is plenty at full strength, maybe even less depending on how much rust there is.

I used green scotchbrite pads to remove surface corrosion and get that lovely finish.

 When you using these coatings , how does it react when you want to put the finish paint on it
just wondering if it will weep thru 

https://en.wikipedia.org/wiki/Phosphate_conversion_coating#Painting_primer

I think iron phosphate doesn't really react with much. To be clear, this isn't a coating as such, the phosporic acid reacts with the iron oxide to turn it into iron phosphate. If anything the acid cleans/etches the metal completely, so any kind of coating (in my case there was a bunch of mill scale on the frame) will come off. Just bear that in mind. 

NNKH swears by this stuff. His field use and YouTube updates indicate it works.