I've been a watchin' ................
Maybe I can help you out with this bloomin' project..
You obviously have the ability; all you need is a method that is simple. Now at this stage what do you have to lose..... you can learn from this. Besides, you have too much invested here to just quit.
I really think you've been trying to juggle too many nuts at one time.
just another 15 minutes with the Simple Green....... you CAN save this.
1. Get your original color re-established. I suggest using acrylics - forget the modulation; if you're going to do whitewash, it won't matter anyway.
A. Forget the hairspray.
B. Lose the Future.
You won't need either one on this project.
2. Now get some Grumbacher's Academy White oil paint and turpenoid thinner (in the 
BLUE can, NOT THE 
GREEN ONE!) from Hobby Lobby or wherever.
3. 
After repainting the initial color, give it a day....... relax, this isn't gonna be difficult.
4. Now, squish out a blob
of oil paint about one fourth the size of a computer key (not the space bar) on a piece of raw card board. Let it set for about 5 minutes, you won't be using all of it........ I hope.
5. Put your thinner in a drink cap lid and set it right beside your paint on that piece of cardboard. Lay out a range of small paint brushes and napkins and some crumpled toilet paper within easy reach.
Now, don't be scared..... at this point, you don't have anything to lose. Patience is required here but the results are truly gratifying.
Okay. Take a breath and try the bottom of the hull first. Yes, I know they didn't whitewash the bottom but this will give you a feel for what you will need to do with the rest of the project.
6. Take a ¼ inch brush and cover the bottom with turpenoid....slop it on ......... good-n-wet.
7. While it's still wet use another brush and lightly jab the titanium white in a spread pattern leaving spaces about the size of a dime...... there's plenty of time to work this so don't worry about that. Crumple up the toilet paper and use it to lightly jab and dab up some of the whitewash. You're wanting to get a random based pattern started here. This is the first of several layers so it doesn't have to be heavy. The wetness will make it look dark but when it dries tomorrow the gray base coat will appear slightly more faded, which is what you want. Get it the way you think it looks right and set it aside until tomorrow....... patience............
8. Ok, so it's tomorrow. Unless you just really try hard, you'll be able to add a heavier application today without budging yesterday's result. This will be more in the form of a wash....apply it in the same manner. Give it another day.....a bit more faded now ....... hey, it's a hobby and that's what it's supposed to do....you do it in your spare time.
You'll like that dead flat finish you're getting; that's what the cardboard does.
9. Since nobody should be looking under here ,
give it a try with some streaks by putting a toothpick dallop of white on yesterdays finish. Now dip a small brush in the thinner and just pat it lightly on a napkin twice and carefully/gently drag it down one side of the dot. Might have to do it a few times but if it gets crooked just redampen the brush in the same manner and go down the other side of the dot to straighten it up. You'll need this experience on the upper surfaces. After steak practice .....yeah, take another day....think about what you've done.
10. Alright now; time to drybrush. Go back to your acrylic base color and well, drybrush it on. When it looks just a bit "TOO" overdone, it should be about right. Give it about 20 minutes to dry, gotta love those acrylics.
By now you should feel more confident in what you're doing and the next step will begin to show the rewards. Back to the oil paint now.
11. 
You're on the bottom of this tank to learn so here we go again. You can do this two ways, take your choice. On a wet surface....place a more widely spaced pattern of white and thin/blend it out quite a lot using the brush and/or the crumpled toilet paper as a blotter. On a dry surface add thinner a bit at a time and distribute accordingly. The purpose is to gently fade the drybrushing giving the desired illusion of worn whitewash. Remember that you WANT the whitewash to stay in the cracks and crevices because that's how it would go in he real world.
While it's wet you can do a lot ..... but the next day it's there to stay.
You should be getting a feel for it by now so you may have to go back and forth between # 10 and 11 a few times to get it the way you want it to look.
Trust me though, if you play with this, it WILL work out very nicely...... no dullcote needed either. Always give the thinned oils a day to dry and you, time to think.
Well, I think I covered it all..... Here goes.
