Hi Cal,
Happy to jump in here with some sound basic advice. Reading your post, i got the impression that the car you own now and the present color it is, will be short lived as you intend to get serious and upgrade the whole paint work with a respray and color change back to Ivy Glow Metallic. I assume that the Ivy Glow was the original factory color used, and you will be doing a strip to bare metal repaint on the whole car.
That said, it would be fair enough to say that whatever touch ups you want to carry out on your car now, would be just a quick, no fuss get out of jail remedy to make the car presentable in street appearance wise. As you said you don't want to drive a primer bucket around again. If you go ahead and carry out the touch ups you want to, what would be your approach? Would you be doing the spray work yourself, or be taking it to a paint shop to have the work done?
If you intend to do the spray work yourself, will you be going down the rattle can path, or using spray guns with tins of auto paint and a compressor? What ever way you choose to go, here are some basic key points to bare in mind regards obtaining a good color match now.
You state you believe the color on the car now is called Medium Blue Metallic, but the reality is you can't be really certain. If you had in your possession now, a paint tin of left over auto color that was used to paint the car, and it was labelled with a color name and code, then that would bring the proper evidence to verify the actual color used by the previous owner. You could then use that as an accurate guide to make up more color of the same. Your paint and panel shop would take care of that.
Lets look at the key points. Auto color identification always comes with a color name and a code. All auto colors are made to a color formula involving several tinter colors added together in varying quantities to reach the final factory color. However, in the auto refinish world, any factory color name and code, is never a guarantee that when that color is made up or reproduced to the stated formula, will be an accurate color match on your car. So if you're buying a rattle can of color or a made up tin of auto color made to a factory name and code, it will not be a spot on color match.
There are three ways to achieve a (CLOSE) color match.
1. Making a color up from scratch by eye (no formula), and finally accurately color matching it by eye with your qualified auto spray painter.
2. Making a color up from a code and formula, then getting your auto spray painter or auto paint supplier to finish off the final accurate match to your car. (best to use the services of a qualified auto spray painter over the paint supplier, as he will deliver the most accurate result. If you are buying the paint using the rattle can approach, most auto paint suppliers, don't have the qualified staff to carry out pro color matching as such).
3. Using a Spectrophotometer, making the color from scratch as per the spectro's recommended formula. Spectro's are around 91% accurate, and the final made up color may have to be finished off by custom eye matching to the car, by a pro spray painter. Going the spectro path, will get you involved with your paint and panel shop mainly. Auto paint suppliers have not gotten involved much with using spectros, as they cost thousands of dollars, and takes considerable time to match the made up paint to your car. They are in the business of selling auto paints, not color matching them.
It's important to know that in all three cases above, your car will have to be present to get the best accurate match, and also will have to be carried out in direct sunlight, being a fine sunny day. Several spray test cards will have to be sprayed out and used to end up with the best possible match. Also, all metallics with have to be back blended into surrounding panels for accurate results. Trying to spray out panel to panel brings bad results color matching wise.
On the other hand, if you are looking for a fast, cheap, no fuss way of getting out of jail with your touch ups, then taking the approach of near enough is good enough with your color matching may well suit you, as accurate color matching can be fairly time consuming and expensive if done properly.
To finish up, i will quote an example of color matching my original factory painted Gold Glow Metallic for my '73 vert respray. I started out with a factory color code, and made up the color on my spray shop scales as per the recommended formula. It came off the scales not being a good match. That then meant that i had to eye match it for a finished accurate result. Gold Glow is a very, very hard color to match in any regard, and i ended up spending around five hours of trial and error spraying card spray outs, getting it as close as i possibly could with a good looking three way flip. Accurate color matching is a learned skill and an art, involving many years of practice, and can't be done properly by watching a few U Tube videos. We are thought to work with around 30 plus different colored tinters.
Hope that all helps,
Greg. (Pro auto Painter)