Hair coloring/correction - anyone hear of a soap cap?

I've decided to take the plunge and let my hair grow out gray.

As an aside, one aspect of this is seriously traumatic for me. I have no problem going through the color correction process. It's the realizing I have absolutely NO idea what my hair really looks like, who I would be/look like. My hair hasn't been uncolored for at least 20 years. It's a bit of a mini identity crisis to be honest.

I've seen on the interweb pictures of young women who have made their hair gray on purpose. While mileage may vary, some looking awful, some of them actually looked really good. I thought if I could get someone to do this, it would be over in one fell swoop.

Anyway, went to this fancy schmancy expensive salon to get advice, and they gave me a free consultation (nice, they didn't have to do that) While I was waiting, I saw a young woman (mid twenties) who worked there who who had her hair done an Amaizing gray. I asked her what her natural color was, and she said "brunette" which gave me a lot of hope. I told her I hoped I talked to the person who did hers and she said, "Yes you will, here he is...."

So he explained the process which is essentially striping your hair, making it a light ash blonde I supposed, so the gray growing out less dramatic from the dark color it is now. He said (as I already knew) "red is the hardest to get in, and the hardest to get out. It would be unrealistic to tell you your hair would like like Lindseys (the young womans) but in the 4 hours I'd work on you it would probably get like that womans over there." He pointed out a customer across the way who had what I think of as a dingy, none descript type of blondish thing going on. I really don't like blond hair to be honest.....Nothing to do with the person who has it, I just could never get behind having that color, unless in the most temporary situations, like this. I don't have the coloring for blond hair at all, IMO. After the stripping, I'd have to have a good bit of the hair cut off....not just because of the damage to that hair, but of course to get that unwanted blondish stuff out of the way.

My hair wouldn't be like Lindseys, because (a) it's red, not brown and (b) working there, I'm sure he was able to do her several times to get it to the stage she was at.

I thanked him, and driving home wondered if over the next couple/three months I could somehow provide him, or someone else, a less red palate to work with, like instead of coloring my hair red, I could go lighter and lighter brown. I know that when coloring hair a darker color, you're just depositing color. Depositing on top of the red. But I figured if I started doing the roots brown, and started cutting off the red hair as I went along, I could end up w/ brown.....but how to do this without looking like a People of Walmart special?

I went to Sallys to get some supplies, and ask someone there who knew something....

I talked to someone there who really seemed to know her business, but wanted to see if anyone here has had experience with this "soap cap" thing.

The color I'm at right now is 4R, R for red. She said, since it's time for a coloring (2 weeks, yes, I now have to color every 2 weeks to keep up with used to be down every 6....then 4, then 3 weeks....ergo I'm tired of this and give up) to go up to the next level lighter....a 5N, N for natural brown. She also said to buy this additive to put in the solution called "UNRED" I've looked at online and it get's overall good reviews.

She said to add the UNRED to the die mixture and apply as usual to my roots as far as timing (35 minutues). Then, to the remaining mixture add an equal amount of shampoo, and apply this soap cap to the rest of the hair for the maining time (another 10 or so) Something about that the shampoo would act as a buffer, and keep too much of it from getting into the hair shaft. With the REDOUT taking out red, and the buffered brown going in, it made sense to me then.

However, looking up soap cap online, almost all the information/examples of usage applied to using it to buffer the bleaching/stripping process, adding it to a bleaching agent, not color.

I'm going to cut off a lock of my hair from the back to see what this does, but figured someone here would know something about it.

I know this is long, but hair correction isn't simple. It's not at all cheap to have a professional do this either.