My hair is a really nice golden blond color and it's in really good condition, especially considering it's colored, long and curly.

I'd like to go dark but only for a short while, as I really love the color I have and have gone through A lot to get it this way. If I use a temporary dye, will it really wash out? If so, how long does in take to go away?

I saw this product at my local hair place called Jazzing and it looked promising but I'm not sure if I should use it: Clairol Professional - Jazzing - Jazzing Sheer Haircolor

Has any one used it?

I'd really like an expert's opinion on this but any help would be greatly appreciated.

I used that product when my hair was a light blond. The color didn't come out or even fade until I grew my hair out, but I also used Black!

There are several types of "temporary' colors. Those that wash out in one shampoo are usually considered to be truly temporary. Examples of this are the Roux fanci-ful rinse series. Semi-permanent or demi-permanent colors can be permanent on some color-treated hair, especially bleached hair.

My suggestion would be to go to a salon and have a darker semi- permanent color weaved into you hair. Considering that you hair is chemically processed and very light, it won't hold the color for long , as long as you don't go too dark. You may still have a hint of the semi in your hair after it fades, but nothing like you would if you did it all over and used permanent color.

They fade out but I doubt they'd fade to your nice colour you have atm especially as your blonde hair atm isn't natural.

If you use the right one it should wash out. But I'm telling you right now don't use a product called Goldwell Colorance. I used it on my non-chemically treated hair and it hasn't washed out yet. It's been about 4 months since I've dyed it.
If you have applied that much chemical in your hair though, anything you use may not wash out. The more chemicals you put in your hair the more sponge-like it becomes therefore soaking up even temporary colours.

p.s my mom is a hairdresser.

Roux Fanci-ful does NOT wash out of the hair! I am growing my hair out to white and I used this Fanci-ful to make the process easier and now I CANNOT get it OUT of my hair. Any suggestions?

The reason it probably stayed in some peoples hair is first of all SOME temporary hair colors turn into semi-temporary when heat is applied after an application. If u want it to remain temporary you CAN NOT apply heat to the hair right after you color it. And also everyone's hair absorbs color differently so someone may have to wash their hair 4-6 times and the color will begin to fade and some may have to wash their hair 6-8 times before it fades, it all depends on the hair's porosity.