By far, the question I get asked the most about glaze icing......

"What causes those awful white spots on my icing when it dries?"

I suspected that it was temperature related, but I'd never actually tested my theory.

Until now......

Since I'm asked about this phenomenon at least once a week.....

it was time that I did a little experiment to see if I could pinpoint the problem.

Now....I'm not a chemist.

Oh sure.....my job title at my real job is Clinical Laboratory Scientist.

I do the testing in a hospital laboratory....and I minored in Chemistry a LONG time ago.....

but I can safely say that I don't remember most Chemistry. haha

So my experiment is certainly not truly scientific.

I went the practical route.

Since I've experienced white spots on my cookies more in the winter,

I suspected that it was due to the cooler temperatures in some way.

The house is cooler in the winter than in the summer.

And since I don't put my cookies in a special climate-controlled room when I dry them....

that probably means that the temperature matters in regard to splotches.

So.....I made five different rectangle cookies and flooded them with glaze.

I picked dark blue for the color since that seems to be one that shows spots more frequently.

As soon as I flooded them, I place them in their "drying areas".

The first two cookies were dried at room temperature......kind of my "control" cookies.

We set our thermostat at 68 degrees in the winter.

I suspect that it is actually a little cooler at our kitchen table since it is in a great room

and right next to a sliding glass door to the outside.

One of the two cookies was just flooded....period.

The other one was flooded and then dried slightly with a heat gun.

(My normal routine is to lightly dry my cookies with a heat gun.

You can read about it more here in this post.)

Oh.....and I use a floor fan to dry my cookies the first few hours after I decorate them.

(Can you find the blue rectangle cookies?
Instead of "Where's Waldo?".... where's the blue cookies? haha)

I placed the third cookie outside in the garage (partially covered, of course).

The temperature that night was about 30 degrees F.

The fourth cookie went into the refrigerator.....which is in the range of 2 - 6 degrees F.

And finally, I put the last cookie in our chest freezer.

I'm not exactly sure what the temp is in there.....but it is COLD and frozen. ;)

Note: The only cookie I covered was the cookie sitting out in the garage.

And I only partially covered it.

The rest of the cookies were open to the air in their environment.

I let the cookies dry overnight.

The results were as expected......except for one rather incredible surprise.

I did my best to take photos to give you a clear view of what the dried glaze looked like.

But it is really hard to show tiny white blotches.....

However, I do think you can see the difference in these photos....be it ever so slight.

It was not a surprise to find lots of little blotches on both the refrigerated cookie

and the cookie set out in the cold 30 degree temps.

(You have to look really close to see the white spots, but they are there.)

The big surprise was the cookie placed in the freezer.
Notice it is the cookie on the far left.
It turned out darker and amazingly more shiny than all the rest.
And there was not a single white spot/blotch on it at all.
It looked as good as the room temp cookie using the heat gun.
AMAZING!

Now I'm not necessarily recommending that you can
freeze your decorated cookies ahead for any length of time.
I tried this once.....freezing the already decorated cookies for more than a week.
And they ended up having blotches all over them. :(
Here's the blog post I wrote about it.

But maybe "flash freezing" the wet glaze is an option.
I'll have to do more research and freeze them for different lengths of time.

What I would suggest if you are having lots of problems with white spots/blotches....
make sure you dry your cookies in a warmer room temperature.
In the winter.....maybe put them in a room with a space heater.
In the summer.....with air conditioning, make sure your cookies are not close to the AC vent, etc.

OK.....I'm now going to take my "scientist" hat off.....and replace it with my cookie decorator hat.

:)

Freezing Glaze Decorated Cookies?
Heat Gun
Heat Gun II