I have been using this buttercream icing recipe for a while now, and its held up well so far.So.....im in the car, right. with the air on FULL BLAST and the icing was getting a little droopy. by the time i got the cake from the parking lot on to the table in the resturaunt the wall of icing on the cake was basicly sliding off like fondant!!!. . now im new with cake decorating and stuff, but how can buttercream icing melt in a car thats near 60 degrees(exagerated maybe 65-72) . it was about 83 deg outside but i wasnt outside for longer than 1-2 mins. the cake was my for my grandma so she loved it anyway.(only the decoration on the top was left )(more exageration. there was still icing on the sides.srry im very dramatic ). someone plz explain why the cake gods shamed me that day lol.

What is your buttercream recipe?

Between the butter, cream, and corn syrup, was it a very soft icing? Maybe that was the issue?

doesn't sounds like enough PS to me! i've never put corn syrup in my frosting unless i wanted to thin it out for writing.

I use sugarshack's recipe and it holds in severe heat and humidity, never have had any issues with it ever. You may want to check it out!

It will also be more stable if you use more shortening, and less butter. I use equal parts butter and shortening. I also don't put in the corn syrup.

Sounds like too much butter and a very soft Icing. Might be tasty but not strong enough for heat.
Edna

Could the sun have been shining through your car windows directly onto the cake?? The sun gets very hot shining through glass windows. I had that happen to a birthday cake I made for my dad. The icing slid right off the side of the cake. Now I always make sure that my cakes are well shaded from the sun when I am transporting them.

no matter what if your cake gets to a certain temp itll melt, the best thing to do is sacrifice the flavor of real butter use a crusting buttercream with just shortening, look for a buttercream that does have transfats, or a high ratio, or as i think i learned from edna-add a touch of milk or cream to add the fat back in. your ratio of sugar and shortenting must always be at least 2 parts of sugar and 1 part shortening. if you look up crusting buttercream or the viva method recipe in the search on here then that has proven to be a sturdy recipe for me, and i live in houston tx where the sun and humitdity literally make the outdoors a suana dripping beads of sweat with in the minute of being outside! :/ i love butter in my buttercream but that is a personal indoor cake only sort of thing now. and i got my first recipe from my culinary book!

I live in Hot, HUMID, Texas....and I had a problem with this until I started to use INDYS RECIPE...I can do a wedding tier cake and transport it, let it sit in a hot room or even outside for abit...and holds in temp of 98

Its on here on CC

I'm echoing what others have said. I question the recipe, sounds like a creamy frosting rather than one that stands up to much heat at all. Did your piping look 'crisp' as you were doing it or did it seem to relax a bit?

When I transport, regardless of temp. outside it's in a shady spot in the back. I've got tinted windows and those little shades they have for babies are wonderful as well. If the cake is small enough it's in a covered box shading it more.

So happy it was for your grandma! I'm a pretty new grandma and no matter what my granddaughter did it would be perfect

Our June averaged about 100 degrees per day and about 95% humidity. I was terrifed of buttercream melting but I have a plan for delivery and delivered over 45 minutes away with no problem.

all of my completed cakes go in a box and I refrigerate overnight, even tiered cakes. I keep the box closed and put it straight from the fridge into a car that has the a/c running full blast and has been for at least 15 minutes to keep the car cool. I have an SUV and it sits in the back and the windows are tinted. It stays in the box unti I get it inside the venue. It goes from the box to the table. Even with our superhot and humid summer, I didn't have any melting. Most of the time, I use Sugarshack's buttercream but this worked even for a vanilla rum buttercream that is all butter. I was afraid that it was going to melt inside the venue because it was so hot in there but the bride said it held up great, no melting.

Wi9th Sugarshack's recipe, I never refrigerate a cake. Never. The cake does not have to go through the condensation and temperature changes that way. I have never - not once - had an issue with melting frosting or any of those issues. It holds in 96+ heat with 90+ humidity just fine. I have 6 qt. KA and use sweetex to make it.

2 lb 13 oz. sweetex
1 + 1/4 cups plain liquid creamer
5 Tablespoons flavoring
6 lb. powdered sugar

That recipe makes 6 qts. of icing. (I think I measured out 18 cups)