when working with smbc?

i don't know exactly what you mean

yellow blotchy butter then the next sentence says it's not in the icing and it turns out great so i got lost--sorry

you mean it's goes blotchy after it's all smoothed out???

if yes then that might be some cooked egg whites

does the boiling water touch the bottom of your double boiler/bain marie?

there should be a distance between the boiling water and the egg white pan

and are you stirring the meringue constantly from the bottom all over while it is cooking???

also-- is your butter room temperature soft when you put it into the completely cooled off meringue?

sounds like you might be melting part of it as you go

and

hey--

ice your cake--use a wide flat blade to smooth it as best as possible

hold the blade, turn the turntable--viola

chill it thoroughly

use your pristine finger/palm to further smooth out the stray marks & fashion a beautiful top edge

using a turntable again of course

http://www.samsclub.com/sams/stainless-steel-dough-scraper-6/103056.ip?refcd=GL05251200010037&pid=_CSE_Google_PLA_Power-Equipment,-Tools-&-Auto&ci_src=17588969&ci_sku=159689S

It sounds like your butter melted too much.  Make sure that your meringue is completely cooled before adding the butter, I sometimes hold bags of ice around the bowl, while whipping, to help speed up the process.  Also make sure your butter is soft, but not melted.  Never put the butter in the microwave to soften.

This is what I have found since I have encountered my fair share of blotchy smbc:

I smooth it just after putting it on the cake - never after having been refrigerated.  I tried the hot spatula method and it resulted in horrible blotches so I thought that if I just scraped it with a room temp scraper, it should be fine - nope.  Blotchy streaky yuckiness.

What happens is that your cold butter comes into contact with something warmer (the room temp scraper) and melts, thus creating the streaks.  Pure and simple.

I've read that other people can smooth a cold cake and not affect the color, but It cannot be touched after refrigeration, in my experience.  The only time I do smooth it cold is to get it super smooth for fondant (when it won't show the streaks).