Blend mode multiply over a transparent background

[tibberous]

I am trying to turn an icon into a transparent icon. The icon has a shadow layer in grayscale.

I can set the shadow layer to multiply and put a colored layer under it and have the shadow appear properly, but when I try to put it over a transparent background, Photoshop turns the white pixels in the shadow visible.

How can I get it to treat the layer as a black layer with different degrees of transparency?

 

[iDad]

sounds like your reversing the effect by putting layer on top, a visual would help..meaning can you show what you are descibing?

 

[MikeMc]

Turn it black, quick mask and fill ??

 

[ibclare]

I don't think you understand how blend modes operate. They work by blending pixels with the layer below. So screen will add a brightening/lightening effect, emphasizing the brighter levels; multiply will deepen the pixels below. If your layer below is transparent, what are you blending. Nothing.

So maybe we're missing the point. As iDad suggested, show us an image or upload the psd.

 

[guitavares]

I have the same question and I understand what the original question was.
The "multiply" blending actually turns all the whites transparent in a layer.
So if you have a layer with a red circle over a white square (like a japan flag) and if you set it to multiply, then the white square will disappear, showing the contents of layers below.
But what if he wants to hide all layers below and yet keep the white parts on the image transparent? The multiply mode won't work and the white square will show over the transparent background.
Yes, one could use the "select color" tool, but that just doesn't work as nice as the multiply does.
In his case, he has a fading gradient from black to white. When he applies the multiply, that turns into a nice transparent shade. He will not achieve that smooth fading if he tries to select the white parts.
So the final question is: how can we turn an image into a transparent without any background layer (to export and use on a web page, for instance) achieving the same transparency of a multiply blending?