Source Four LED washes

I've seen designers use a frost to help diffuse the lighting.

I think what you are looking for is the Smooth Wash Diffuser as mentioned on page 2 of the spec sheet here:

http://www.etcconnect.com/docs/docs_downloads/datashts/7460L1001_S4_LED_Spec_Sht_vC.pdf

Designed specifically to help smooth out the field with wash applications.

I didn't even see that accessory. Thanks for pointing it out.

Anyone have personal opinions about how well that works?

From ControlBooth - LED Source Four, post#78 :

1) The field, while it may look flat, has a roughly 2:1 falloff. If you blend two beams with hard edges, there will be a bright stripe where the beams overlap. Placing a diffuser (included) in the gobo slot and soft focusing the lens tube improves the blending.

I have used them on a balcony rail position, with the diffuser, with excellent results.

Soft Focus Diffuser (comes with the light with media holder) OR can be installed behind the shutter assembly with an optional magnet kit is mainly for the purpose homogenizing the beam to prevent multicoloured shadows at certain applications.

Smooth Wash Diffuser is an accessory to place in a colour frame in front of the lens tube and is the tool for wash applications.
THis is the diffuser to use for very soft blend or real wash performance. You may be able to create overlaps without it though - try it out........

Erik Larsen
Market Manager
ETC Ltd 

Soft Focus Diffuser (comes with the light with media holder) OR can be installed behind the shutter assembly with an optional magnet kit is mainly for the purpose homogenizing the beam to prevent multicoloured shadows at certain applications.

Smooth Wash Diffuser is an accessory to place in a colour frame in front of the lens tube and is the tool for wash applications.
THis is the diffuser to use for very soft blend or real wash performance. You may be able to create overlaps without it though - try it out........

Erik Larsen
Market Manager
ETC Ltd