To Wash, or Not To Wash, that is the question...(and then-some)

[SweetHina]

I'm doing a SIP (SIP - Special Inspiration Project) double knit scarf that's B&W (Black & White) [indvidual yarn].

I wonder - before I start, should I wash the yarn before I knit so that when I need to wash the scarf later the black won't bleed into the white.

OR

Should I just knit and wash after finish.

I just bought B&W yarn, they're the Red Heart brand, both Medium 4, 100% Acrylic.

I used the same brand trying to do a different SIP also doing double knit that I saw from the video, with S8 (Size 8) needles. However upon finishing one pattern, the didn't look like how I saw in the video. The sides with the knit loop seem so loose (or is it like that when it comes to double knit), it didn't look nice at all . Even-more-so there's like lose knit loops here-&-there in parts of it . So I bought S6 (Size 6) needles for the B&W SIP.

My questions are:
Should I wash (now) or not wash (now)
Use S6 or S8 for the B&W SIP scarf

Any tips to prevent loose knit loops.

(Like some [if not most] of the ppl on here, I'm such a perfectionist. My bf says we're OCP [Obsessive Compulsive Perfectionist])

[Jan in CA]

I think washing before would be a huge pain. I suggest just making a black and white swatch and washing it to see what happens first. It'll save you a lot of time in the end if it turns out they are fine.

[ArtLady1981]

I totally agree with Jan! Great Idea!

[Debbie]

I don't think acrylic "bleeds", but washing your swatch can never hurt.