Seaming something with stripes?

[MmmKnits]

I'm almost done with the second sleeve of my Manly Sweater from S 'n B. It's my first sweater, and it looks like it will actually be done in time for me to give it to my boyfriend for Christmas, so let there be much rejoicing in the hiz-ouse.

But now it's time to embark into new territory, the world of seaming and finishing. I have two questions:

1) Should I seam the body and sleeves according to the stripe pattern? I knit it in the suggested color scheme (a gray body with a wide red stripe across the middle bordered by two small black stripes).I could see using the gray yarn to seam the gray and even the black portions of the sweater. But what about the big red stripe in the middle? Should I tie off the gray securely and switch to red for that part?

2) Should I seam before or after blocking the sweater? What works best in your experience? I guess I swatched rather haphazardly and knit too tightly, so I'm hoping to stretch out the final product a bit. Would that make a difference in your answer?

I can't believe I made it this far. And now I'm almost done! Please share your wisdom with me, so that my final product doesn't end up looking too amateurish. I'd really like to impress my boyfriend (and about 20 of his Danish relatives, whom I've never met before) when he opens that box on Christmas morning...

Thanks!

[8ball]

If you use the mattress stitch (I think that is the one you use), the seam yarn should be invisible.

Also, block b/f you seam, not after.

HTH

Carie

[lynnsch]

Definately use the mattress seam...it's practically invisible, and if you do it right, your stripes will line up perfectly.  If you need directions, the best that I found were in the back of a Creative Knitting magazine.  It's not very hard to do, but I will warn you that the first time I did it I had to tear it out and start over to get everything to line up.  Good luck!

[MmmKnits]

Thanks for your responses! I was planning to use the mattress stitch to seam--I just wasn't sure if any of the seaming yarn would show up along the sides of the garment. Sounds like it won't (and I guess if it does, that means I'm doing something wrong and should start over). As for the blocking, my natural inclination was to block first/seam later, too, but grew indecisive after reading that line in S 'n B where the author said something about how nobody she knows does it in that order... Well, you all have set me straight! Thanks again.