If she wins this bet, she'll get to appear on television on the PBS program, "Antiques Roadshow."
But even more important to Hemm than the TV spot, she hopes that two precious dress patterns -- dating back to the 1880s -- that she has protected for the last 25 years will finally be appraised.
It's not that she wants to cash them in for the money. Hemm wants to know the value of these two patterns, which have never been opened, to help her decide where to donate them.
"I don't want them in the Smithsonian where they will lie in a drawer," Hemm said. "I really want them to be treasured for what they are -- a piece of fashion history at an incredibly detailed level, which is totally lost these days."
Before we get to Hemm's "costume" and "Antiques Roadshow," let's go back about 25 years.
In 1987, Hemm's uncle, an antiques dealer, was in Pennsylvania at an outdoor auction when he came upon two dress patterns. They were "dead stock" patterns, never opened, never used, from 1880 and 1881.
"He grabbed these thinking, 'Joan will make these,' but they are actually well beyond my sewing skill level," Hemm said.
Hemm is a historical costumer and has been sewing costumes since high school. Hemm also started a women's history group in Colorado when she lived there and now belongs to the Seattle historical costumer group, Somewhere in Time, Unlimited.
As an appreciator of historical things and the importance of preserving them, Hemm "couldn't think of cutting up patterns that are 130 years old." So her uncle's gift went into storage.
Fast forward to 2004.
Hemm and her husband had left Colorado and moved to Mukilteo. While settling into her new home, Hemm uncovered the two dress patterns. That rekindled her desire to find the right spot for them.
"My plan is to give them to either the Fashion Institute in L.A. or New York, where they can be studied and preserved, but first, I'd really like to know what they are worth," Hemm said. "What if they are the only ones in existence?"
She started to investigate on her own but got nowhere.
Hemm figured she'd have to be on "Antiques Roadshow" to get an answer.
So she tried to get tickets. Just 2,000 tickets are allotted for each location of the "Roadshow's" filming. For five years, she tried to get one.
When the show announced it would be in Seattle, she had a friend of hers sign up for the ticket lottery. That friend's uncle is on the show. Hemm finally got her tickets.
Hemm then thought about how she could help guarantee an appraisal.
She recalled from her costumemaking days how much attention a costume can draw.
"I remembered the absolutely amazing effect a costume can have," Hemm said. "People approach someone in costume with curiosity and interest and they are very appreciative of their efforts."
Hemm and a friend from Denver have sewn replicas of these 1880s-era dresses -- without opening the patterns -- to wear to the "Antiques Roadshow" event with the hope of generating enough interest in the patterns to get on air, and an appraisal.
Like getting on the Jumbotron at a ballgame, you've got to create a bit of a spectacle for the cameras to notice.
"Making this gown is one in a number of steps on my journey to get on 'Roadshow' and find a good home for these patterns," Hemm said. "I was thinking, 'What's my best chance?'
"I have got to make things happen."
Hemm's dress is a "reception gown" she made from a comforter cover in a dark red and tan. Reception gowns were worn back in the day when women were at home to greet guests.
Hemm's girlfriend is making a walking suit, what a woman would wear to go shopping. Her outfit has a matching hat and bag. Hemm's has 15 buttons down the front, a train that drags and a huge velvet bow in the back.
Hemm's dress plus corset weighs 8 to 10 pounds. The two friends are going to bring little folding chairs with round seats to sit on during the show.
"Antiques Roadshow" is scheduled to be in Seattle on Saturday. On Sunday, Hemm and her girlfriend are scheduled to make a presentation at the Everett Public Library to talk about their experience at the "Roadshow" and show off their vintage creations.
Hemm is hoping they have good news to share.
"It's to share (our experience) with other people. It's too much fun not to," said Hemm, who said she has felt like a steward of these patterns all these years.
"I made this discovery and, by God, it's time to do something with these," Hemm said. "Give them away and let them have another life."
The 2012 six-city tour of "Antiques Roadshow" makes a final stop in Seattle for an appraisal event Saturday at the Washington State Convention Center, 800 Convention Place, Seattle. About 6,000 guests are expected, bringing about 10,000 items to be viewed by more than 70 appraisers for possible inclusion in three episodes to air sometime between January and May as part of Season 17.
Joan Hemm's presentation
The dresses will be worn during a free presentation and talk by Joan Hemm from 2:15 to 4:15 p.m.* Sunday at the Everett Public Library, 2702 Hoyt Ave., Everett. Tea will be served.
*Correction, August 15, 2012: This story originally gave an incorrect time for Joan Hemm's presentation at the library. Doors open at 1:30, tea will be served at 2 p.m. and the talk will run from 2:15 to 4:15.
More Life Headlines
Our to-do list full of ideas for your weekend
Our new comment system is not supported in IE 7. Please upgrade your browser here.