Amanda Camp

When a local boutique closes its doors, it’s usually seen as a sad circumstance. But when it’s because the boutique’s owner needs to concentrate on an increasingly successful apparel brand, it’s far less gloomy. Such is the case for Celeste Sipes, who will close her 10-year-old shop Radish Underground to run Thunderpants USA (TPUSA).

Originally from New Zealand, Thunderpants is an underwear line sold by Sipes during her shop’s early days, and later licensed for manufacture in the US. We chatted with Sipes about this growing apparel company and what the future has in store.


MERCURY: Other than the growing trend toward shopping online and competition from big corporations, were there any other factors that precipitated this move from Radish Underground to Thunderpants?

CELESTE SIPES: There were three other major factors, and the first is a matter of simple economics: decreased overhead and increased control of pricing and costs. The second was the momentum of the two companies. Radish grew every year from 2008-15 and then started to dip in the fall of 2016. No matter how much energy I poured in, it just felt like it wasn’t having an effect. Plus, at 10 years we needed an upgrade and I was feeling pretty tapped out. TPUSA, however, was growing on its own and was taking much less effort on my part. The third is the constant battle between work and quality of life. Thunderpants has offices in St. Johns down the street from my house—less waste and no commute. I have an amazing employee who handles much of the daily running of TPUSA, so what I mostly do now is production management.

Amanda Camp

How has Thunderpants USA grown since its launch in 2016?

At a steady pace. Our demand is always just nipping at our supply, which has been very fortunate. Thunderpants are so high quality that we get lots of returning customers who spread the word... so we’ve been growing through word of mouth alone. We haven’t really pushed growth yet, because we had to focus on getting our entire US supply chain up and running. The minimums for custom knit fabric are very high, so I had to get that timing just right. We ramped up production at the beginning of the year because we were selling out, and I’m doubling again in July when we get our first batch of US-milled fabric. I’m hoping that “not pushing growth” and letting the company grow organically translates into massive sales.


Thunderpants NZ also sells childrenswear, swimwear, yoga pants, and leggings. Are there plans to sell these items in the US?

Yes! We’re launching a bralette and women’s boxer brief in the next couple weeks. We have children’s undies and leggings on deck and will start the process of swimwear later this year for an early 2019 launch. We’re also adding sizes 3X and 4X in most styles, hopefully by late summer. We also have our first Portland artist-designed print coming out in July, which I’m really excited about, and I’m in the first stages of working on our first “philanthropants.” We’re going to work with a local charity to design a print inspired by their cause and donate a portion of all sales to them.

Gurusurya Khalsa

Tell us more about the factory that manufactures Thunderpants USA. I’m always excited to hear about local clothing companies that use local factories.

The single most important factor in this whole process was finding Evergreen Apparel Manufacturing. They normally work with bigger athletic companies and don’t have time for small runs. They took a chance on us because we had the potential to be a really good fit—we produce monthly and our patterns don’t change season to season. They were flexible, but also very clear that we needed to get our numbers up to a pretty high monthly minimum to keep our place in their production schedule. That turned out to be good motivating pressure for us. Beyond the fact that the quality is amazing, it’s a delightful place. Manufacturing practices are a big deal for me. Now I get to stand in the factory and work with an owner who cares about the same things I do... especially quality. I’ve seen the hardships of production, so I know exactly how lucky we got!

More info at thunderpantsusa.com. Radish Underground (414 SW 10th) closes for good on Sun June 17.