Should your startup opt for SAFEs or convertible notes on your next funding round? This Houston expert weighs in. Photo via Getty Images

As both a founder and occasional early-stage investor in the Houston ecosystem, I've seen firsthand the opportunities and challenges surrounding seed funding for local startups. This critical first fundraising round sets the trajectory, but navigating the landscape can be tricky, especially for first time founders who may not be familiar with the lingo.

One key dynamic is choosing the right deal structure — SAFEs (Simple Agreement for Future Equity) vs. convertible notes are the most common vehicles early stage startups use to raise capital and are far more founder-friendly than a priced round.

Let's start first with what the have in common:

  • Both allow you to defer setting a valuation for your company until a later (likely priced) round, which is useful in early stages or pre-revenue companies
  • Both are cheaper and faster to execute than a priced round, which cash-strapped early stage founders like
  • Both can have terms like valuation cap, discount, conversion event, and pro rata rights.
  • Both are less attractive to investors seeking immediate equity (especially important if starting the QSBS clock is part of your investors strategy or if the investor is newer to startup investing)
  • Both can create messy cap tables and the potential for a lot of dilution for the founders (and investors) if they are used for multiple raises (especially with different terms)

While as you can see they have similarities, they have some important differences. Let's dig in on these next:

SAFEs:

  • Created by Y Combinator in 2013, the intent was to create a simplified, founder friendly agreement as an alternative to the convertible note
  • Is an agreement for future equity for the investor at a conversion event (priced round or liquidation event) which converts automatically.
  • It's not a debt instrument and does not accrue interest or have a maturity date.
  • Generally have much lower upfront legal costs and faster to execute

Convertible Notes:

  • A debt agreement that converts to equity at a later date (or conversion event like a priced round)
  • Accrues interest (usually 2 to 8 percent) and has a maturity date by which the note must either be repaid or convert to equity. If you reach your maturity date before raising a qualifying round, you can often renegotiate to extend the maturity date or convert the note, though be prepared to agree to higher interest rates, additional warrants, or more favorable conversion terms.
  • More complex and take longer to finalize due to non-standard terms resulting in higher legal and administrative costs

It's worth reiterating that in both cases, raising multiple rounds can lead to headaches in the form of complex cap tables, lots of dilution, and higher legal expenses to determine conversion terms. If your rounds have different terms on discounts and valuation caps (likely) it can cause confusion around equity and cap table structure, and leave you (the founder) not sure how much equity you will have until the conversion occurs.

In my last startup, our legal counsel — one of the big dogs in this space for what it's worth — strongly advised us to only do one SAFE round to prevent this.

Why do some investors tend to prefer convertible notes?

There are a few reasons why some investors, particularly angel investors from developing startup ecosystems (like Houston), prefer convertible notes to SAFEs.

  • Because they are structured as debt, note holders have a higher priority than equity investors in recovering their investment if the company fails or is liquidated. This means they would get paid after other creditors (like loans or credit cards) but before equity investors, increasing the likelihood of getting some of their money back.
  • The interest terms protect investors if the founder takes a long time to raise a priced funding round. As time passes, interest accumulates, increasing the investor's potential return. This usually results in the investor receiving a larger equity stake when the note converts. However, if the investor chooses to call in the note instead, the accrued interest would increase the amount of money owed, similar to a traditional loan
  • More defined conversion triggers (including a maturity date) gives investors more control and transparency on when and how their investment will convert.
  • Can negotiate more favorable terms than the standard SAFE agreement, including having both a valuation cap and a discount (uncommon on a SAFE, which usually only has one or the other), interest rates, and amendment clauses to protect them from term revisions on earlier investors by future investors (called a cram-down), etc.
We'll go over what the various terms in these agreements are and what to look out for in a future article

How to choose:

  • Consider your startup's stage and valuation certainty — really uncertain or super early? Either of these instruments are preferable to a priced round as you can defer the valuation discussion
  • Assess investor preferences in your network — often the deciding factor if you don't have a lot of leverage; most local angels prefer c-notes because they see them as less risky though SAFEs are becoming more common with investors in tech hubs like Silicon Valley
  • Evaluate your timeline and budget for legal costs — as I mentioned, SAFEs are way less expensive to execute (though still be prepared to spend some cash).
  • Align the vehicle with your specific goals and growth trajectory

There's no one-size-fits-all solution, so it's crucial to weigh these factors carefully.

The meanings of these round terms like "seed" are flexible, and the average seed funding amount has increased significantly over the past decade, reaching $3.5 million as of January 2024. This trend underscores the importance of choosing the right funding vehicle and approach.

Looking ahead, I'm bullish on Houston's growing startup ecosystem flourishing further. Expect more capital formation from recycled wins, especially once recently minted unicorns like High Radius, Cart.com, Solugen, and Axiom Space exit and infuse the ecosystem with fresh and hungry angels, new platforms beyond traditional venture models, and evolving founder demographics bringing fresh perspectives.

------

Adrianne Stone is the principal product manager at Big Cartel and the founder of Bayou City Startups, a monthly happy hour organizer. This article original ran on LinkedIn.

Ad Placement 300x100
Ad Placement 300x600

CultureMap Emails are Awesome

These 5 trailblazing Houston startups are leading the energy transition

meet the finalists

Houston is home to a growing number of startups reshaping what it means to be called the "Energy Capital of the World."

As part of the 2026 Houston Innovation Awards, our Energy Transition Business category honors those innovative startups that are providing solutions within renewables, climatetech, clean energy, alternative materials, circular economy and more.

Five clean energy startups have been named finalists for the 2026 award. The finalists, selected by our esteemed panel of judges, range from a lower-emission steel producer to a diagnostics platform developer working to support batteries used in data centers.

Read more about these innovative businesses, their initiatives, and their inspirational founders below. The 2026 winners will be announced on InnovationMap.com in mid-November.

Capwell Services

Methane capture company Capwell Services works to eliminate vented oil and gas emissions economically for operators. According to the company, methane emissions are vented from most oil and gas facilities due to safety protocols, and operators are not able to capture the gas cost-effectively, leading operators to emit more than 14 million metric tons of methane per year in the U.S. and Canada. Founded in 2022, Capwell specializes in low and intermittent flow vents for methane capture.

The company began as a University of Pennsylvania senior design project led by CEO Andrew Lane. It has since participated in programs with Greentown Labs, the Rice Clean Energy Accelerator and the Creative Destruction Lab Energy Cohort at Texas A&M University. The company moved to Houston in 2023 and raised a pre-seed round. It deployed two commercial units this year, according to its application.

FlowCellutions

Energytech startup FlowCellutions is developing a chemistry-agnostic diagnostics platform for flow and metal-air batteries supporting data centers and critical infrastructure. The platform is designed to help reduce operating costs, prevent failures and costly downtime, and extend battery lifetime from approximately seven years to more than 30 years. It has deployed four paid pilots and plans to take insights from the programs to develop its next-gen sensor platform technology.

CEO Becca Segel founded the company in 2022. It is a member of Greentown Labs, and Segel was a 2025 Activate Fellow. The company has raised over $2 million in non-dilutive funding and received a $1.5 million NSF SBIR Fast-Track award earlier this year.

Hertha Metals

Hertha Metals produces lower-cost, lower-emission steel and high-purity iron. The company has developed a single-step process that uses natural gas as a direct reductant instead of metallurgical coal, which cuts production costs by more than 25 percent and emissions by up to 50 percent, according to the company. The same process produces high-purity iron needed for high-purity steels and rare earth magnets. The company says it aims to "re-industrialize America’s production of critical materials."

Hertha Metals was founded by CEO Laureen Meroueh in 2022 and emerged from stealth last year with more than $17 million in venture capital funding. The company closed a $133.65 million Series A this month and also broke ground on its $100M high-purity iron factory known as Chalyx in Conroe.

Mars Materials

Clean chemical manufacturing business Mars Materials is working to convert captured carbon into resources, such as carbon fiber and wastewater treatment chemicals. The company develops and produces its drop-in chemical products in Houston and uses an in-licensed process for the National Renewable Energy Lab to produce acrylonitrile, which is used to produce plastics, synthetic fibers, and rubbers.

Founded in 2019 by CEO Aaron Fitzgerald, CTO Kristian Gubsch, and vice president of operations Trey Sheridan, the company has secured over $7.2M in financing and is backed by Bill Gates’ Breakthrough Energy, Shell, Black & Veatch, and other organizations. It won in the Minority-founded Business Category in last year's Houston Innovation Awards.

Solidec

Chemical manufacturing company Solidec has developed autonomous generators that extract molecules from water and air and convert them into pure chemicals and fuels that are free of carbon emissions on-site, eliminating the need for transport, storage, and permitting. The company was founded around innovations developed by Rice University associate professor Haotian Wang.

The company was selected for the Chevron Technology Ventures’ Catalyst Program, Greentown Labs, NSF I-Corps and was part of the first cohort of the Activate Houston program. It won first place at the 2024 startup pitch competition at CERAWeek. Solidec was founded in 2023 by Wang, who serves as an advisor, CEO Ryan DuChanois, and CTO Yang Xia. It closed a $2.5 million seed round in 2025.

Houston businessman and philanthropist to receive legendary Texas award

Making History

The Texas State History Museum Foundation (TSHMF) has set the date for its 23rd annual Texas Independence Day Dinner and unveiled the 2027 recipients of its prestigious History-Making Texan Award, which includes a prominent Houston businessman.

Since 2005, the organization has honored "living Texas legends whose contributions to the state and the nation have been truly historic and exceptional in scope and nature." Past galas have recognized prominent Texas figures such as former presidents George H.W. and George W. Bush and former first ladies Barbara and Laura Bush, as well as H-E-B chairman Charles Butt, among others.

The two 2027 History-Making Texan Award recipients are Texas Historical Commission chairman, businessman, and philanthropist John L. Nau, III, and trailblazing Texas actor, director, producer, and writer Taylor Sheridan. The 2027 gala will be held at the Bullock Texas State History Museum in Austin on March 2, Texas Independence Day.

"Our honorees are national leaders whose accomplishments have elevated Texas’ distinctive place on the national and international stage," Debbie Raynor, dinner chair and TSHMF Trustee, said in a statement. "John L. Nau, III and Taylor Sheridan have each, in very different ways, helped tell the Texas story — one through the preservation of our history and treasured places, the other through the power of storytelling that has brought Texas and the American West to audiences around the world.

"Nau is the former chairman and CEO of Silver Eagle Beverages, one of the largest Anheuser-Busch distributors in the U.S. He has served as chairman of the Texas Historical Commission since 2015. Raynor said Nau's "commitment to preservation" extends further than his protection of Texas historic sites "to the stewardship and conservation of the land itself, including his bay area lodge in South Texas and his ranch in West Texas.

"[Nau's] leadership and lifelong dedication to history have earned him national recognition, but perhaps his greatest legacy is his determination to ensure that the stories and places that shaped Texas endure for generations to come," Raynor said.Quadruple-threat filmmaker Sheridan is most widely recognized for his award-winning neo-Western TV series Yellowstone and its associated spin-offs 1883, 1923, Marshals, and Dutton Ranch. Raynor hailed Sheridan for his success in bringing a "remarkable new dimension to the way the world sees Texas and the American West."

"As a creator, writer, director, and executive producer of some of television’s most successful series, he has captured the imagination of audiences across the globe while bringing the people, landscapes, traditions and enduring spirit of the West into millions of homes," she said. "And he does more than tell the Texas story — he lives it, as a native Texan, accomplished horseman and steward of two legendary Texas ranches."

A release estimates about 450 "business, political, and community leaders" attend the Texas Independence Day Dinner each year, and proceeds will benefit the Bullock Museum's educational programs and special projects.

The 2027 Texas Independence Day Dinner will take place March 2, 2027, at the Bullock Museum in Austin. A VIP reception will start at 6:30 pm, followed by a 7 pm reception, and 7:30 dinner and program.

---

This article first appeared on CultureMap.com.

Houston bio-based materials startup breaks into footwear

cleaner shoes

A more sustainable shoe can’t be built on a single material swap. From the hard plastics hidden inside a heel to the material covering a sneaker’s upper, footwear is a collection of components—and each presents a different challenge for companies trying to move away from conventional, petroleum-based materials.

Houston-based Rheom Materials wants to change that equation. The biomaterials company has launched a sustainable footwear platform featuring two of its bio-based alternatives: Benree, a biodegradable plastic designed for hard internal components, and ShoraiDura, a durable leather alternative for footwear uppers.

“A shoe is not one material; it is multiple parts working together as a system. Substituting a single material has never moved the needle,” Rheom founder and CEO Zimri Hinshaw said in a news release. “Rheom wants to make it easier for brands to make a positive impact. By providing an assortment of bio-based materials, brands can change the system, not just a swatch of it.”

Benree is Rheom’s alternative to conventional hard plastics used in footwear construction. The company says it is a 100 percent USDA-certified bio-based, biodegradable material with performance comparable to acrylonitrile butadiene styrene (ABS), a widely used engineering plastic.

The material has passed SATRA testing for high-heel applications with Bared Footwear, an Australian footwear brand.

“At Bared, we're constantly on a journey to remove plastic from our shoes. At the same time, our brand won't compromise on quality for the end customer,” Millie Richards, Bared’s head of sustainability, added in the release. “From samples and testing, Rheom has proven to be solving both of those problems for us. We look forward to seeing how they develop as a company and would love to use them in our shoes.”

Rheom says it is also exploring Benree for additional internal components, including toe puffs and heel counters.

Rheom's Benree material was used for a high-heel prototype. Photo courtesy Rheom Materials

The company’s ShoraiDura material addresses another major part of shoe construction: the upper, which must withstand repeated flexing, friction and wear while maintaining its appearance.

Containing about 80 percent bio-based content, ShoraiDura is engineered as a durable leather alternative for footwear. Rheom says the material’s molecular structure is designed to deliver the strength and durability required for demanding applications.

To demonstrate how the material could be used in finished products, Rheom worked with a Los Angeles-based footwear manufacturer to create two prototypes: an athletic sneaker and a textured skater shoe, both featuring ShoraiDura uppers.

The two offerings reflect the company’s broader strategy. Rather than asking brands to evaluate a single material in isolation, Rheom is positioning its platform as a way to explore alternatives across different parts of footwear construction.

The next step is broader industry adoption. Benree’s testing with Bared Footwear and ShoraiDura’s footwear prototypes offer early examples of how the materials could be applied, while commercial use will depend on manufacturers’ evaluations and product-development decisions.

Rheom Materials is a Houston-based biomaterials company developing bio-based alternatives to petrochemical plastics. Its product portfolio includes Shorai, a leather alternative, and Benree, a hard plastic alternative.

The company debuted Shorai at the Houston Livestock Show and Rodeo in 2025 and showed a bio-based "leather" collection in Milan earlier this year. Read more here.