From Sea to Sheet: The Fascinating Process of How Korean Gim (Seaweed) is Made

Table of Contents

1. Why is the World Obsessed with Korean Gim?
2. Step 1: The Heart of the Harvest – The Bustling ‘Mul-gim’ Auction
3. Step 2: The "Papermaking" Transformation – From Raw Slurry to Dried Sheets
4. Phase 1: Cleaning and Creating the ‘Wonchoaek’ (Raw Laver Liquid)
5. Phase 2: Shaping and Drying – The Birth of ‘Mareun-gim’
6. The Final Product: More Than Just a Sheet
7. Conclusion: A Taste of the Korean Sea, Made with Precision

Why is the World Obsessed with Korean Gim?

Walk into any grocery store from New York to London, and you’ll likely spot those familiar green packages of crispy Korean seaweed snacks. Korean gim (김) has become a global phenomenon, riding the wave of K-food’s international popularity alongside kimchi and Korean fried chicken. This humble sea vegetable has evolved from a traditional Korean staple into one of Korea’s top seafood exports, reaching over $790 million in sales in 2023 and capturing more than 70% of the global seaweed market.

But while millions enjoy these paper-thin, umami-rich sheets as convenient snacks or essential ingredients in gimbap (Korean seaweed rice rolls), few understand the remarkable journey that transforms fresh, wet seaweed harvested from Korea’s coastal waters into the crispy delicacy we know and love. The process is far more fascinating than you might imagine—combining centuries-old Korean traditions with modern automation, early-morning auctions, and production techniques surprisingly similar to traditional papermaking.

In this guide, we’ll follow the complete transformation of mul-gim into mareun-gim, revealing the intricate steps that bring this Korean superfood from ocean to table. Understanding this process not only deepens your appreciation for Korean culinary culture but also highlights why gim holds such a special place in Korean food culture and traditions.

Key Terms You’ll Need:

1. Mul-gim (물김): Fresh, wet laver straight from the ocean—the raw material for all gim products
2. Mareun-gim (마른김): Dried, unseasoned gim sheets—the foundational product before roasting or seasoning
3. Wonchoaek (원초액): The raw laver slurry created by grinding and mixing mul-gim with water

Step 1: The Heart of the Harvest – The Bustling ‘Mul-gim’ Auction

Before dawn breaks over Korea’s southern coastal towns, a bustling scene unfolds that most gim consumers never witness. Mul-gim, the freshly harvested wet seaweed, arrives at coastal wipanjang (위판장)—wholesale auction markets where the day’s catch changes hands at breathtaking speed.

These early-morning auctions represent the critical first link in gim’s supply chain. Seaweed farmers harvest mul-gim during the optimal winter season, typically from December through April, when water temperatures hover between 5-8°C (41-46°F) and the laver reaches peak nutritional content and flavor. The harvest window is narrow and precious—after April, warming waters make the seaweed less suitable for quality gim production.

The wipanjang buzzes with energy as representatives from gim processing companies bid competitively on tons of freshly harvested mul-gim. These auctions are intense, fast-paced affairs where freshness is everything. Unlike many agricultural products that can be stored or transported slowly, mul-gim deteriorates rapidly. The seaweed must move from ocean to processing facility within hours to maintain the quality necessary for premium gim production.

Auction prices fluctuate based on multiple factors: the quality and thickness of the seaweed, the harvest location (certain coastal areas like Wando in South Jeolla Province are prized for superior gim), weather conditions affecting harvest volume, and market demand. In recent years, as global appetite for Korean gim has surged, auction prices have climbed significantly—wholesale prices for dried gim increased nearly 60% between 2023 and 2024, reflecting both strong international demand and periodic supply shortages.

For processing companies, securing high-quality mul-gim at these auctions is absolutely crucial. The raw material determines everything about the final product—its color, texture, aroma, and that characteristic oceanic umami flavor that makes Korean gim so distinctive. Experienced buyers can assess mul-gim quality at a glance, looking for the right color (dark purple to brownish-red), thickness, and absence of debris or damage.

According to Korea Tourism Organization, gim produced during winter in estuaries with optimal salinity levels is considered the most delicious, which explains why auction competition peaks during these months. Once purchased, the mul-gim is immediately transported to nearby processing facilities—often located strategically close to coastal auction sites—where the transformation into mareun-gim begins.

Step 2: The "Papermaking" Transformation – From Raw Slurry to Dried Sheets

The journey from soggy, dark-colored mul-gim to the crisp, paper-thin sheets we recognize requires a fascinating production process that’s been refined over generations. While modern gim factories utilize advanced automation and quality control systems, the fundamental technique remains remarkably similar to traditional methods—and, intriguingly, to the ancient Korean art of hanji (한지) papermaking.

Phase 1: Cleaning and Creating the ‘Wonchoaek’ (Raw Laver Liquid)

The moment mul-gim arrives at the processing facility, workers or automated systems initiate an intensive cleaning process. This stage is non-negotiable for producing high-quality gim, as fresh seaweed straight from the ocean carries sand particles, tiny shell fragments, microscopic marine organisms, and other debris that must be removed.

The mul-gim undergoes multiple rounds of washing in clean, filtered water. Depending on the facility and quality standards, this might involve three to five separate wash cycles, each removing progressively finer impurities. Modern facilities often employ automated washing systems with gentle agitation that cleans thoroughly without damaging the delicate seaweed structure.

Once pristinely clean, the mul-gim moves to the chopping and grinding stage. Here, the whole seaweed fronds are mechanically chopped into very small pieces, then mixed with carefully measured amounts of clean water. This grinding process creates the wonchoaek (원초액)—a dark, viscous slurry that looks somewhat like thick soup. The consistency of this mixture is critically important and requires precise control.

The concentration of wonchoaek directly determines the thickness and quality of the final gim sheets. Too much water creates thin, fragile gim that tears easily. Too little water produces overly thick sheets that don’t dry properly and lack the delicate texture consumers expect. Experienced production managers adjust the ratio based on the characteristics of that day’s mul-gim and the specific product being produced. Generally, gim for gimbap (kimbap-yong gim) is made slightly thicker, while traditional snacking gim (jaerae gim) is produced paper-thin to allow light to pass through when held up.

Phase 2: Shaping and Drying – The Birth of ‘Mareun-gim’

With the wonchoaek prepared, the production process enters its most fascinating phase—one that closely mirrors traditional Korean papermaking techniques. Just as hanji artisans create sheets of traditional paper by spreading pulp onto screens and allowing it to dry, gim makers transform seaweed slurry into uniform sheets through a remarkably similar process.

In traditional gim production, still practiced by some artisanal producers, craftspeople use a rectangular bamboo screen called a "bal" (발). The screen is dipped into the wonchoaek, lifted with a practiced swirling motion that distributes the seaweed evenly, then allowed to drain. This technique requires considerable skill—too much slurry creates thick spots, too little leaves holes, and uneven distribution produces inconsistent quality.

Modern factories have automated this process while maintaining the same fundamental principle. Automated production lines continuously form uniform sheets by spreading measured amounts of wonchoaek onto moving conveyor screens. The machinery precisely controls thickness, ensuring each sheet meets exact specifications. Some high-end producers still incorporate elements of traditional bal technique into their automated systems, believing it creates superior texture.

Once formed, the wet gim sheets move to the drying stage. Fresh gim contains approximately 90% water and must be reduced to around 10-12% moisture content for proper preservation and that characteristic crispy texture. Traditional producers once laid sheets on bamboo mats under the sun, relying on natural sunlight and sea breezes for drying. While some artisanal operations still use this method (particularly for premium dol-gim made from rock-grown seaweed), most modern production relies on large-scale industrial dryers that maintain precise temperature and humidity controls.

These dryers use carefully calibrated heat to evaporate moisture without cooking or burning the delicate seaweed. The drying temperature and duration vary based on sheet thickness and desired final characteristics, but generally occurs at relatively low temperatures to preserve the gim’s nutritional content, color, and flavor compounds. The sheets pass through the dryers on conveyor belts, emerging transformed—now lightweight, crispy, and dark green-black in color with that distinctive sheen.

Quality control occurs continuously throughout this process. Modern facilities employ both automated sensors and human inspectors to check for thickness uniformity, proper drying, absence of holes or debris, and correct color development. Sheets that don’t meet standards are removed and often repurposed for other products like gimjaban (crushed, seasoned gim flakes).

The entire process, from mul-gim arrival to finished mareun-gim sheets, typically completes within 24-48 hours. This speed is necessary both for quality preservation and to keep pace with the massive daily volumes required to meet global demand. Large Korean gim producers process tons of mul-gim daily during peak season, operating around the clock to maximize production during the limited harvest period.

The Final Product: More Than Just a Sheet

What emerges from this intricate process is mareun-gim—dried, unseasoned gim in its most basic form. These thin, dark sheets might not look particularly appetizing to the uninitiated, but they represent a versatile ingredient that forms the foundation of numerous Korean dishes and snack products.

Mareun-gim is the essential building block that other gim products start from. It has a subtle oceanic flavor and a paper-like texture that becomes wonderfully crispy when toasted. This is the gim that’s used to wrap gimbap (김밥), Korea’s beloved seaweed rice rolls that have become increasingly popular worldwide. Professional gimbap makers prefer slightly thicker mareun-gim that can hold fillings without tearing.

To create the seasoned gim snacks sold in colorful packages at grocery stores, producers take mareun-gim and lightly brush one side with oil (typically sesame or perilla oil) before sprinkling with sea salt. The sheets are then quickly toasted, either by passing them over heat or through specialized roasting equipment. This brief roasting transforms the gim, intensifying its umami flavor, creating an addictively crunchy texture, and developing those characteristic slightly greenish tones that indicate properly roasted gim.

Beyond snacking and gimbap, mareun-gim serves numerous culinary purposes in Korean cuisine. It’s torn into pieces and used as a garnish for soups like tteokguk (rice cake soup), crumbled and mixed with sesame oil and salt to create gimjaban (김자반) for topping rice bowls, or cut into small rectangles and served as banchan (side dishes) at Korean meals. Some traditional preparations, like gim-bugak (김부각), involve coating mareun-gim sheets with rice paste and deep-frying them to create a crispy, puffed snack.

The versatility of mareun-gim reflects centuries of Korean culinary creativity in working with this oceanic ingredient. Historical records show Koreans have consumed gim since at least the Goryeo Dynasty (918-1392 CE), and during the Joseon Dynasty (1392-1910), gim was so valued that coastal regions were required to provide it as royal tribute. The development of cultivation techniques in the 17th century, attributed to a farmer named Kim Yeo-ik who noticed seaweed growing on driftwood, dramatically expanded gim availability and cemented its place as a Korean staple.

Today, Korean gim has achieved remarkable global recognition. It’s exported to over 110 countries, with particularly strong markets in the United States, Japan, Thailand, and Europe. The rise of Korean pop culture and cuisine has introduced millions of international consumers to gim’s unique taste and texture, turning what was once an unfamiliar "weird seaweed thing" into a sought-after superfood snack. The global success has created challenges—supply sometimes struggles to meet demand, driving prices upward and prompting the Korean government to invest in expanding cultivation areas.

A Taste of the Korean Sea, Made with Precision

The next time you tear open a package of crispy Korean gim or unwrap a fresh gimbap roll, you’ll know the remarkable journey hidden within those thin sheets. From the predawn auction drama at coastal wipanjang to the papermaking-inspired production process, every piece of gim embodies centuries of Korean maritime tradition blended with modern innovation.

The transformation of mul-gim into mareun-gim involves far more than simple drying—it requires timing, skill, quality control, and a deep understanding of how this particular sea vegetable behaves. The washing must be thorough yet gentle, the wonchoaek concentration must be precisely calibrated, the forming process must distribute seaweed evenly, and the drying must remove moisture without sacrificing flavor or nutrition.

This intricate process has sustained Korean coastal communities for generations while evolving to serve a global market hungry for K-food’s distinctive flavors. The fact that Korean gim now represents over 70% of the global seaweed market speaks to both the excellence of Korean production methods and the universal appeal of this nutritious, delicious ingredient.

Have you experienced gim in different forms? Perhaps you’ve enjoyed it as a midnight snack, wrapped around rice at a Korean restaurant, or even discovered it at a convenience store. What’s your favorite way to eat this incredible gift from Korea’s seas? Share your gim stories in the comments below—we’d love to hear how this traditional Korean food has found its way into your life!