Update date: Jul 08, 2026 | 296 Pages | Report ID: SFC-004094
Hydrochloric Acid Semiconductor Grade Market
DMA IntelligenceHydrochloric Acid Semiconductor Grade Strategic Insights & Forecast Outlook 2033
Segments: Purity Level (Ultra-High Purity, High Purity, Standard Purity), Application (Etching, Cleaning, Doping, Others), End-Use Industry (Integrated Circuits, Solar Cells, LEDs, Photovoltaics, Others), Distribution Channel (Direct Sales, Distributors, Others), By Region, And Segment Forecasts
$250.0M
Market Size, 2025
$271.3M
Market Estimate, 2026
$480.2M
Market Forecast, 2033
8.5%
CAGR, 2026–2033
Market Definiton and Strategic Context
The Hydrochloric Acid Semiconductor Grade Market refers to the specialized segment of the chemical industry focused on producing extremely high-purity hydrochloric acid specifically tailored for semiconductor manufacturing processes. This critical chemical is indispensable in various stages of semiconductor fabrication, including etching, cleaning, and doping, where even trace impurities can compromise device performance and yield. The market is driven by the relentless demand for smaller, more powerful, and energy-efficient electronic components, necessitating increasingly stringent quality standards for process chemicals. The global Hydrochloric Acid Semiconductor Grade market size reached USD 250.00 Million in 2025, with a robust growth outlook projected to expand significantly over the forecast period. The industry expansion is intrinsically linked to advancements in semiconductor technology, such as the transition to smaller node sizes and the proliferation of advanced packaging techniques, which require ultra-clean manufacturing environments and high-purity materials. Market forecast indicates sustained growth, fueled by investments in new fabrication plants (fabs) and research & development efforts aimed at optimizing semiconductor manufacturing processes. Key players are continually investing in advanced purification technologies and supply chain optimization to meet the evolving demands of the semiconductor industry. The stringent regulatory landscape and the high capital expenditure required for production facilities further define this niche market. Understanding the dynamics of this market is crucial for stakeholders across the semiconductor value chain, from material suppliers to device manufacturers, as it directly impacts production efficiency, product quality, and competitive advantage. The market is also influenced by geopolitical factors and regional manufacturing shifts, particularly the expansion of semiconductor production capacities in Asia Pacific, which is emerging as a dominant hub for both manufacturing and consumption of these specialized chemicals. The demand for Hydrochloric Acid Semiconductor Grade is thus a direct reflection of the overall health and growth trajectory of the global electronics and semiconductor industry.
| Report Attribute | Details |
|---|---|
| Market size value in 2025 | USD 250.00 Million |
| Revenue forecast in 2033 | USD 480.15 Million |
| Growth rate | CAGR of 8.5% from 2025 to 2033 |
| Actual data | 2021 - 2024 |
| Forecast period | 2025 - 2033 |
| Quantitative units | Revenue in USD Million and CAGR from 2025 to 2033 |
| Report coverage | Revenue forecast, company share, competitive landscape, growth factors, and trends |
| Segments covered | Purity Level, Application, End-Use Industry, Distribution Channel |
| Regional scope | North America; Europe; Asia Pacific; Rest of Asia Pacific; Latin America; Middle East & Africa |
| Country scope | United States; Canada; Germany; France; Italy; United Kingdom; Spain; Russia; Rest of Europe; China; Japan; South Korea; India; Australia; South East Asia (SEA; All; Mexico; Brazil; Rest of Latin America; Saudi Arabia; South Africa; United Arab Emirates; Rest of Middle East & Africa |
| Key companies profiled | BASF SE; Olin Corporation; Westlake Chemical Corporation; Detrex Corporation; INEOS Group Holdings S.A.; AGC Inc.; Tosoh Corporation; KMG Chemicals (a part of Cabot Microelectronics); Solvay S.A.; Occidental Petroleum Corporation (OxyChem); Shin-Etsu Chemical Co., Ltd.; Sumitomo Chemical Co., Ltd.; Dongyue Group Limited; Formosa Plastics Corporation; Sanmar Group; Hasa Inc.; Unid Co., Ltd.; Gujarat Alkalies and Chemicals Limited (GACL); Grasim Industries Limited (Aditya Birla Group); Covestro AG |
| Customization scope | Free report customization (equivalent to 8 analysts working days) with purchase. Addition or alteration to country, regional & segment scope. |
| Pricing and purchase options | Avail customized purchase options to meet your exact research needs. Explore purchase options |
Growth Catalysts & Market Constraints
The Hydrochloric Acid Semiconductor Grade market is experiencing dynamic shifts influenced by several key factors driving its expansion and posing notable challenges. The continuous innovation in semiconductor technology, characterized by the pursuit of smaller feature sizes and higher transistor density, directly underpins the demand for ultra-pure process chemicals. This trend translates into a positive growth forecast for the Hydrochloric Acid Semiconductor Grade market size, as manufacturers require increasingly sophisticated and contamination-free solutions for critical etching and cleaning steps. However, the market also contends with supply chain vulnerabilities and the high cost associated with maintaining the required purity levels, which can impact profitability and market stability. Strategic investments in R&D and manufacturing capacity are essential for companies to navigate these dynamics and capitalize on emerging opportunities within this specialized industry.
Growth Drivers
- Expanding global semiconductor industry: The relentless demand for electronic devices, including smartphones, AI hardware, and IoT devices, fuels the growth of semiconductor manufacturing, which in turn drives the consumption of high-purity hydrochloric acid for crucial processes like etching and cleaning, ensuring consistent quality and performance of advanced chips.
- Technological advancements in semiconductor fabrication: The transition to smaller process nodes (e.g., 5nm, 3nm) and the adoption of advanced packaging technologies necessitate even higher purity chemicals to prevent defects and improve yield. This demand for ultra-clean materials directly propels innovation and market expansion for Hydrochloric Acid Semiconductor Grade products.
Restraints
- High production cost and capital expenditure: Manufacturing ultra-high purity hydrochloric acid requires significant investment in specialized purification technologies, cleanroom facilities, and stringent quality control, leading to high production costs that can limit market entry for new players and pressure profit margins for existing ones.
- Stringent regulatory compliance and environmental concerns: The production and handling of hydrochloric acid are subject to strict environmental regulations and safety standards. Compliance with these complex rules adds operational costs and can sometimes hinder facility expansion or lead to production limitations, impacting market growth.
Opportunities
- Emergence of new semiconductor manufacturing hubs: The establishment of new fabrication plants (fabs) in regions like Southeast Asia and North America, driven by geopolitical strategies and supply chain diversification, presents significant opportunities for suppliers to expand their geographical reach and cater to growing regional demand.
- Development of advanced purification technologies: Continuous innovation in purification methods, such as advanced filtration and distillation techniques, can enable manufacturers to achieve even higher purity levels more efficiently, opening doors for new product offerings and enhancing competitive advantage in this highly specialized market.
Challenges
- Supply chain disruptions and raw material volatility: The specialized nature of raw material sourcing and complex logistics for high-purity chemicals make the supply chain vulnerable to disruptions, such as geopolitical events or natural disasters, leading to price volatility and potential shortages that impact semiconductor production schedules.
- Intense competition and pricing pressures: The market is characterized by a limited number of specialized suppliers, yet competition remains fierce due to the critical nature of the product and the high cost of switching suppliers. This can lead to pricing pressures and the need for continuous cost optimization to maintain market share.
Market Level Breakdown
The Hydrochloric Acid Semiconductor Grade market is meticulously segmented by purity level, reflecting the critical demands of semiconductor manufacturing. High Purity hydrochloric acid, while essential for certain processes, represents a foundational segment. Ultra-High Purity commands a significant share, catering to the mainstream fabrication needs of current generation chips. The Mega-Purity segment, with its extremely low impurity levels, is rapidly growing due to the increasing adoption of advanced nodes and specialized applications, underscoring a key trend in the Hydrochloric Acid Semiconductor Grade segmentation as manufacturers push the boundaries of chip technology.
Segmentation by application highlights the diverse uses of hydrochloric acid within semiconductor production. Etching remains a primary application, crucial for patterning semiconductor wafers, while cleaning processes, vital for removing contaminants at various stages, also hold a substantial market share. Doping applications, which involve introducing impurities to alter semiconductor properties, and other specialized uses collectively contribute to the market’s overall revenue. Each application demands specific purity and concentration, influencing product development and market dynamics.
The end-use industry segmentation showcases the broad impact of semiconductor-grade hydrochloric acid. Integrated Circuit (IC) Manufacturing is the largest consumer, reflecting the immense scale of chip production for various electronic devices. Photovoltaics, Flat Panel Displays, and LED Manufacturing also represent significant end-use industries, each with specific requirements for high-purity chemicals. This segmentation underscores the pervasive role of semiconductors in modern technology and the corresponding demand for specialized process materials like hydrochloric acid.
Distribution channel segmentation outlines how these specialized chemicals reach their end-users. Direct sales channels are often preferred for large-volume orders and for customers requiring bespoke solutions or direct technical support from manufacturers. Distributors play a crucial role in reaching a broader customer base, including smaller fabs or specialized research facilities, by managing logistics and localized inventory. Online retail, while nascent, is emerging for certain standardized products or for initial procurements, reflecting a gradual shift in procurement strategies within the Hydrochloric Acid Semiconductor Grade market taxonomy.
Hydrochloric Acid Semiconductor Grade Segmentation Breakdown
- Purity Level
- Ultra-High Purity
- High Purity
- Standard Purity
- Application
- Etching
- Cleaning
- Doping
- Others
- End-Use Industry
- Integrated Circuits
- Solar Cells
- LEDs
- Photovoltaics
- Others
- Distribution Channel
- Direct Sales
- Distributors
- Others
Geographic Performance & Regional Trends
Asia Pacific stands out as the dominant region in the Hydrochloric Acid Semiconductor Grade market, accounting for 45% of the market consumption in 2025, and is also projected to be the fastest-growing market. This leadership is primarily attributed to the region's robust and expanding semiconductor manufacturing ecosystem, with countries like China, South Korea, Japan, and Taiwan being global hubs for chip production. Significant investments in new fabrication plants, government initiatives supporting domestic semiconductor industries, and a large consumer electronics market drive the demand for high-purity chemicals. North America and Europe follow, with established semiconductor industries and strong R&D capabilities, though their growth rates are generally more mature compared to the dynamic Asia Pacific region. The Hydrochloric Acid Semiconductor Grade market growth is intrinsically linked to these regional manufacturing shifts.
Regional Growth Drivers
- North America: The region benefits from significant government investments in reshoring semiconductor manufacturing, such as the CHIPS Act in the United States, fostering the establishment of new fabs and expanding existing facilities. This strategic push aims to enhance supply chain resilience and increase domestic chip production, directly boosting demand for high-purity chemicals.
- Europe: Driven by initiatives like the European Chips Act, Europe is accelerating investments in R&D and advanced semiconductor manufacturing capabilities, particularly in countries like Germany, France, and the Netherlands. This focus on innovation and domestic production strengthens the regional demand for specialized hydrochloric acid.
- Asia Pacific: The region's unparalleled dominance in semiconductor manufacturing, led by China, South Korea, Japan, and Taiwan, continues to be a primary growth engine. Rapid industrialization, a massive consumer electronics market, and continuous expansion of fabrication capacities solidify its position as the largest and fastest-growing market.
- Latin America: Modernization efforts in existing industrial sectors and a burgeoning electronics assembly industry, particularly in countries like Brazil and Mexico, are slowly increasing the demand for high-purity chemicals. While smaller, the region offers potential for gradual market expansion as local manufacturing capabilities develop.
- Middle East & Africa: Emerging economies in the Middle East are investing in diversifying their industrial bases, with nascent efforts in electronics manufacturing and assembly. Infrastructure upgrades and government-led industrialization programs, notably in Saudi Arabia and the UAE, are creating new, albeit smaller, pockets of demand for semiconductor-grade materials.
The regional forecast indicates a sustained shift towards Asia Pacific, which will continue to lead in both production and consumption due to ongoing investments and government support for its semiconductor industry. Mature markets in North America and Europe, while experiencing steady growth, will focus more on advanced R&D and niche high-value applications, aiming for technological leadership rather than sheer volume. Suppliers will need to adapt their strategies, focusing on localized production and robust supply chains in Asia Pacific, while emphasizing innovation and technical support in Western markets to cater to diverse regional trajectories and capitalize on the global Hydrochloric Acid Semiconductor Grade market growth.
Competitive Insights & Leading Companies
The Hydrochloric Acid Semiconductor Grade competitive landscape is characterized by a moderately consolidated structure, with a few global giants dominating the market alongside several specialized regional players. Competition primarily revolves around product purity, consistent supply, technical support, and pricing. Global players leverage their extensive manufacturing capabilities, integrated supply chains, and strong R&D investments to maintain a competitive edge. These companies often have a broad portfolio of high-purity chemicals, enabling them to offer comprehensive solutions to semiconductor manufacturers. Regional players, on the other hand, focus on niche markets or specific purity levels, often capitalizing on proximity to key fabrication plants and offering localized services. Key competitive levers include adherence to ultra-stringent quality standards, reliable logistics, and the ability to innovate purification technologies to meet evolving semiconductor industry demands. Regulatory approvals and certifications, such as ISO and SEMI standards, are critical entry barriers and differentiators, ensuring product quality and safety throughout the supply chain. The high capital expenditure required for production facilities and the complex technical expertise further limit the number of active participants, contributing to the market's consolidated nature. Market participants prioritize long-term supply agreements and strong customer relationships due to the critical nature of these materials in semiconductor manufacturing, influencing the overall Hydrochloric Acid Semiconductor Grade competitive landscape.
Companies in the Hydrochloric Acid Semiconductor Grade market employ various strategies to strengthen their position, including mergers and acquisitions, strategic partnerships, and continuous product innovation. M&A activities often aim to consolidate market share, acquire specialized technologies, or expand geographical reach. Strategic partnerships with semiconductor manufacturers are crucial for co-developing new chemical formulations that meet future technological requirements and for securing long-term supply contracts. Product launches focus on introducing even higher purity grades or developing customized solutions for specific fabrication processes, such as advanced etching techniques or specialized cleaning protocols for 3D NAND and FinFET structures. R&D investments are paramount for developing next-generation purification methods and analytical techniques to detect and remove sub-parts-per-trillion impurities. Differentiation is achieved through superior product consistency, exceptional technical service, and robust supply chain management, ensuring just-in-time delivery to sensitive fabs. Localization of manufacturing and distribution facilities is also a growing trend, driven by geopolitical concerns and the need for more resilient supply chains. Despite these efforts, companies face challenges such as margin pressure due to intense competition and the high cost of maintaining ultra-clean production environments. Compliance costs associated with environmental regulations and safety standards also pose a significant burden, while the risk of supply chain disruptions for critical raw materials remains a constant concern for the Hydrochloric Acid Semiconductor Grade key players.
Hydrochloric Acid Semiconductor Grade Key Companies
- BASF SE
- Olin Corporation
- Westlake Chemical Corporation
- Detrex Corporation
- INEOS Group Holdings S.A.
- AGC Inc.
- Tosoh Corporation
- KMG Chemicals (a part of Cabot Microelectronics)
- Solvay S.A.
- Occidental Petroleum Corporation (OxyChem)
- Shin-Etsu Chemical Co., Ltd.
- Sumitomo Chemical Co., Ltd.
- Dongyue Group Limited
- Formosa Plastics Corporation
- Sanmar Group
- Hasa Inc.
- Unid Co., Ltd.
- Gujarat Alkalies and Chemicals Limited (GACL)
- Grasim Industries Limited (Aditya Birla Group)
- Covestro AG
Hydrochloric Acid Semiconductor Grade Market Ecosystem
Ecosystem Participants
- Raw Material Suppliers — provide essential foundational chemicals like hydrogen and chlorine, which are then processed to produce hydrochloric acid. Their role is critical in ensuring the initial purity and consistent availability of precursors, directly impacting the quality and cost-effectiveness of the final semiconductor-grade product.
- These suppliers must adhere to strict quality controls, as any impurities introduced at this stage can be challenging and costly to remove in subsequent purification steps. Long-term contracts and strategic partnerships with reliable raw material providers are common to mitigate supply chain risks.
- Manufacturers/Producers — specialize in the ultra-purification and refinement of hydrochloric acid to meet stringent semiconductor industry specifications. They invest heavily in advanced distillation, filtration, and analytical techniques to achieve parts-per-trillion purity levels, ensuring the chemical is free from metallic ions, particles, and organic contaminants.
- These companies are responsible for the actual chemical synthesis and purification, often operating in highly controlled cleanroom environments to prevent contamination. Their expertise in chemical engineering and process optimization is paramount for maintaining product integrity and consistency.
- Distributors/Suppliers — manage the logistics, storage, and timely delivery of the highly sensitive semiconductor-grade hydrochloric acid to fabrication plants. They often provide localized inventory, technical support, and specialized handling services, acting as a crucial link between manufacturers and end-users.
- Given the hazardous nature and purity requirements of the product, these distributors must possess specialized infrastructure for transportation and storage, including temperature-controlled facilities and inert packaging, to prevent degradation or contamination during transit.
- Semiconductor Manufacturers (End-Users) — are the primary consumers of hydrochloric acid semiconductor grade, utilizing it in various stages such as wet etching of silicon wafers, cleaning of process equipment, and surface preparation before deposition steps. Their demand dictates the market's growth and purity requirements.
- These companies continually push for higher purity standards and consistent product performance to optimize their fabrication yields and enable the production of advanced microprocessors, memory chips, and other integrated circuits.
- Equipment Manufacturers — develop and supply the specialized tools and machinery used in semiconductor fabrication, including wet processing stations, etchers, and cleaning baths. They often collaborate with chemical suppliers to ensure compatibility and optimal performance of the chemicals within their equipment.
- Their innovations in process technology often drive the need for new or enhanced chemical formulations, creating a synergistic relationship within the ecosystem that fosters continuous improvement in semiconductor manufacturing.
- Regulatory Bodies and Industry Associations — establish and enforce the safety, environmental, and quality standards for chemical production and usage in the semiconductor industry. Organizations like SEMI (Semiconductor Equipment and Materials International) define purity specifications and handling guidelines.
- Their oversight ensures that manufacturers adhere to best practices, promoting worker safety, environmental protection, and product reliability across the entire value chain, which is crucial for maintaining industry integrity and public trust.
- Research & Development Institutions — academic and private research entities that contribute to the advancement of purification technologies, analytical methods, and new applications for high-purity chemicals in future semiconductor processes. They often work in collaboration with manufacturers to innovate.
- Their work helps anticipate future material requirements and overcome existing technical challenges, playing a vital role in the long-term technological evolution of the semiconductor industry and the Hydrochloric Acid Semiconductor Grade market.
Report Coverage & Key Deliverables
The report delivers a comprehensive analysis of the Hydrochloric Acid Semiconductor Grade, combining quantitative data with qualitative insights. This exhaustive study provides an in-depth understanding of market trends, drivers, restraints, and opportunities, offering a panoramic view of the industry's past, present, and future trajectory. It is meticulously designed to serve as an indispensable resource for stakeholders, including manufacturers, suppliers, distributors, and investors, enabling them to make informed strategic decisions. The report encompasses detailed market sizing, segmentation analysis, regional breakdowns, and competitive landscape assessments, all presented with clarity and precision. By integrating robust market data with expert analysis, it aims to clarify complex industry dynamics, highlight lucrative growth avenues, and identify potential challenges. This ensures that readers gain actionable intelligence to navigate the evolving market, optimize their operations, and formulate effective business strategies. The report's scope is tailored to provide a holistic perspective, covering both established and emerging trends that are shaping the Hydrochloric Acid Semiconductor Grade market, ultimately empowering businesses to enhance their competitive positioning and drive sustainable growth in a dynamic global environment.
Report Coverage
- Market Size Estimates (historical and forecast)
- This section provides comprehensive market value data spanning the historical period from 2021 to 2025 and extends to a detailed forecast through 2033. It includes precise revenue figures in USD Million, offering a clear understanding of market evolution and future projections based on rigorous analytical methodologies and growth models.
- Detailed Segmentation And Revenue Analysis
- The report meticulously segments the Hydrochloric Acid Semiconductor Grade market by purity level, application, end-use industry, and distribution channel, providing granular revenue analysis for each sub-segment. This breakdown helps identify key growth areas and understand the specific market contributions of diverse product categories and end-user demands.
- Regional And Country-Level Insights
- An in-depth geographical analysis covers North America, Europe, Asia Pacific, Latin America, and Middle East & Africa, including specific country-level data. This section contrasts market maturity, growth drivers, and regulatory landscapes across regions, highlighting critical differences and strategic implications for global market players.
- Competitive Benchmarking Of Key Players
- This segment offers a thorough assessment of the competitive landscape, profiling leading companies based on their market share, product portfolios, strategic initiatives, and R&D activities. It provides insights into their strengths, weaknesses, opportunities, and threats, aiding in competitive positioning and strategic planning.
- Customization Options Based on Specific Requirements
- Clients can request tailored modifications to the report's scope, including additional segment breakdowns, specific country analysis, or deeper dives into particular competitive aspects. This flexibility ensures the report directly addresses unique business intelligence needs, offering bespoke insights and deliverable flexibility beyond the standard offering.
Recent Industry Insights
The Hydrochloric Acid Semiconductor Grade industry trends over the last 12-18 months reflect a strong focus on supply chain resilience, advanced purification technologies, and strategic regional expansion. Geopolitical shifts have spurred investments in domestic semiconductor manufacturing, particularly in North America and Europe, aiming to diversify supply sources away from concentrated regions. This has led to increased demand for localized high-purity chemical production. Furthermore, the continuous push for smaller process nodes in chip manufacturing has intensified the need for even higher purity chemicals, driving R&D into novel purification methods and analytical capabilities. Companies are also forming more strategic partnerships with end-users to co-develop tailored solutions, ensuring product compatibility with next-generation fabrication processes. These developments underscore a dynamic market responding to both technological imperatives and global economic restructuring, shaping the future trajectory of the Hydrochloric Acid Semiconductor Grade market.
Key Market Developments
- January 2025: SK Siltron announced plans for a new silicon carbide wafer manufacturing facility in the United States, increasing demand for ultra-high purity process chemicals.
- October 2024: Merck KGaA (operating as EMD Electronics in North America) expanded its high-purity chemical production capacity in Taiwan to support growing demand from advanced foundries.
- July 2024: Samsung Foundry invested significantly in its South Korean fabs to accelerate 2nm process development, requiring stricter specifications for all incoming materials, including hydrochloric acid.
- April 2024: Intel broke ground on new manufacturing facilities in Germany, signaling a major expansion of European semiconductor production and creating new regional demand for high-purity chemicals.
- February 2024: A leading chemical supplier launched a new mega-purity grade of hydrochloric acid, specifically designed for extreme UV (EUV) lithography applications, catering to the most advanced semiconductor manufacturing processes.
Analyst Opinion
The Hydrochloric Acid Semiconductor Grade market outlook remains highly attractive, driven by the indispensable role of ultra-pure chemicals in the ever-advancing semiconductor industry. The market's attractiveness stems from the non-substitutable nature of hydrochloric acid in critical fabrication steps like etching and cleaning, coupled with the continuous demand for higher purity levels as chip technology evolves. Competitive intensity is high among a relatively small number of specialized global and regional players, primarily focused on technological superiority, supply chain reliability, and customer-specific solutions rather than aggressive price competition. The demand-supply balance is currently stable but susceptible to regional geopolitical dynamics and raw material availability, necessitating robust supply chain management by key players. Investment in R&D for advanced purification techniques and localized production capabilities are crucial for sustained growth and market leadership. The market is not merely about chemical supply but about providing a critical enabler for the global digital economy, making it a high-value, high-barrier-to-entry segment within the broader chemicals industry. This unique positioning ensures strong long-term prospects, provided companies can navigate the complex regulatory and technological landscape effectively.
Looking at the long-term Hydrochloric Acid Semiconductor Grade market outlook, the industry is poised for sustained growth, fueled by megatrends such as artificial intelligence, 5G, IoT, and electric vehicles, all of which rely on advanced semiconductors. The innovation landscape will be dominated by advancements in purification technologies, enabling the production of chemicals with even fewer impurities at sub-parts-per-trillion levels, crucial for future process nodes. Furthermore, there will be a growing emphasis on sustainable manufacturing practices, including greener production processes and improved waste management, driven by increasing environmental regulations and corporate responsibility. Key risk factors include geopolitical tensions impacting global supply chains, the high capital intensity required for facility upgrades, and the continuous need to adapt to rapidly evolving semiconductor manufacturing processes. Companies that can demonstrate agility in R&D, secure diversified raw material sources, and build strong, localized customer relationships will be best positioned for success. The future of the market will also see increased collaboration between chemical suppliers and semiconductor foundries, fostering co-innovation to address the intricate challenges of next-generation chip fabrication and ensuring the continued availability of essential, ultra-pure materials.