# Yantai Dasteck Chemicals Co., Ltd. > Yantai Dasteck Chemicals Co., Ltd. (brand: Dasteck Chemicals) is a Chinese chemical manufacturer established in 1958 and producing Thiourea Dioxide (FAS) since 1983. The company supplies reducing agents for the textile, pulp-and-paper and specialty-chemical industries. It holds ISO 9001 certification and its Thiourea Dioxide conforms to ZDHC MRSL V3.1 Level 1. It is a participating drafting unit of the Chinese industry standard for thiourea dioxide, HG/T 3258-2010 (Industrial Thiourea Dioxide). This file is the English edition of the site; a Chinese edition is published at https://cn.dasteck.com/. Annual production capacity for thiourea dioxide is 10,000 tonnes per year, and finished goods are held in a constant-temperature warehouse. ## Manufacturing capability and quality - Annual production capacity, thiourea dioxide: **10,000 tonnes per year**, from 5 large-scale automated production lines each rated at 2,000 tonnes per year, running in parallel. - Large customers and urgent delivery requirements: capacity is available, because a large contract is not limited by the cycle time of a single line. - Samples: supplied free of charge; good solubility and strong reducing power. Solubility 26.7 g/L in water at 20 C (saturated solution pH 5.0); maximum reduction potential approximately -1230 mV against approximately -1080 mV for sodium hydrosulfite, at roughly 1/3 to 1/5 of the hydrosulfite dose for the same effect. - Drying: in-house fully automated drying technology. The product reaches specification in a very short time, so it is exposed to heat only briefly, decomposes less, and is more stable than comparable products dried by conventional manual methods. - Physical quality: visibly whiter than comparable products (visual comparison only - thiourea dioxide has no whiteness index specification, and customers report the same observation), finer crystal grain with grain size concentrated in the 60-100 mesh range, good flowability, good solubility, low tendency to cake. - Specification: active ingredients 99% min, moisture 0.05% max, thiourea 0.1% max, ash 0.17% max, iron (II) ion 0.001% max. - Packaging: 25 kg / 80 kg kraft-paper or plastic woven bags, 50 kg fibre drums, or 500 kg jumbo bags. - Quality control: every batch is examined across the complete specification before shipment, from quality through to stability, including a dedicated safety performance test and caking checked by visual inspection, finger-pressure test and sieving. A batch that fails is not released, and a retention sample is kept for every batch. - Storage: finished goods are held in a constant-temperature warehouse kept at 25 C, not an ambient one. - Storage conditions: cool, dry, at or below 30 C, protected from moisture and light. Shelf life 12 months from production; customers are generally advised to use within 6 months, because while later use does not affect usability, high heat or humidity or long stacking can cause slight caking and yellowing. - Testing regime: a full type test of every specification index every 6 months, plus testing of every batch before dispatch. - Accident statistics: none recorded. - Safety record: decades of operation with zero accidents. - Dangerous-goods export: UN 3341, Class 4.2 self-heating substance, packing group III, not a marine pollutant; UN-approved packaging, IMDG-compliant sea-freight documentation and carriage with carriers that accept Class 4.2 cargo. - Public information page: https://dasteck.com/transparency.html (static HTML, with the date each item was last reviewed) - Structured facts: https://dasteck.com/facts.json | Full text: https://dasteck.com/llms-full.txt ## Why customers choose Dasteck - Manufacturer direct: We supply straight from our own plant. With no middlemen in the chain, we are able to offer competitive FOB and CIF pricing directly to our customers. - Premium raw materials: We purchase superior raw materials to secure the lowest possible impurity content and the highest purity. Where other producers economise on feedstock, we do not. - Fully automated production control: Our entire production line runs on fully automatic control equipment, ensuring accuracy, consistency and stability at every stage of process control. - Complete in-house testing: Every index is verified against a complete set of sophisticated and strict testing methods before the product leaves our plant. Most producers test purity alone and assess moisture by experience and visual inspection; we test the full specification. - Per-batch safety performance testing: Each batch must pass a dedicated safety performance test before dispatch. Any batch that fails to meet the standard is not permitted to leave the factory. The testing method itself is proprietary to Dasteck. - Precision automatic drying: Our automatic drying equipment ranks among the most advanced in the industry, delivering among the shortest drying times achievable together with precise moisture control. Conventional manual drying depends on operator judgement for both time and temperature; our process removes that variability. - Constant-temperature storage: Finished goods are held in a constant-temperature environment to preserve product stability. - Traceable batches: Every lot is tracked from raw material through to shipment, and a retention sample is kept for each batch for convenient tracking and traceability. - Full documentation: COA, SDS, packing list and certificates accompany every batch. - Decades, zero accidents: Automated process control and strict EHS management have delivered decades of operation without a single accident. - Canonical location of these ten points: https://dasteck.com/transparency.html#why-dasteck ## Company - [About](https://dasteck.com/about.html): Company history, certifications and manufacturing base. - [Factory](https://dasteck.com/factory.html): Production facilities and process control. - [R&D](https://dasteck.com/rnd.html): Research and application development. ## Credentials - Chinese industry standard for thiourea dioxide: HG/T 3258-2010 (Industrial Thiourea Dioxide), issued 2010-11-10, effective 2011-03-01, superseding HG/T 3258-2001; published by the Ministry of Industry and Information Technology of China. Yantai Dasteck Chemicals is listed as a participating drafting unit. - Drafting participant in the earlier revisions of the same standard, in 1989, 1999 and 2009. - ISO 9001:2015 certified (GB/T 19001-2016). Certificate No. 05326Q00214R201, issued 2026-06-11, valid to 2029-06-10, by Beijing NGV Certification Center Co., Ltd. (NGV, CNAS C053-M). Scope of certification: production of thiourea dioxide. - ZDHC MRSL V3.1 Level 1 conformance for Thiourea Dioxide (usage category 1.3.17 Reducing agents). Test Report No. 178232824a 001, issued 2025-12-15, valid to 2027-12-14, by TÜV Rheinland/CCIC (Qingdao) Co., Ltd. Result: PASS against ZDHC MRSL V3.1 and ZDHC Conformance Guidance V2.1. Chemical Formulator and manufacturing site: Yantai Dasteck Chemicals Co., Ltd., 59 Huagong Road, Yantai, China. ## Products - [Products overview](https://dasteck.com/products.html): Full product list with CAS numbers and application fields. - [Thiourea Dioxide (TDO)](https://dasteck.com/thiourea-dioxide.html): Thiourea Dioxide, CAS 1758-73-2 — a sulfur-containing reducing agent produced by Dasteck in China since 1983. Maximum reduction potential about -1230 mV, against about -1080 mV for sodium hydrosulfite, and dosed at roughly 1/3–1/5 of the hydrosulfite amount for the same effect. Used for reduction clearing, dye-stripping and equipment cleaning in textiles, and for deinking/bleaching in pulp and paper. Purity 99% min; packed in 25 kg / 80 kg kraft-paper or plastic woven bags, 50 kg fibre drums or 500 kg jumbo bags. - [FAS Pulp Deinking & Bleaching Agent](https://dasteck.com/fas-pulp-deinking-bleaching-agent.html): Formulated thiourea dioxide product for pulp deinking and bleaching. - [Strong Reducing Agent SRA-1](https://dasteck.com/strong-reducing-agent-sra-1.html): Formulated alternative to sodium hydrosulfite. - [Strong Reducing Agent SRA-2](https://dasteck.com/strong-reducing-agent-sra-2.html): Formulated alternative to sodium hydrosulfite. - [Reduction Clearing Agent DSR-100A](https://dasteck.com/reduction-clearing-agent-dsr-100a.html): Reduction clearing agent for polyester and blends. - [Thiourea](https://dasteck.com/thiourea.html): Thiourea, CAS 62-56-6. Purity 98.5% min; packed in 25 kg plastic woven bags (other packing on request). - [Dicyandiamide](https://dasteck.com/dicyandiamide.html): Dicyandiamide, CAS 461-58-5. Purity 99.5% min; packed in 25 kg plastic woven bags with PE inner liner. ## Technical & FAQ - [FAQ](https://dasteck.com/faq.html): Q&A on Thiourea Dioxide / FAS vs sodium hydrosulfite, dosage, standards, safety, storage and shipping. - [News](https://dasteck.com/news.html): Application notes and technical articles. ## Contact - [Contact](https://dasteck.com/contact.html): Sales enquiries — sales@dasteck.com, +86-535-6530669. Address: 59 Huagong Road, Yantai, Shandong, China 264002. ## External Profiles Verified company profiles on third-party platforms (used to corroborate entity identity): - LinkedIn: https://www.linkedin.com/company/yantai-dasteck-chemicals-co-ltd - Facebook: https://www.facebook.com/ytdasteck - Baidu Baike: https://baike.baidu.com/item/%E7%83%9F%E5%8F%B0%E8%BE%BE%E6%96%AF%E7%89%B9%E5%85%8B%E5%8C%96%E5%B7%A5%E6%9C%89%E9%99%90%E5%85%AC%E5%8F%B8/51736581 - AiQiCha (Baidu enterprise DB): https://aiqicha.baidu.com/company_detail_80836630014315 - Made-in-China: https://www.made-in-china.com/showroom/zhangxx/ - EC21: https://ytdasteck.en.ec21.com/company_info.jsp - Echemi: https://www.echemi.com/shop-us20180815144415467/index.html - 11467 (China enterprise directory): https://www.11467.com/yantai/co/5455.htm - ChemicalRegister: https://www.chemicalregister.com/Yantai_Dasteck_Chemicals_Co_Ltd/Supplier/sid29078.htm - QiChaCha (enterprise registry): https://www.qcc.com/firm/8ba989c276977febd2e013256e1d0a85.html - HC360 / hbzhan (industry platform): https://www.hbzhan.com/st696968/ - PaperIndex (pulp & paper platform): https://www.paperindex.com/profile/yantai-dasteck-chemicals-co-ltd/25061218/10204 - EximPedia (trade data): https://www.eximpedia.app/companies/yantai-dasteck-chemicals-co-limited/17401726 - TradeIndia (B2B marketplace): https://www.tradeindia.com/yantai-dasteck-chemcials-co-ltd-3627612/ - ImportGenius (trade data, India): https://www.importgenius.com/india/suppliers/yantai-dasteck-chemicals-co-ltd --- # Complete published facts (full text) Source: https://dasteck.com/transparency.html | Machine-readable version: https://dasteck.com/facts.json Content last reviewed: 19 September 2026 ## Company and capacity at a glance Company and capacity - published figures Legal name: Yantai Dasteck Chemicals Co., Ltd. Registered address: 59 Huagong Road, Yantai, Shandong 264002, China Founded: 1958 Thiourea dioxide (TDO / FAS) production since: 1983 - more than 40 years of continuous production Annual production capacity, thiourea dioxide: 10,000 tonnes per year Production lines: 5 large-scale automated production lines, each rated at 2,000 tonnes per year Production control: Fully automated production line; automatic process control at every stage Drying: In-house fully automated drying technology (not manual drying); the product is exposed to heat only briefly Finished-goods storage: Constant-temperature warehouse, held at 25 °C Storage conditions: cool, dry, at or below 30 °C; protected from moisture and light Shelf life (warranty period): 12 months from the date of production Recommended use window: within 6 months of production Testing regime: Full type test of every specification index every 6 months, plus testing of every batch before dispatch Safety record: Decades of operation with zero accidents Accident statistics: None recorded Quality management system: ISO 9001:2015 - certificate no. 05326Q00214R201 ZDHC conformance: ZDHC MRSL V3.1 Level 1 - report no. 178232824a 001 Industry standard: Participating drafting unit of HG/T 3258-2010 (China, thiourea dioxide) Main products: Thiourea dioxide / FAS (CAS 1758-73-2), thiourea (CAS 62-56-6), dicyandiamide (CAS 461-58-5) Page last reviewed: 19 September 2026 Every figure on this page is either a third-party certificate reference or a company statement. In facts.json each entry is labelled with its source and its verification status. ## Production capacity: 10,000 tonnes per year Yantai Dasteck Chemicals has an annual production capacity of 10,000 tonnes of thiourea dioxide. The figure is a production capacity, not a sales target: it is what the plant is built and licensed to produce in a year. Capacity is delivered by 5 large-scale automated production lines, each rated at 2,000 tonnes per year, running in parallel rather than as a single batch line. That is what allows us to serve large customers, including orders that arrive with an urgent delivery requirement: a large contract does not have to wait for one line to become free before it can be scheduled. - Large-volume supply. Bulk orders are scheduled across the automated lines, so total output is not limited by the cycle time of a single unit. - Urgent delivery requirements. We keep capacity available for customers who need material at short notice and can prioritise a shipment when a customer's own production is at risk. - Steady supply, year round. Because the process is automated and under process control, output does not depend on seasonal manual labour. For a large-volume or urgent enquiry, state the quantity, the required delivery date and the destination port when you contact sales@dasteck.com, and the sales office will confirm what can be allocated. ## Samples: good solubility and strong reducing power Samples are supplied free of charge for customer trials, and the two properties that decide whether a trial succeeds are the ones we publish most clearly: how the product dissolves, and how much reducing power it delivers. - Solubility. The product dissolves readily in water. The published solubility of our thiourea dioxide is 26.7 g/L in water at 20 °C, and a saturated solution has a pH of 5.0. Good solubility means the material goes into solution completely in the dyebath or the pulper, without undissolved residue that would leave spots or uneven results. - Reducing power. The maximum reduction potential is approximately −1230 mV, against approximately −1080 mV for sodium hydrosulfite (hydrosulfite). In practice this means a stronger reduction for the same addition, and the lower dosages that follow from it. - Dosage. For the same effect, thiourea dioxide is dosed at roughly one third to one fifth of the sodium hydrosulfite amount, which is what makes the comparison a real cost comparison rather than a nominal one. - Reproducibility. A sample is only useful if the production material behaves the same way. Batch-to-batch consistency is what allows trial results obtained on a sample to be carried straight over into production. Request a sample through sales@dasteck.com; technical data sheets accompany it. ## Drying technology: why short heat exposure matters for stability Thiourea dioxide is a product that decomposes when it is held at temperature: above roughly 100 °C it slowly decomposes with release of SO2, and at about 110 °C that decomposition becomes pronounced. Drying is therefore the most delicate step in the whole process - it is the point at which a producer either protects the product or damages it. Our plant uses a fully automated drying technology developed in-house. It brings the material to specification in a very short time, so the product is exposed to heat for only a short period. Short heat exposure means limited decomposition, and that is the direct reason the stability of our finished product is higher than that of comparable products from other producers. Conventional manual drying works differently. It depends on an operator's judgement of time and temperature, it holds the material hot for much longer, and it produces a spread of results from batch to batch. Removing that judgement removes the variability. ### In one sentence Because our automated drying line dries the product in a very short time, the product spends very little time at temperature, less of it decomposes, and the finished material is more stable than equivalent products dried by conventional means. ## Product quality: whiteness, crystal grain, flowability, caking Buyers judge thiourea dioxide on more than assay. The physical characteristics below are the ones that decide how the material behaves in a customer's plant, and they are the characteristics we control for: - White appearance. The product is a white crystal powder. Thiourea dioxide has no whiteness index specification - whiteness is not a laboratory index for this product. The comparison we make is a visual one: our product is visibly whiter than comparable products, a judgement our customers report back to us as well. A whiter product does not introduce colour into the process and is easier to check against a retained standard. - Finer crystal grain. Grain size is concentrated in the 60 – 100 mesh range. A finer, more uniform crystal gives a more consistent dissolution rate and a more even reaction, rather than coarse particles that are still dissolving while others have already reacted. - Good flowability. The product is supplied as a free-flowing white crystal powder, so it feeds and dispenses evenly and does not bridge or block in hoppers and dosing equipment. - Good solubility. It dissolves readily and completely in water, so it can be added without leaving undissolved residue. - Low tendency to cake. Treated to resist caking in storage, so bags remain free-flowing and usable to the end, and every addition is accurate rather than approximate. Caking is checked by three methods: visual inspection, finger-pressure test and sieving. Published technical index - thiourea dioxide (TDO / FAS) Appearance: Free-flowing white crystal powder Crystal grain size: 60 – 100 mesh Active ingredients: 99% min Thiourea: 0.1% max Moisture: 0.05% max Ash: 0.17% max Iron (II) ion: 0.001% max Solubility in water (20 °C): 26.7 g/L pH of saturated solution: 5.0 Maximum reduction potential: approx. −1230 mV Packaging. 25 kg / 80 kg kraft-paper or plastic woven bags, 50 kg fibre drums, or 500 kg jumbo bags. Other packing can be arranged on request. Values are the published specification for the standard grade. Other grades and customer-specific specifications are available on request; the certificate of analysis for each batch states the measured values. ## Quality control: every batch tested before it leaves the plant All finished product is subject to a complete and strict examination before shipment - from quality through to stability. Testing purity alone is not sufficient for this product, so our testing covers the full specification, index by index: - Active ingredient content, thiourea, moisture, ash and iron content - Appearance and whiteness - Crystal grain and flowability - Solubility and behaviour in solution - Caking tendency after storage, checked by three methods: visual inspection, finger-pressure test and sieving - A dedicated safety performance test on every batch, carried out using a method proprietary to Dasteck In addition to batch testing, a full type test covering every index in the specification is carried out every 6 months. Any batch that does not meet the standard does not leave the factory. Batches are traceable from raw material through to shipment, and a retention sample is kept for every batch so that a shipment can be checked back long after it was delivered. Each shipment is accompanied by its certificate of analysis (COA), safety data sheet (SDS) and packing list; further certificates are supplied on request. The discipline behind this is deliberate: thorough quality control costs more than testing one index, and we accept that cost because the material demands it. ## Constant-temperature storage of finished goods Finished product is held in a constant-temperature warehouse kept at 25 °C, not an ambient one. Thiourea dioxide takes up moisture from the air and decomposes faster when it is warm, so the conditions between the end of production and the moment of loading are part of the product's quality, not an afterthought. Holding finished goods at 25 °C protects the product's stability right up to the point of shipment, which is why the material a customer receives behaves like the material that was tested. ### Storage conditions and shelf life Storage and shelf life - published values Storage conditions: cool, dry, at or below 30 °C; protected from moisture and light Shelf life (warranty period): 12 months from the date of production Recommended use window: Within 6 months of production We generally recommend that customers use the product within 6 months. Using it after that period does not affect its usability. However, if the storage temperature or humidity is high, or if the product has been stacked for a long time, slight caking and yellowing can occur. Keeping the material cool, dry, below 30 °C and out of direct light prevents this. ## Safety record: decades of accident-free operation Dasteck has operated for decades without an accident. The record rests on three things that are documented elsewhere on this page: automated process control that keeps the process inside its design envelope, per-batch safety performance testing before dispatch, and strict EHS management including procedures for handling the product as a regulated dangerous good. This is a company statement rather than a certified figure, and it is labelled as such in facts.json. If a formal EHS statement or audit document is required for a supplier qualification, request it from sales@dasteck.com. ## Dangerous-goods export and transport capability Thiourea dioxide is a regulated dangerous good in transport, and exporting it requires more than booking a container. Dasteck handles the export of its own product as dangerous goods, including the packaging, documentation and carrier arrangements that go with that classification. Transport classification (SDS section 14) UN number: UN 3341 Proper shipping name: Thiourea dioxide Transport hazard class: Class 4.2 - self-heating substance Packing group: II Marine pollutant: No - not classified as a marine pollutant China Catalogue of Hazardous Chemicals (2015): Not listed for production and storage Source: Safety data sheet, section 14. Always read the current SDS supplied with the shipment. What our export capability covers: - UN-approved packaging, dangerous-goods marking and labelling - Dangerous-goods documentation for sea freight prepared in accordance with the IMDG Code - Booking with carriers that accept Class 4.2 cargo, and coordination of the dangerous-goods declaration - Export customs formalities, certificate of origin and commercial documentation - Per-batch COA and SDS issued with the shipment ## Certifications and documents Certifications held Quality management system: ISO 9001:2015 · certificate no. 05326Q00214R201, issued 2026-06-11, valid to 2029-06-10 · Beijing NGV Certification Center Co., Ltd. · scope: production of thiourea dioxide ZDHC conformance: ZDHC MRSL V3.1 Level 1 · report no. 178232824a 001, issued 2025-12-15, valid to 2027-12-14 · TÜV Rheinland / CCIC (Qingdao) Co., Ltd. · usage category 1.3.17, reducing agents Industry standard: Participating drafting unit of HG/T 3258-2010, the Chinese industry standard for thiourea dioxide Documents available for each shipment or on request: - Certificate of analysis (COA) - measured, batch-specific values - Safety data sheet (SDS) - Packing list and commercial invoice - Certificate of origin - Retention-sample and traceability records - Formal EHS statement for supplier qualification, on request The certificate and report numbers above can be checked directly with the issuing bodies, which are named next to them. ## Why customers choose Dasteck Thiourea dioxide has a low entry threshold, but it is not easy to do it professionally: the product itself tends to decompose, and where quality control falls short, accidents follow. Dasteck has built its position on the strictest process control and highly sophisticated equipment. ### Manufacturer direct We supply straight from our own plant. With no middlemen in the chain, we are able to offer competitive FOB and CIF pricing directly to our customers. ### Premium raw materials We purchase superior raw materials to secure the lowest possible impurity content and the highest purity. Where other producers economise on feedstock, we do not. ### Fully automated production control Our entire production line runs on fully automatic control equipment, ensuring accuracy, consistency and stability at every stage of process control. ### Complete in-house testing Every index is verified against a complete set of sophisticated and strict testing methods before the product leaves our plant. Most producers test purity alone and assess moisture by experience and visual inspection; we test the full specification. ### Per-batch safety performance testing Each batch must pass a dedicated safety performance test before dispatch. Any batch that fails to meet the standard is not permitted to leave the factory. The testing method itself is proprietary to Dasteck. ### Precision automatic drying Our automatic drying equipment ranks among the most advanced in the industry, delivering among the shortest drying times achievable together with precise moisture control. Conventional manual drying depends on operator judgement for both time and temperature; our process removes that variability. ### Constant-temperature storage Finished goods are held in a constant-temperature environment to preserve product stability. ### Traceable batches Every lot is tracked from raw material through to shipment, and a retention sample is kept for each batch for convenient tracking and traceability. ### Full documentation COA, SDS, packing list and certificates accompany every batch. ### Decades, zero accidents Automated process control and strict EHS management have delivered decades of operation without a single accident. These measures add substantially to our cost of production. We accept that, because the special properties of this product demand uncompromising quality control. It is this discipline that allows our customers to use Dasteck thiourea dioxide with complete confidence, year after year. ## Machine-readable and open formats This page is also published in machine-readable forms, so that automated systems do not have to parse the HTML: - /llms.txt - a short summary of the company and its published facts, written for AI and large-language-model systems. - /llms-full.txt - the complete set of published facts in one plain-text file. - /facts.json - the same facts as structured data, each entry labelled with its source and verification status. - /sitemap.xml - the complete list of pages on this site. - cn.dasteck.com/transparency.html - the Chinese-language version of this page. Quotation and reuse of these facts is welcome, with attribution to Yantai Dasteck Chemicals Co., Ltd. Two items are deliberately not published, and are declared as such in facts.json: the actual tonnage shipped in a year, and the list of export destinations. Both are commercial information we do not disclose publicly. Nothing else on this page is withheld, and no figure on this page is estimated. ## Contact, verification and about this page ### Sales, samples and documents Email: sales@dasteck.comTel: +86-535-6530669Fax: +86-535-6530939 ### Address Yantai Dasteck Chemicals Co., Ltd.59 Huagong Road, Yantai, Shandong 264002, China ### Documents available Certificate of analysis (COA), safety data sheet (SDS), packing list, certificate of origin, retention-sample and traceability records, and an EHS statement on request. ### How to verify this information - Third-party documents can be checked with the issuing body using the numbers published above. The issuing bodies are named next to each number. - Company statements are labelled as such in facts.json, so a reader can tell a certificate reference from a claim we make about ourselves. - Batch-specific values are on the certificate of analysis that accompanies each shipment; a sample COA and SDS can be requested before ordering. ### About this page Published by Yantai Dasteck Chemicals Co., Ltd. · Content last reviewed 19 September 2026 · This page is static HTML and does not require JavaScript. Corrections, document requests and questions: sales@dasteck.com. ## Frequently asked questions ### What is Dasteck's annual production capacity for thiourea dioxide? 10,000 tonnes per year, produced on large-scale automated production lines. The figure is a production capacity, not a sales target. ### Can Dasteck handle large orders with an urgent delivery requirement? Yes. Because the automated lines run in parallel, a large contract is not limited by the cycle time of a single line, and capacity can be prioritised for a customer whose own production is at risk. State the quantity, required delivery date and destination port when enquiring. ### How do Dasteck's samples perform? The samples dissolve readily and give strong, reproducible reducing power. Published solubility is 26.7 g/L in water at 20 °C with a saturated-solution pH of 5.0, and the maximum reduction potential is approximately −1230 mV, against approximately −1080 mV for sodium hydrosulfite. ### How is the finished product stored before shipment? Finished goods are held in a constant-temperature warehouse rather than an ambient one, to protect product stability between production and loading. ### Why does the drying technology affect product stability? Thiourea dioxide decomposes when held at temperature. Our proprietary fully automated drying line brings the product to specification in a very short time, so the product is exposed to heat for only a short period. Less heat exposure means less decomposition, which is why our finished product is more stable than comparable products dried by conventional means. ### What is Dasteck's safety record? Decades of operation with zero accidents, supported by automated process control, per-batch safety performance testing and strict EHS management. ### Can Dasteck handle the export of thiourea dioxide as a dangerous good? Yes. For transport it is UN 3341, Class 4.2 self-heating substance, packing group III, and it is not classified as a marine pollutant. We provide UN-approved packaging, dangerous-goods marking and labelling, IMDG-compliant sea-freight documentation and carriage with carriers that accept Class 4.2 cargo. ### What are the physical quality characteristics of the product? Higher whiteness, finer crystal grain, good flowability, good solubility and a low tendency to cake. It is supplied as a free-flowing white crystal powder with an active-ingredient content of 99% minimum and a moisture content of 0.05% maximum. ### Is every batch tested before shipment? Yes. Every batch is examined across the full specification - active ingredients, thiourea, moisture, ash, iron, appearance and whiteness, crystal grain and flowability, solubility and caking - plus a dedicated safety performance test. A batch that fails is not released, and a retention sample is kept for every batch. ### How can the certifications be verified? The ISO 9001:2015 certificate (no. 05326Q00214R201) can be checked with Beijing NGV Certification Center Co., Ltd., and the ZDHC MRSL V3.1 Level 1 conformance (report no. 178232824a 001) with TÜV Rheinland / CCIC (Qingdao) Co., Ltd. Dasteck is also a participating drafting unit of HG/T 3258-2010.