Summary of Findings

Four conditions account for most arrival disputes, and they do not have the same cause or the same consequence. Caking and binder separation can reflect temperature exposure during transit or storage, alongside formulation, production and packing factors. Powdering is mechanical and may originate before dispatch or during handling; arrival evidence and retained samples are needed to distinguish them. Package damage is mechanical too, but its significance lies in what it admits rather than in the damage itself.

The temperature mechanism is easier to reach than most receiving procedures assume. At an external temperature of approximately 25 °C, the air temperature inside a brown-painted container rises to approximately 50 °C, against approximately 38 °C in a white-painted one, and overheating relative to the external air may be considerable even under normal weather conditions (Transport Information Service, GDV). Binder softening points reported across suppliers span 53–75 °C (Wilkinson et al., Infacon IX). On a summer or tropical routing the margin between the two is small, and it is smallest at the top of the stack, since the roof is where solar radiation and heat exchange are strongest.

Key Findings

• Transit and handling can contribute to all four conditions. Only package damage is visible without opening, and it is the least informative of the four about the material.
• Container air temperature is not ambient temperature. A dark container at 25 °C outside reaches about 50 °C inside (TIS, GDV) — within reach of the lower end of the reported binder softening range.
• The cargo lags the air. Variations in the temperature of the cargo inside a container are less marked than those of the air (TIS, GDV), so an air-temperature peak does not transfer fully to the paste. This is why caking is common and severe caking is not.
• Powdering requires handling-route evidence. A consignment arriving sound can still present as a fines problem after several transfers, which is why the assessment point has to be specified before it matters.
• Only binder separation changes the material locally. Caking changes the form, powdering changes the size distribution, package damage changes exposure; separation changes composition where it occurs.

Contents

1. What do the four conditions look like?
2. What causes each one?
3. What evidence should be collected on arrival?
4. Which conditions affect usability, and which do not?
5. How is a claim handled?
6. Frequently asked questions
7. Related reading

1. What Do the Four Conditions Look Like?

Classification before diagnosis. The four present differently, and misclassifying one as another sends the investigation to the wrong party.

Condition	Appearance on opening	Where it is worst	What it indicates
Caking	Blocks adhering to one another or to the bag liner; the mass parts along block faces when disturbed	Upper layers of the stack; containers with dark exteriors	Elevated temperature during transit or storage, with stack compaction
Powdering	Loose fine material at the base of the bag and against the liner; dust on opening	Lower layers; consignments with more handling transfers	Mechanical breakdown across the handling route
Binder separation	Glossy, tacky binder-rich material at one surface with a duller, aggregate-rich region adjacent	Upper layers and against the container wall	Binder mobility at elevated temperature over an extended period
Package damage	Torn fabric, failed lifting loops, deformed or collapsed bags, wet marks	Anywhere; often at the door end or where stowage shifted	Mechanical event in handling or stowage, or water ingress

Table 1. The four are distinguished on opening rather than from the outside; package damage is the only one visible before the bag is opened, and it is the least informative about the material inside.

Two of these are frequently reported together and should not be conflated. Caking with binder separation at the same surface indicates a sustained thermal exposure; caking without separation is more usually compaction under stack load with a modest thermal contribution.

2. What Causes Each One?

Caking and binder separation — the thermal route. Both follow from binder mobility, and the temperatures involved are reached more easily than the ambient record suggests. The Transport Information Service records that at an external temperature of approximately 25 °C, air inside a brown-painted container rises to approximately 50 °C, while a white-painted container reaches approximately 38 °C; overheating of the internal air relative to the external air may be considerable even under normal weather conditions, and the roof is where solar radiation and heat exchange are strongest.

Set against binder softening points spanning 53–75 °C (Wilkinson et al., Infacon IX), the margin on a summer or tropical routing is small, and smallest at the top of the stack. Two qualifications keep this from being read as an inevitability. First, the cargo temperature lags: variations in the temperature of the cargo inside a container are less marked than those of the air (TIS, GDV), so a short air-temperature peak does not transfer fully into the paste. Second, softening point is a transition rather than a threshold — material below it is not entirely immobile, and material near it does not liquefy.

Stack load acts with temperature rather than independently. Compaction under the weight of upper layers brings block faces into closer contact, which is why caking concentrates where thermal exposure and stack load coincide.

Powdering — the mechanical route. Every transfer between discharge and the charging platform breaks some material, and the quantity depends on block form, packing and the number of transfers rather than on the voyage. This route is treated in the block shape article, which also sets out why fines behave as a separate material once generated. A consignment that arrives sound can still present as a fines problem at the furnace.

Package damage — the mechanical route, with a consequence. The damage itself is a handling or stowage event. Its significance is what it admits: moisture changes the mass basis on which every other parameter was reported, which is why a wet-marked bag is a documentation question before it is a material question.

3. What Evidence Should Be Collected on Arrival?

Before unloading proceeds beyond the first bags, and while the container is still identifiable:

1. Container identity and stowage position, with the seal number and its condition.
2. Photographs of the load in place, before any bag is moved, then of the first opened bag from two angles.
3. Position within the stack for any bag showing caking or separation — upper, middle or lower layer, and whether against a wall or the door end.
4. Voyage route and dates, and the transhipment points if known. This is what makes the thermal exposure assessable rather than speculative.
5. Container exterior colour and condition, which is a real variable given the difference between the brown and white cases recorded by TIS.
6. Weighed fines, from a defined quantity of material rather than an impression.
7. A retained sample from the affected bags and from an unaffected bag in the same consignment.

Items 3 to 5 are the ones usually omitted, and they are the ones that distinguish a thermal explanation from a production explanation. A consignment where caking is confined to the upper layers of a dark container on a summer routing has a mechanism attached to it; the same caking distributed evenly through the load does not, and points elsewhere.

The documentation, certificate applications, inspection records and shipping arrangements for each consignment are coordinated by the export coordinator, and the container and voyage details in items 1 and 4 can be supplied from the shipping file if they were not recorded on arrival.

4. Which Conditions Affect Usability, and Which Do Not?

Caking. Usually a handling problem rather than a material problem. Where the mass parts along block faces and the individual blocks are intact, the composition is unchanged and the parameters on the Certificate of Analysis (COA) still describe it. The operational consequence is at the charging platform — caked material charges unevenly and can contribute to the void structure discussed in the bridging article.

Powdering. Changes the size distribution reaching the melt, not the composition of the batch. Fines segregate rather than distributing evenly, so the material at the melt differs from the batch as tested, and no parameter on the report captures this. Whether it affects usability depends on the proportion and on the furnace.

Binder separation. The one condition that changes the material locally. Where binder has migrated, the binder-rich and aggregate-rich regions no longer match the formulation, and volatile matter and softening point in that material differ from the values reported for the batch. Affected material should be segregated and sampled rather than charged.

Package damage. Significant to the extent that it admitted moisture or contamination. A torn bag with dry, clean material inside is a packaging claim; a wet-marked bag is a material question, because moisture alters the basis on which the other parameters were reported — the basis question treated in the report consistency article.

5. How Is a Claim Handled?

A claim on arrival condition succeeds or fails on three things that must exist before the claim is made.

A stated limit and a stated assessment point. A fines claim without a contractual limit and without a defined point of assessment — at the port of loading, at the port of discharge, or at the plant after unloading — has no factual basis on either side. These belong in the purchase specification, and the enquiry article sets out where.

Arrival evidence. The seven items in Section 3, collected before unloading proceeded. Evidence collected after the load has been broken down cannot establish stack position, and stack position is what distinguishes a thermal mechanism from a production one.

Retained samples at both ends. Retained material converts a disagreement into a re-test. Where neither party holds one, the discussion moves from technical to commercial, and the outcome follows the commercial relationship rather than the evidence.

The sequence that follows is: notify with the evidence attached and the specific condition identified; agree whether the affected material is segregated or charged; and where the material is questioned rather than the packaging, re-test the retained sample against the batch COA. Where the two disagree, the sampling and method questions treated in the standards article apply before any conclusion about the batch.

6. Frequently Asked Questions

Q1. The upper bags are caked and the lower ones are not. Is this a production problem? The distribution supports checking transit exposure first, but does not exclude production or packing differences. Thermal exposure is often greatest at the top — the roof is where solar radiation and heat exchange are strongest (TIS, GDV). Record the stack positions, the container exterior colour and the voyage route before raising it with the supplier, since those three establish whether a thermal mechanism is available.

Q2. Caked material breaks apart into intact blocks. Can it be charged? Where the blocks are intact and no binder separation is present, the composition is unchanged and the COA still describes it. The practical question is charging: caked material charges unevenly and can contribute to voids and bridging above the melt. Break it down to individual blocks before charging rather than charging the mass.

Q3. How much fines is acceptable on arrival? That is a contractual figure, not a standard one, and it has to be agreed with the assessment point stated. No general value exists, because the acceptable proportion depends on the block form and on the number of handling transfers between discharge and the charging platform. Set it in the purchase specification before the first shipment.

Q4. A bag shows wet marks. What should be done before charging? Segregate it and sample it, rather than charging it or rejecting it on sight. Moisture changes the mass basis on which every other parameter was reported, so the useful step is a moisture determination on the affected material compared with an unaffected bag from the same consignment. Whether the material is usable follows from that, not from the appearance of the bag.

Q5. Can arrival condition be improved by specification rather than by claim? Yes, and this is the more productive route. Packing type and capacity, stacking height, weather protection, container colour where it can be influenced, and the assumed storage conditions at destination all belong in the purchase specification. Specifying them is what makes a later condition assessable; specifying none of them leaves every arrival dispute without a reference.

7. Related Reading

• Paste Column Bridging and Uneven Sintering (companion article) — where caked and uneven material reaches next
• Paste Block Shape and Size: How Geometry Affects Feeding and Sintering — why fines are generated rather than delivered, and how they behave once generated
• Electrode Paste Packaging and Storage for Export Orders — the packing and storage conditions this article assesses against
• Matching Softening Point to Furnace Operating Rhythm — the binder property behind the thermal route
• Reading a Seven-Parameter Test Report for Internal Consistency — the moisture basis question raised by package damage
• What a Complete Technical Enquiry for Electrode Paste Should Contain — where the fines limit and assessment point are specified

Author and Review

Written by Sterling Yang, Senior Vice President at Jiyang Carbon.

This article was reviewed by Mr. Yang, Technical Director at Jiyang Carbon, drawing on 40+ years of hands-on experience in carbon processing. The documentation and claim evidence in Sections 3 and 5 were reviewed by Stella, Export Coordinator, who coordinates packing lists, commercial documents, certificate applications, inspection records and shipping arrangements.

Container climate values are taken from the Transport Information Service published by the German Insurance Association, cited in this article; the binder softening point range is from the published source also cited above. No acceptable fines proportion is given, because that is a contractual figure agreed per plant and per handling route. Jiyang Carbon packs export consignments in one-tonne bulk bags, ships to more than twenty countries, and issues a Certificate of Analysis traceable to the batch with every consignment.

Technical Consultation

For assistance in assessing an arrival condition, or in setting packing and condition clauses before a first shipment, please contact the team.

Get a Technical Consultation →