How To Best Prepare Your Sample for Testing

Whether you’re evaluating aggregates, minerals, coal or industrial byproducts, laboratory testing is a critical step in determining the right processing equipment for your material. Before any analysis can begin, the quality and condition of your sample play a pivotal role in the accuracy and usefulness of the test results. Poorly prepared samples can result in misleading data, incorrect equipment recommendations and costly delays. 

This guide explores the best practices for preparing your sample for testing, ensuring that your material arrives at the lab in optimal condition and yields reliable, actionable results. 

Before you even begin collecting your sample, it’s essential to understand why the material is being tested. Labs typically analyze samples to determine:

• Particle size distribution
• Moisture content
• Abrasiveness
• Hardness
• Density
• Chemical composition
• Flowability
• Crushability or grindability
   

Knowing which properties are being evaluated helps you tailor your sample preparation accordingly. For example, if the lab is testing for moisture content, you’ll need to take extra care to preserve the sample’s natural moisture levels during transport. 

One of the most common issues in material testing is submitting a sample that does not accurately represent the full bulk of material. A representative sample ensures that the lab’s findings reflect the true characteristics of the material and not just a localized portion. 

Tips for collecting an accurate representative sample: 

• Sample from multiple locations: If the material is stored in a pile, bin or silo, take samples from the top, middle and bottom. Sampling devices, such as zone samplers or probes, may be used to easily collect a representative sample.
• Avoid segregation: Fine and coarse particles tend to separate during handling. Mix the material thoroughly before sampling.
• Use proper sampling tools: Shovels, scoops or augers should be clean and appropriate for the material type.
• Follow industry standards: Refer to ASTM, ISO or other relevant standards for the sampling procedures specific to the material being tested. 

Collecting the correct sample size is one of the most overlooked but critical steps in preparing for lab testing. Labs typically require a minimum amount of material to perform accurate and comprehensive analyses. However, sending too much material can be inefficient and costly. The ideal sample size depends on several factors:

• Type of testing: Particle size distribution, moisture content, durability and other tests each have unique sample volume requirements.
• Material characteristics: Heterogeneous materials may require larger samples to ensure representativeness, while homogeneous materials might need less.
• Number of tests: The more tests being conducted, the more material the lab will need to divide and allocate across procedures.

Always consult with the lab before sending samples. Ask for their recommended sample size for each test and clarify whether they need separate samples for different analyses or if a composite sample will suffice. Some labs provide sample size guidelines or worksheets to help streamline this process. 

Contamination can skew test results and lead to incorrect conclusions. To avoid this:

• Use clean containers: Buckets, bags or jars should be free of residues such as dust or oil.
• Avoid cross-contamination: If sampling multiple materials, use separate tools and containers for each.
• Seal the sample: Use airtight bags or containers to prevent exposure to moisture, air or foreign particles.
• Label everything clearly: Include the material name, source location, date of collection and any relevant notes.

Many material properties can change during transport, especially moisture content, flowability and particle cohesion. To preserve the sample’s natural state:

• Keep it cool: If the material is sensitive to heat, store it in a temperature-controlled environment.
• Avoid drying out: Use sealed plastic bags or moisture-retaining containers for wet or damp samples.
• Prevent compaction: Don’t overfill containers, as this can compress the material and alter its structure.

Proper packaging ensures your sample arrives at the lab intact and ready for testing. Here are some packaging tips:

• Use sturdy containers: Heavy-duty plastic buckets, drums or reinforced bags are ideal for bulk samples.
• Double-bag fine materials: Powders or fine particles can leak during transit. Double-bagging helps prevent loss.
• Cushion fragile materials: If your sample includes friable or brittle particles, pad the container to prevent breakage.
• Label with care: Include your contact information, material description and any handling instructions.

Labs rely on context to interpret test results accurately. Always include:

•    Material description: Type, source and any known properties.
•    Intended use: What process or equipment you’re evaluating.
•    Testing goals: Specific properties or behaviors you want analyzed.
•    Safety data: MSDS sheets or hazard warnings if applicable.

A well-documented sample helps the lab tailor its testing approach and deliver more relevant recommendations.

Before sending your sample, reach out to the testing lab to confirm sample requirements, discuss testing objectives and clarify any special handling needs. Open communication ensures your sample preparation aligns with the lab’s expectations and avoids unnecessary delays.

Before shipping your sample to the lab, run through this quick checklist: 

• Sample is representative of the bulk material
• Quantity meets lab requirements
• Material is uncontaminated and sealed
• Packaging is secure and properly labeled
• Documentation is complete
• Lab has been contacted