Sample Bag Guide: Cloth, Poly, Canvas and Kraft for Soil, Chips and Core
The short answer
Match the bag to the sample and to what happens to it next. Dry rock chips and RC cuttings going to a lab: a Protexo cloth bag. Samples that will be oven-dried: Heavy Sentry polyester with the heat-resistant barcode tag. Wet or fine samples that need to drain: Nano-Por. Anything that touches acid or solvents, or is heated past 325 F: Micro-Por PE. Soil for geochemistry: kraft tin-tie envelopes or a small Protexo bag. Fines, water or anything that must not leak: polyethylene, seal-top or 4 to 8 mil. Bulk samples: Super Sacks. If you are not sure, the Protexo 12 x 18 in bag is the one most exploration crews order for a standard RC or rock chip sample.
Which bag for which sample
| Sample | Bag to use | Why |
|---|---|---|
| RC chips and rock chips to the lab | CGS Protexo (poly-cotton cloth) | Breathes so damp chips dry out, lowest-cost cloth bag per sample, takes a marker and a tag |
| Rock chips, heavy or sharp | CGS Heavy Protexo (heavy 100% cotton) | Thicker cotton for abrasive material and long hauls |
| Samples that will be oven-dried | CGS Heavy Sentry (polyester) | Polyester and a heat-resistant barcode tag rated to 325 F, unique bag number on every bag |
| Wet samples, sludge, anything that must drain | CGS Nano-Por (acrylic-coated polyester) | The coating gives filtration and drainage without losing fines |
| Samples heated above 325 F, acid or solvent contact | Micro-Por PE (polyethylene) | Inert to most organic chemicals, acids, bases and salts; rated to 400 F |
| Soil for geochemistry, small volume | Kraft soil sample envelopes, tin tie | Writes on, the tin tie holds, 3 x 5 in up to 5 x 9 in |
| Soil or chips that must stay sealed | Polyethylene bags, 4, 6 or 8 mil, or seal-top PE | Holds fines and water; 8 mil for sharp chips |
| Core pieces, metallurgical or bulk splits | Heavy Protexo core bags, 10 x 17 in and up | Room for core lengths, cotton takes the weight |
| Bulk samples, hundreds of pounds | CGS Super Sack, coated sift-proof or uncoated polypropylene | 4,000 lb (coated) and 3,000 lb (uncoated) safe working load, forklift loops |
| Shipping bagged samples | Transport bags, woven polypropylene | 18 x 30 in and 24 x 36 in |
Fabric comparison
| Protexo | Heavy Protexo | Heavy Sentry | Nano-Por | Micro-Por PE | Canvas | |
|---|---|---|---|---|---|---|
| Fabric | 50/50 poly-cotton | Heavy unfinished 100% cotton | Polyester | Polyester, acrylic coated | Polyethylene | Cotton canvas |
| Breathes or drains | Yes | Yes | Yes | Yes, drains | No | Yes |
| Heat rating | To 250 F | To 250 F | To 325 F (tag) | Not rated | To 400 F | To 250 F |
| Chemical resistance | Normal | Normal | Normal | Normal | Acids, bases, salts, most organics | Normal |
| Closure | Drawstring | Drawstring | Drawstring | Drawstring | Drawstring or wrap-tie | Wrap-tie or draw cord |
| Tag | 2 x 3 in waterproof yellow, double-sided | Same | Heat-resistant barcode tag, unique number | Same as Protexo | Same as Protexo | Same as Protexo |
| Sizes | 10, 3.5 x 5 to 20 x 24 in | 7, 5 x 8.5 to 20 x 24 in | 9, 3.5 x 5 to 20 x 24 in | 5, 11 x 17 to 19 x 22 in | 4, 11 x 17 to 19 x 22 in | 6, 6 x 11 to 17 x 28 in |
| Sold as | Box of 100 | Box of 100 | Box of 100 | Box of 100 | Box of 100 | Box of 25 |
Size guide
Sizes are flat width by length in inches. The same sizes run across Protexo, Heavy Protexo and Heavy Sentry, so you can change fabric without changing your sample size.
| Size | Protexo | Heavy Protexo | Heavy Sentry | Typical use |
|---|---|---|---|---|
| 3.5 x 5 | Yes | Yes | Coin-size, single chips, reference specimens | |
| 4.5 x 6 | Yes | Yes | Small chips, panned concentrates | |
| 5 x 8.5 | Yes | Yes | Yes | Soil and small chip samples, about 0.5 kg |
| 5.5 x 10.5 | Yes | Yes | Yes | Soil, stream sediment |
| 7 x 12.5 | Yes | Yes | 1 kg chip samples | |
| 10 x 17 | Yes | Yes | Yes | 2 kg RC sample |
| 12 x 18 | Yes | Yes | Yes | Standard RC and rock chip sample, 2 to 3 kg |
| 12 x 24 | Yes | Yes | Long chip runs, core pieces | |
| 15 x 19 | Yes | Yes | Yes | 3 to 5 kg, split core, met samples |
| 20 x 24 | Yes | Yes | Yes | Bulk chips, whole-core intervals, 5 kg and up |
Other formats: Nano-Por in 11 x 17 (closed or open top), 13 x 26, 15 x 19 and 19 x 22. Micro-Por PE in 11 x 17, 13 x 20, 13 x 26 and 19 x 22. Polyethylene in 9 x 16, 10 x 20, 12 x 18, 12 x 24, 18 x 24, 20 x 30 and 28 x 40, in 4, 6 or 8 mil. Seal-top polyethylene from 2 x 3 to 13 x 15. Kraft tin-tie soil envelopes in 3 x 5, 3.5 x 6, 4 x 7 and 5 x 9. Kraft coin envelopes in 3 x 4.5 and 3-1/8 x 5.5. Canvas wrap-tie in 6 x 11, 10 x 17, 15 x 19 and 17 x 28; canvas draw cord in 7 x 12 and 10 x 18.
How many bags does a program need
For RC or chip sampling: hole depth divided by sample interval, plus QA/QC samples. A 1,000 ft RC hole on 5 ft intervals is 200 samples. Add duplicates, blanks and standards, typically 1 in 20 each, so about 230 bags, and round up to whole boxes: 3 boxes of 100. For soil grids: one envelope or bag per station, plus 5 to 10 percent for duplicates and re-sampling.
| Program | Samples | Bags to order |
|---|---|---|
| 1,000 ft RC hole, 5 ft intervals | 200 | 3 boxes of 100 |
| 10 such holes | 2,000 | 23 boxes of 100 |
| 500-station soil grid | 500 | 550 kraft envelopes (3 boxes of 250) or 6 boxes of 100 bags |
| 300 m diamond hole, 1 m splits | 300 | 4 boxes of 100 Heavy Protexo or Sentry |
Barcodes and labeling
Every Protexo, Heavy Protexo, Nano-Por, Micro-Por and canvas bag has a sewn-in 2 x 3 in waterproof yellow tag, blank on one side for the sample number and printed with a standard sample format on the other. Heavy Sentry bags carry a heat-resistant barcode tag with a unique number on every bag, so the lab can scan straight from the bag after oven drying. Protexo 12 x 18 is also stocked pre-barcoded. Custom-printed tags and barcode ranges are available for drill programs.
Frequently asked questions
What bag should I use for RC chip samples?
A CGS Protexo 12 x 18 in cloth bag. It breathes, so damp cuttings dry, it takes a marker and a tag, and it is the size most exploration crews use for a standard sample.
Which sample bags can go in a drying oven?
Heavy Sentry polyester bags with the heat-resistant barcode tag are rated to 325 F. Micro-Por PE bags are rated to 400 F. Protexo, Heavy Protexo and canvas bags are rated to 250 F.
What is the difference between Protexo and Heavy Protexo?
The cloth. Protexo is a 50/50 poly-cotton blend. Heavy Protexo is a heavier unfinished 100% cotton for heavier, sharper rock and rougher transport. Same sizes, same drawstring, same tag.
What sample bag do I use for soil samples?
Kraft tin-tie envelopes (3 x 5 to 5 x 9 in) for standard geochem soils, or a 5 x 8.5 in Protexo bag when the sample is larger or wet. Seal-top polyethylene if the soil has to stay sealed.
Can I get sample bags with barcodes?
Yes. Heavy Sentry bags come with a unique barcode on every bag as standard, and Protexo 12 x 18 is stocked pre-barcoded. Custom barcode ranges can be printed for a program.
Are cloth sample bags waterproof?
No, and that is the point: cloth breathes so samples dry instead of sweating. For wet samples or anything that must not leak, use polyethylene or seal-top bags. For samples that need to drain, use Nano-Por.
How many sample bags come in a box?
Cloth and polyester bags come 100 to a box. Canvas bags come 25 to a box. Kraft envelopes come 250 to a box and coin envelopes 500. Polyethylene bags come 250 to a box.
How fast do sample bags ship?
In-stock orders placed by 2:30 pm Pacific, Monday to Friday, ship the same day from Sparks, Nevada, or pick up at the counter.
Written by the CGS Mule team, Sparks, Nevada. Updated October 2026.