What the frame will and will not say
The frame uses the ingredient’s practical and laboratory temperatures from the Minnesota table. For rock salt it also looks for an exact row in the six-row dry-salt comparison. An air or forecast temperature is reported as air. It is not converted into a pavement temperature.
A number printed on a bag is compared as a number. A match with 15°F or −6°F does not prove the maker’s test method or performance. An unnamed blend does not inherit a pure ingredient’s limit, and Minnesota’s separate “about 0°F” blend example is not a pass or fail. Sand and grit are traction only. The frame does not estimate bags for a driveway.
Worked example
Rock salt, a pavement reading of 20°F, and a bag that prints −6°F. Twenty degrees is above Minnesota’s 15°F practical reference, and it is an exact table row: 8.6 lb of ice per 1 lb of dry salt, with 20 minutes listed. That time is a published comparison, not a prediction for a walkway. The −6°F on the bag matches the laboratory figure only.
Worked example · rock salt · pavement 20°F
Above the practical reference
At 20°F, the pavement is at or above Minnesota’s 15°F practical reference for rock salt. This supports considering the ingredient; it does not predict clearing time or certify a specific product or surface.
The temperature on your bag. Your bag prints −6°F. It numerically matches Minnesota’s −6°F laboratory reference. A numerical match does not establish the maker’s definition, test method or performance. Read the product instructions or ask the manufacturer.
Your next steps
- Clear as much snow and ice as you can first; deicer is for loosening the remainder so it can be removed.
- Minnesota gives 1–4 lb of rock salt per 1,000 sq ft; its spot-treatment example of 1 lb per 250 sq ft is the upper end of that range. Follow your product instructions and conditions, then remove slush and sweep up excess.
- Check the surface and product instructions before use. NRMCA advises avoiding chemical deicers in concrete’s first winter and warns against magnesium-based salts on concrete.
Source notes and limits
- Minnesota’s comparison table: at 20°F: 8.6 lb of ice per 1 lb dry salt; 20 min listed melt time. These are reference results, not a clearing-time prediction for your walkway.
- Iowa State Extension agrees: sodium chloride is most effective above 15°F.
References and method · Not a surface-safety assessment.
Every published dry-salt row
These six rows are the whole comparison. At 10°F and 5°F the source lists a quantity and says dry salt is ineffective and may blow away. Temperatures between the rows are not filled in.
Copy the frame
Use this snippet on the other site. The framed page links back to Practical Melt. Keep that link; it is part of the embed.
Limits that stay in force
- Below a pavement reading of 15°F, rock salt is below the practical reference. At −6°F it is at the ideal laboratory limit, which is not a working target. Colder than that, the reference does not support melting.
- Iowa State says magnesium chloride melts ice down to −13°F and CMA is effective to approximately −15°F. Minnesota’s practical figures are −10°F and 20°F. The checker shows that disagreement and does not average it.
- For rock salt at or above the practical reference, the result repeats Minnesota’s 1–4 lb per 1,000 sq ft guidance. The 1 lb per 250 sq ft spot-treatment example is the upper end of that range, not a default dose and not a bag count.
Same sources as the line under the title. Checked November 13, 2026.