Guard Industry

Stain Resistant Sealer Review – ProtectGuard® MG Scores 100%


sealer reviewOn a recent project one of our customers decided to put a number of stain resistant sealers to the test. The goal was to see which stain resistant sealer would be best to use on marble bench tops and splash backs for their clients project. Guard Industry products ProtectGuard® and ProtectGuard® Marble and Granite were independently tested against 4 leading brand penetrating sealers. These products were Actichem AP176, Du Pont Bulletproof, Dry Treat Stainproof and Lithofin Stain Stop Plus.

A fair sealer review requires an independent evaluation. As such all test work was carried out byStone Initiatives A NATA (National Association of Testing Authorities, Australia) accredited testing facility. They are also members of the ASAA (Australian Stone Advisory Association) and ASTM (American Society for Testing Material – Worldwide Standards).

The staining test results in this sealer review are derived directly from Stone Initiatives results. Information regarding application methods, lifespan and VOC’s data has been derived from manufacturers published information. These include Technical Data Sheets (TDS), Application Guides and/or Safety Data Sheets (SDS). Average retail pricing, as published on Australian online retail stores has been used for all cost calculations and comparisons.


Samples of stone were treated with the required coats of each stain resistant sealer in accordance with the manufacturers application guidelines. The sealers were allowed to cure for a minimum of seventy two hours. Following the curing period the surface of the samples were subjected to 20 scrubbing cycles with a red nylon floor pad. This simulates in service cleaning processes. It also removes any excess sealer which did not fully penetrate the surface. The samples were allowed to air-dry before application of the following staining agents to the surface finish:

  • Red Wine (acidic)
  • Olive Oil (stain leaving a film)
  • Black Coffee (stain leaving a trace & slightly acidic)
  • Coca Cola (stain leaving a trace & slightly acidic)
  • Soy Sauce (stain leaving a trace & slightly acidic)

Staining agents were allowed to dwell on the surface for periods of one hour and twenty four hours before attempts were made to remove the stains.

Cleaning was attempted firstly by rinsing the surface with running hot water for a period of 5 minutes followed by wiping with a damp cloth. Any stains still visible were then cleaned vigorously with a red nylon pad and neutral detergent. Then rinsed under hot water. The surface was air dried and then re-evaluated for staining or damage to the surface.

The reason for testing both 1 and 24 hour stain exposures is to determine performance in different situations and applications. In general, most spills will be cleaned up immediately or very shortly after the spill is made. The one hour result best simulates this type of event. Bench top and indoor flooring applications would generally fall into this category. The 24 hour exposure better evaluates what happens when a spill goes unnoticed for a longer period of time. In most instances this would result in the stain drying out on the surface.

Elegant Grey Marble stone samples were used for this test work as per the project requirements. However, marble is notoriously difficult to seal. As such it provides a rigorous performance test of the stain resistant sealers in question. It provides an excellent benchmark. If a penetrating sealer works well on marble it generally performs as well, if not better, on other materials.

As such, the results presented in this sealer review are representative rather than definitive. Sealer stain resistance may vary when applied to different types of stone or other sealed materials.  However, for the purposes of comparing the relative performance of different stain resistant sealers, the results are fair and representative.


The following graphs display the results as determined by Stone Initiatives.

Scores are of 1 – 5 are determined according to the below scale:

– Stain removed after cleaning procedure (scrub with red nylon pad, detergent and hot water).
– Stain very slightly visible (not noticeable upon casual viewing).
– Stain slightly visible (noticeable at close range at casual viewing).
– Stain moderately visible (conspicuous).
– Stain highly visible / permanent damage to surface finish (e.g. etching).

Stone Initiatives state a Stain Index Uncertainty of ± 0.5.

Sealer Stain Resistance Results

The following 4 graphs illustrate the ease of cleaning of stone after being exposed to the 5 stains over both 1 hour and 24 hours. Graphs show individual testing results per stain for both 1 and 24 hours. And an average score rating for both 1 and 24 hours stain exposure time.

Sealer Stain Resistance After 1 Hour Exposure

Stain resistant sealer 1 hour stain resistance scores

Stain Resistant Sealer 1 hour stain test results

Sealer Stain Resistance After 24 hours Exposure

Stain resistant sealer 24 hour stain test results

sealer stain resistance 24 hour average results

Other Results

In addition to staining, Stone Initiatives analysed the surfaces of the cleaned samples to evaluate the extent of surface etching. Etching is caused by acid attack and is a permanent defect. To remove etching the stone needs to be cut back and re-polished. After such a process sealer would need to be reapplied. The results of the etching analysis are presented in the table below.

Unsealed Antichem AP176 Du Pont Bulletproof Dry Treat Stainproof Lithofin Stain Stop Plus Protect Guard Protect Guard MG

Visibility of Etching

Slight to moderate

slight to moderate

slight to moderate

slight to moderate

slight to moderate

none visible

none visible

Sealer Stain Resistance Conclusions

  1. ProtectGuard® MG was the only product to return a perfect sealer stain resistance score.
  2. Protect Guard® matched or outperformed competitors products for all stains except soy sauce.
  3. Only ProtectGuard® and ProtectGuard® MG prevented stains from etching the surface of the stone.

 Additional Sealer Comparisons

Stain resistance is a very important consideration when selecting a sealer. However, it is usually not the only selection criteria. Consideration should also be given to cost, service life, and environmental and health impacts. A high performance sealer may not be feasible for an application if it only lasts for a short period of time, is too expensive or is too hazardous to apply. No sealer review would be complete without considering these details.

For this reason we have also prepared a comparison of these relevant factors for each of the stain resistant sealers tested above. Parameters considered include VOC Content (g/L), Material Price per square meter ($/m2), required number of applications and Life-span (years).

Supply Cost – $/m2

Based on Recommended Retail Pricing (RRP) in Australian Dollars, average coverage (m2) and the number of applications (coats) required.

stain resistant sealer cost per square meter sealer review

Required Number of Applications

Based on information provided on respective technical data sheets for each product.

Stain resistant sealer required number of coats

Sealer Volatile Organic Components

Based on information extracted from individual products technical data sheets or Safety Data Sheets.

stain resistant sealer voc comparison

Du Pont Bulletproof and ProtectGuard® are both water based products.  Therefore, they have much lower VOC’s than the other products which are all solvent based. Their VOC’s are 20 g/L and 2 g/L respectively.

Dry Treat do not publish a specific value for the VOC content of Stainproof. The value shown in the chart is taken from their US shipping category for the product which states it contains a maximum of 650 g/L total VOCs.

The g/L measure for VOC’s can be misleading. Most Volatile Organic Compounds have a low density at room temperature. Many would assume a density similar to water and therefore imagine a maximum VOC value of about 1000 g/L. But maximum obtainable VOC content is much lower. It also varies from product to product depending on the density of the particular VOC present.

For example, ethanol is a volatile organic compound. Pure ethanol contains 100% ethanol and therefore contains 100% VOC’s. The density of ethanol (at 20oC) is 789 g/L and therefore it’s VOC content is also 789 g/L. To put the tested VOC values into context, an ethanol and water mixture with a VOC content of 650 g/L contains about 82% ethanol by mass.

Service Life

As stated by manufacturers in their respective products technical data sheets.

Stain resistant sealer service life comparison

The service life of the products assumes that surfaces are cared for in accordance with the sealer manufacturers care and maintenance guidelines. As a minimum this requires that the surface is not cut back, polished or cleaned with harsh chemicals or abrasives. This sounds fair and reasonable.

However, Stone Initiatives determined that AP176, Bulletproof, Stainproof and Stain Stop Plus all failed to prevent etching. As such, in most applications, spills resulting in etching of some kind will occur several times within the stated service lives of these products. If the etching is polished out the stone needs to be resealed and the service life is reset. So, the practical service life of the sealers is dictated by how often polishing is required to remove etching.

For the purposes this sealer review the benefit of the doubt is given and the full manufacturer quoted service lives are used.

Guard Industry provides a 10 year, AXA Insurance backed, World Wide performance guarantee for both ProtectGuard and ProtectGuard MG. This same warranty applies to most products in the ProtectGuard Range.

Costs Corrected for Service Life

Stain resistant sealer cost per m2 per year

As per the notes in the previous section, instances of etching would would require polishing and reapplication of sealer. This would significantly increase overall lifetime costs. Such scenarios would only see a more dramatic benefit of Guard Industry products relative to their competitors.


  1. ProtectGuard® Marble and Granite is the only product to receive a perfect sealer stain resistance performance score of 5/5.
  2. ProtectGuard® provides a superior stain protection in relation to all other competitors products tested. It outscored every product in every test except the soy sauce tests.
  3. Only ProtectGuard® and ProtectGuard® MG prevented etching.
  4. Both Protect Guard® and ProtectGuard® MG are more cost effective than other stain resistant sealers in terms of material cost.
  5. Due to their single coat application, both ProtectGuard® and ProtectGuard® MG, require less labour to install than the other stain resistant sealers in this sealer review.
  6. ProtectGuard® has an extremely low volatile organic components (VOC) content. Less than all other stain resistant sealers tested.
  7. ProtectGuard® MG has considerably less VOC’s than its comparable solvent based competitors products.

The Guard Industry ProtectGuard® Sealer range outperforms the competition in every category:

  • Better – Superior performance in regards to stain resistance and protection against etching.
  • Cheaper – Lower material cost. Lower labour cost. Lower total life-cycle costs.
  • Safer – Lower VOC’s.
  • Easier – Easy, one coat application.

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