Ideal Thickeners for Paint Stripper Formulations

One common type of renovation is repainting, and the removal of old layers of paint or coatings is a major step in refurbishment or renovation to improve the visual appeal and maximize the protection of the underlying surface. Paint strippers and removers play a critical role in ensuring the repainting process goes smoothly.

Paint Stripper and Paint Remover Formulations

Paint and coating stripper formulations rely on a solvent or blend of solvents to dissolve old paint, varnish, and coating layers, making them easy to remove by scraping or peeling. Viscosity is a key characteristic that distinguishes quality in paint stripper performance. Paint strippers optimized for viscosity will provide good spreadability, making the product easier to apply and minimizing waste by applying incremental amounts and more accurately determining the appropriate volume needed. In many cases, adding the right thickener to a stripper or remover formulation will create a significantly higher-quality product.
 

METHOCEL™ and ETHOCEL™ Thickeners

METHOCEL™ and ETHOCEL™ are naturally derived thickeners based on cellulose from renewable wood pulp. METHOCEL™ is a hydroxypropyl methylcellulose polymer, and ETHOCEL™ is an ethylcellulose polymer. Starting with alkali cellulose, METHOCEL™ is made by treatment to substitute hydroxyl propyl and methyl groups onto the cellulose backbone, while ETHOCEL™ is made by treatment to substitute ethyl groups onto the cellulose backbone. In general, METHOCEL™ is recommended for solutions containing a blend of organic solvents and water, whereas ETHOCEL™ is recommended for solutions only containing organic solvents.

These thickeners have been relied on for several decades to provide rheology modification and thickening in a variety of applications, including paints and coatings, adhesives, ceramics, and more. In the context of paint remover applications, there are specific attributes that make them ideal for optimizing performance:

 

• Shear-thinning rheology modification
• Excellent solubility in aqueous- and various organic-solvent-based solutions
• Chemical inertness and safety

Shear-Thinning Rheology Modification

When METHOCEL™ and ETHOCEL™ are added to aqueous- or solvent-based solutions, they increase viscosity and impart shear-thinning rheology. As previously mentioned, viscosity is an important performance attribute for paint strippers to minimize waste and make the product easier to apply.

When paint strippers are applied to vertical or overhead surfaces, such as with houses, formulations with insufficient viscosity will cause sagging and dripping, leading to waste and ineffective coverage. In this case, METHOCEL™ and ETHOCEL™ serve two purposes: they make brush or spray application easier only while the formula is under high shear, and they rebuild viscosity and keep the formula in place when it is left on the surface and shear is removed.

Excellent Solubility in Various Solvents

Depending on which solvent is being used in each paint, varnish, or coating stripper formulation, selecting the right product is critical to achieving a solution that is clear, smooth, and easy to spread. METHOCEL™ and ETHOCEL™ are recommended for paint stripper applications because one or the other will provide excellent solubility in a wide range of solvents and solvent blends. As mentioned, METHOCEL™ performs better in organic solvent–water blends, and ETHOCEL™ performs better in organic solvents.

Below is a chart detailing the compatibility and appearance of METHOCEL™ 311 and ETHOCEL™ Standard 300 in various solvents and solvent blends. METHOCEL™ and ETHOCEL™ also reduce the evaporation rate when added to these solvents, leading to higher contact times with the surface and extended efficacy.
 

Solvent	METHOCEL™ 311	ETHOCEL™ Standard 300
Ethanol	Hazy, gels	Clear, smooth
Methanol	Hazy, gels	Clear, smooth
Ethanol/water (40/60)	Clear, smooth	Insoluble
Methanol/water (40/60)	Clear, smooth	Insoluble
THF	Swellable	Clear, smooth
THF/water (60/40)	Clear, smooth	Insoluble
Isopropanol	Insoluble	Clear, smooth
Isopropanol/water (80/20–40/60)	Clear, smooth	Clear, smooth to insoluble
Propylene glycol	Insoluble	Insoluble
Dimethyl formamide	Clear, smooth	Clear, smooth
DOWANOL™ PM	Hazy, gels	Clear, smooth
Benzyl alcohol	Hazy, gels	Clear, smooth
Diethylene glycol butyl ether	Insoluble	Clear, smooth
Dimethyl carbonate	Insoluble	Clear, smooth
Dimethyl sulfoxide (DMSO)	Insoluble	Clear, smooth
CELLOSOLVE™	Swellable	Clear, smooth

Chemical Inertness and Safety

As consumer safety becomes a greater focus for paint stripper and paint remover formulations, limiting hazardous ingredients is important. METHOCEL™ and ETHOCEL™ are naturally derived products that are safe to use and pose minimal risk to the formulator. Contact us for additional product details or safety data sheets.

Recommended Grades and Example Formulations

Below are recommendations and example formulations utilizing METHOCEL™ and ETHOCEL™ grades in paint and coating stripper formulations.
 

Recommended grade	Usage level (%)	Notes
METHOCEL™ 311	0.5–1.5	METHOCEL™ 311 is designed for higher solubility in organic solvents while maintaining full solubility in water.
METHOCEL™ E10M	1.0–2.5	METHOCEL™ E10M requires some water in the formulation to perform well.
ETHOCEL™ Standard 300	1.5–2.5	ETHOCEL™ Standard 300 is designed for organic solvents not blended with water.

Component	Amount (%)
Solvent/solvent blend	95.0–97.0
Surfactant	0.3–2.0
METHOCEL™ 311	1.0–3.0

 

Component	Amount (%)
Dimethyl carbonate (DMC)	58.8
Dimethyl sulfoxide (DMSO)	19.6
Xylene	19.6
ETHOCEL™ Standard 300	2.0

 

Component	Amount (%)
Benzene methanol (benzyl alcohol)	78.4
Diethylene glycol monobutyl ether	19.6
ETHOCEL™ Standard 300	2.0

 

Summary

METHOCEL™ and ETHOCEL™ are ideal thickeners and rheology modifiers for paint stripper formulations because they provide shear-thinning rheology modification and are safe, naturally derived, and soluble in a wide variety of organic solvents and organic solvent–water blends. This leads to paint stripper formulations that last longer, adhere to various surfaces more efficiently, and are safer and easier to formulate. Click below to discuss your paint stripper or remover application and request a sample today.