Recently, there has been a dramatic shift from the traditional putty to glazing silicone in window glazing. As a matter of fact, the two window glazing techniques work well.
However, choosing either glazing silicone or putty depends on your understanding of the two technologies. That is, from their chemistry, long-term performance and durability.
Therefore, before you make a final decision on whether go for putty or silicone window panes, let’s get the facts right.
What Is Glazing Silicone?
Glazing silicone is an artificial elastomer sealant composed of silicone polymers that are specifically intended to be used in joining glass with frames. It is flexible once cured and capable of stretching and compressing as the window assembly moves with temperature variations or structural changes. The contemporary glazing silicones have been designed to be highly adhesive, UV stable and have the ability of sealing water.
What Is Glazing Putty?
Glazing putty is an ancient material that has been in use since time immemorial in the installation of windows. It is generally oil-based and includes linseed oil and chalk or whiting to create a workable paste. Putty slowly hardens when it is applied owing to the oxidation of oils. Putty is not as elastic as silicone; it depends more on compression and mechanical hold.
Material Composition and Chemistry
· Silicone Polymer Structure
Glazing silicone is created using cross-linked chains of silicone polymer which forms a flexible molecular net. This design will enable the treated sealant to stretch a long way without rupturing. Silicone polymers are not reacted to ultraviolet radiation, moisture, and extreme temperatures, so they are chemically stable in outdoors use.
· Oil-based and Linseed Putty Composition
Conventional glazing putty uses natural fillers and oils. Oxygen in the air reacts with linseed oil, and it polymerizes slowly, which makes your putty to harden with time. The mineral fillers give it body and shape so that the material can be molded into a smooth bevel.
Nevertheless, since the curing is oxidation-driven, the environmental conditions have a significant impact on drying duration. Putty may take days or weeks to fully harden.
Its chemical structure is basic and old-fashioned, and it does not have the same resistance and strength to elasticity of contemporary synthetic sealants.
Application Methods on Window Glazing Surfaces
One of the key fundamental aspects whenever you are choosing any glazing material is surface preparation technique and application method.
· Surface Preparation
Both silicone and putty must be placed on clean, dry surfaces, although silicone requires more rigorous preparation. Silicone installations may also require primers to enhance bonding, particularly on metal or coated surfaces. Putty is less critical and adheres well to porous wooden frames and that is why it has been traditionally popular in timber windows.
· Curing and Setting Behavior
Silicone is cured by exposure to moisture and develops a skin in a short time, in most cases within minutes. Depending on thickness, full curing can require up to 24 hours. Putty, on the contrary, is healed gradually by oxidation.
· Tooling and Finishing
Silicone needs to be carefully tooled in order to get a clean bead and then it skins over. After it has been treated, it cannot be remodeled. The putty is more durable and can be reshaped, so the installer can refine the surface with a knife. This prolonged working time comes in handy in decorative or restoration work.
Evaluating Glazing Silicone and Putty Performance
Now, this is again another variable you cannot ignore. It is important you evaluate the performance difference of these two popular glazing materials.
· Movement and Flexibility
Silicone has a high movement tolerance. It stretches and compresses and does not crack, and this makes it perfect in the contemporary buildings where expansion and contraction are anticipated. Compared to frame tagging, putty is relatively rigid and can crack when frames change by a significant margin.
· Adhesion Strength
Silicone adhesive has a strong bond with glass, aluminum, and most plastics. It adheres both chemically and mechanically. Putty is more dependent on compression and surface grip, which may deteriorate with time in case of excessive drying of the material.
· Weather and UV Resistance
Silicone is very resistant to sunlight, moisture and extreme temperatures. It continues to perform even in extreme climate. Putty is also more susceptible to UV radiation and can dry up, crack or contract without protective coats of paint.
· Water Sealing Capability
Silicone creates a watertight membrane which lasts years. Putty is an excellent waterproof sealant when maintained but can form micro-cracks over time.
· Durability and Lifespan
Aging Characteristics
Silicone is resistant to aging and can take decades to become elastic. Most architectural silicone manufacturers have 20-30 year service ratings. Putty will undergo the process of oxidation and loss of oil which will cause stiffening and cracking.
Crack and Shrink Resistance
Silicone does not shrink or crack because of its elastic structure. Knowing that oils evaporate, putty may shrink, leaving holes that need to be repaired.
Maintenance Needs
Once installed, silicone does not need many repairs. Putty should be taken care of by being inspected and repainted to avoid damage by the environment.
· Compatibility Considerations
Glass Types
Most of the contemporary glass types, such as insulated and coated, are compatible with silicone. Putty typically safe on regular glass but might not be compatible with some specialty finishes.
Frame Material (Wood, Aluminum, & PVC)
Silicone tack is also compatible with aluminum, PVC and can be used on wood with adequate preparation. Putty works best on wood and not on metal or plastic frames.
Ability to Paint
After drying, putty is easy to paint. The majority of silicones cannot be painted unless they are formulated as paintable sealants.
· Installation Environments
Residential Glazing
In current houses, aluminum and PVC frames are usually used and coated with silicone. In vintage wooden windows, Putty has been used.
Commercial Glazing
Silicone is preferred in commercial systems because of its strength, durability, and its conformity with the current building standards.
Preservation and Conservation
In heritage restoration, putty is used to maintain original look and material.
Whether to Choose Glazing Silicone or Putty
- Climate Conditions: Silicone is superior in extreme weather and excessive use of UV. Putty can also be used in the less severe climates where it can be maintained regularly.
- Structural Movement: Silicone can be easily moulded into buildings with observable dilatation.
- Aesthetic Requirements: Putty is commonly preferred as a visual aid in historic aesthetics.
- Maintenance expectations: Silicone is the preferred material if low maintenance is a priority.
Comparison Table
| Feature | Glazing Silicone | Glazing Putty |
| Flexibility | Highly elastic | Rigid after curing |
| Lifespan | 20–30 years typical | Requires periodic replacement |
| UV resistance | Excellent | Moderate with paint protection |
| Paintable | Usually no | Yes |
| Movement tolerance | High | Low |
| Maintenance | Minimal | Regular upkeep required |
| Best use | Modern glazing systems | Heritage wooden windows |
FAQs
Which lasts longer in outdoor glazing?
Silicone glazing generally has a much longer lifetime outdoors as it is immune to UV radiation, thermal extremes and moisture without becoming brittle. It is elastic in structure and can absorb movement without cracking.
Can glazing silicone be painted?
The majority of standard glazing silicones are not paintable as paint adheses poorly to silicone that is cured. There are special paintable hybrid sealants that are available, though pure silicone typically resists coatings.
Is putty better for wooden window frames?
Putty has continued to be a good option in wooden frames, particularly in conventional sash windows. It has a natural bond with wood and it facilitates genuine restoration.
Which is easier for beginners to apply?
Putty is usually simpler to learn since it is workable longer and correctable. Silicone needs cleaner and faster tooling as it skins easily.
Can silicone replace traditional putty in restorations?
Yes, technically, but that might not suit heritage projects. The restoration work is frequently focused on historical accuracy and material authenticity. Silicone has the ability to transform the aesthetics and repair technique of traditional windows.
Trust Legensilico for all Your Silicone Products
At Legensilico, we formulate different silicone products. From glazing silicone, silicone glue to silicone sealants.
Every product is designed to meet the highest quality standard and guarantee reliable performance. With our years of experience in the industry, our team will formulate every products to match your specific project needs – request for our products catalogue now.
