Nano Banana 2 Prompt Strategy for Hands Interacting with Transparent Glass

Generating images where human hands interact with transparent surfaces like glass presents a unique challenge for AI image models. The difficulty often lies in the model's tendency to either ignore the transparency, causing hands to appear floating, or to create visual artifacts where the fingers merge incorrectly with the background. When using Nano Banana 2, which is identified by Google as Gemini 3.1 Flash Image, success relies less on defining the object as "glass" and more on describing how light behaves at the interface of skin and transparent media.

The core strategy involves shifting the prompt focus from explicit material definitions to lighting cues. Instead of simply stating "a hand holding a glass," effective prompts describe refraction, highlights, and the subtle distortion of objects seen through the medium. This approach guides the model to understand the physical properties of the scene rather than just the semantic labels. By prioritizing these visual interactions, users can achieve cleaner compositing where the hand appears naturally integrated into the environment, whether it is reaching through a window or gripping a bottle.

Leveraging Lighting Cues Over Material Labels

A common mistake when prompting for complex interactions is over-specifying the material properties. While one might be tempted to write "transparent glass," this often leads to generic plastic-like textures that lack depth. A more robust method is to describe the optical effects caused by the glass. For instance, mentioning how light bends around the fingers or how the background blurs slightly behind the hand provides the necessary context for the model to calculate the correct geometry.

When constructing your prompt, consider adding descriptors related to specular highlights and refraction. Phrases like "light refracting through the fingertips" or "subtle distortion of the background visible through the palm" signal to the engine that there is an intervening layer. This technique is particularly useful in Nano Banana 2 because it allows the model to infer the transparency based on the lighting physics described, rather than relying on a rigid definition that might not translate well across different styles. It is important to note that while prompt instructions describe desired outcomes, they do not guarantee identity, label, object, or typography preservation. Therefore, these descriptions should be treated as guiding principles for the visual generation process.

Five Distinct Prompt Strategies for Glass Interactions

To help you navigate various scenarios involving hands and transparent surfaces, here are five materially different usable prompts. These examples illustrate how adjusting the focus of the description changes the output. Please remember that these are examples of prompt structures; actual results may vary based on the specific generation run.

Example 1: The Refractive Grip

Prompt: "Close-up of a hand gripping a clear drinking glass, light bending around the knuckles, slight distortion of the table surface visible through the glass wall, soft shadows cast by the fingers, photorealistic lighting." When it helps: Use this when the hand is actively holding an object made of glass. The focus on light bending around the knuckles ensures the fingers wrap correctly around the curve without merging into the solid form. Adjustment: If the glass looks too opaque, add "highly transparent" or "crystal clear" to emphasize the lack of color tint.

Example 2: The Background Through-Finger

Prompt: "A hand pressed against a large window pane, city skyline visible but blurred through the palm and fingers, rain droplets on the glass surface, cool blue ambient lighting, cinematic composition." When it helps: Ideal for scenes where the hand is behind or touching a barrier, separating the subject from the background. The instruction to make the background visible through the fingers forces the model to render the transparency layer correctly. Adjustment: To increase realism, specify the texture of the glass, such as "frosted edges" or "clean polished surface," depending on the desired mood.

Example 3: The Subsurface Scattering Effect

Prompt: "Hand resting on a thick glass block, warm sunlight passing through the fingertips creating a reddish glow on the skin, sharp reflections on the top surface, macro photography style." When it helps: This works best for close-ups where the thickness of the glass matters. Describing the light passing through the skin (subsurface scattering) combined with the glass surface creates a convincing sense of volume and material separation. Adjustment: If the skin tone looks unnatural, adjust the color temperature of the light source in the prompt, e.g., "golden hour sunlight."

Example 4: The Reflection and Occlusion Balance

**Prompt": "Person looking through a glass door, their reflection visible on the surface overlapping their face, hand touching the glass from the inside, high contrast lighting, urban night setting." When it helps: Useful for complex scenes involving both reflection and transmission. This prompt explicitly asks for the reflection to overlap the face, teaching the model to handle multiple layers of interaction simultaneously. Adjustment: If the reflection is too strong, reduce the intensity by adding "faint reflection" or "dim lighting."

Example 5: The Abstract Light Play

Prompt: "Abstract shot of fingers interacting with a prism of glass, rainbow light patterns projected onto the hand, sharp focus on the edge of the glass, studio lighting setup." When it helps: Best for artistic or stylized images where the goal is to showcase the interplay of light rather than a literal depiction of a hand holding an object. It focuses on the visual result of the interaction. Adjustment: For a more natural look, replace "rainbow light patterns" with "soft white highlights."

Model Selection and Workflow Considerations

While Nano Banana 2 offers powerful capabilities for these complex interactions, it is crucial to select the right tool for the job. Google documents Nano Banana 2 Lite as focused on speed and cost. However, it is not optimized for multiple reference inputs or multi-turn sequential editing. If your workflow requires refining the hand-glass interaction through several iterations or using multiple reference images to guide the pose, Nano Banana 2 Lite may not provide the stability needed. In such cases, utilizing the standard Nano Banana 2 model is recommended to ensure higher fidelity in handling the nuanced physics of light and matter.

For users seeking advanced features or specific professional workflows, the Nano Banana Pro page details additional capabilities. Always verify the specific model version available in your current session, as features can vary between the Lite, standard, and Pro versions. Remember that the prompt library offers example prompts that users can copy or take into the generator, serving as a starting point for your own creative experiments.

By focusing on the physics of light and the behavior of materials rather than just naming the objects, you can significantly improve the quality of generated images. Whether you are creating marketing assets, artistic illustrations, or product visualizations, understanding these prompt strategies will help you avoid common artifacts. Try Nano Banana to experiment with these techniques firsthand and see how lighting cues transform your image generation results.

For further technical details on the underlying technology, refer to the official Google Gemini image generation documentation. This resource provides comprehensive information on the model families and their specific strengths in handling complex visual data.