Nano Banana Tutorial: Optimizing Prompts for Accurate Glass Transparency on Coffee Tables
Creating realistic glass objects in AI-generated images often presents a unique challenge. When generating scenes featuring coffee tables with glass tops, users frequently encounter issues where the surface appears opaque, like solid plastic, or suffers from excessive, unnatural reflection that obscures the items beneath. This tutorial focuses specifically on optimizing your prompts within Nano Banana to achieve accurate transparency, proper refraction, and clear background visibility.
It is important to understand that Nano Banana refers to the AI image generation and editing tool discussed here. It is not a skincare brand, bottle, jar, or physical subject. The platform supports text-to-image and image-to-image workflows, allowing you to refine these visual details through precise instruction. By adjusting specific prompt parameters, you can guide the model to render the complex optical properties of glass more effectively.
Understanding the Core Challenge
The primary difficulty in rendering glass lies in balancing two competing visual traits: transparency and reflectivity. In many generated scenes, the model defaults to treating the glass as a solid, opaque material because it prioritizes the texture of the table legs or the objects sitting on top. Alternatively, it may overemphasize reflections, creating a mirror-like effect that hides the interior of the room or the items placed on the table entirely.
To solve this, your prompt must explicitly define the optical behavior of the surface. You need to instruct the model to prioritize light passing through the object rather than bouncing off it. This involves using descriptive language that emphasizes clarity, depth, and the interaction between the glass and the environment behind it. Without these specific cues, the AI may default to generic material definitions that lack the nuance required for high-fidelity glass simulation.
Step-by-Step Prompt Optimization Strategy
To achieve the desired result, follow these structured steps when crafting your input for Nano Banana. These instructions are designed to be copied or adapted directly into the generator's prompt library.
- Define the Material Explicitly: Start by clearly stating the material composition. Use phrases like "clear tempered glass," "transparent glass surface," or "see-through glass tabletop." Avoid vague terms like "shiny" or "smooth" without context, as these can lead to metallic or plastic interpretations.
- Specify Refraction and Visibility: Directly address the issue of opacity. Include instructions such as "background visible through the glass," "objects underneath clearly seen," or "light refracting through the surface." This tells the model that the primary function of the glass is to allow vision through it.
- Control Reflection Intensity: To prevent the overly reflective look, add modifiers that reduce glare. Phrases like "minimal specular highlights," "subtle reflections only," or "matte edges with transparent center" help balance the lighting. Ensure you mention what should be reflected (e.g., "soft reflection of the room") rather than leaving it open-ended.
- Contextualize the Scene: Describe the environment surrounding the table. Mentioning "a cozy living room visible beneath the table" or "books and a lamp seen through the glass" provides the model with reference points for what needs to appear through the transparent layer.
- Iterate with Negative Constraints: If the initial result is still too opaque, consider adding negative constraints if the interface supports them, or rephrase the prompt to emphasize the absence of opacity. For example, "no solid surface, fully see-through" can reinforce the transparency requirement.
Evaluating and Fixing Results
After generating an image, you must evaluate whether the glass behaves correctly. Look for the following indicators:
- Background Clarity: Can you clearly distinguish objects located behind or under the table? If the view is blocked, the glass is likely too opaque.
- Refraction Accuracy: Do objects viewed through the glass appear slightly distorted or shifted, mimicking real-world physics? A lack of distortion might indicate a flat, non-refractive surface.
- Reflection Balance: Are there reflections, but do they not dominate the image? The glass should act as a window, not a mirror.
If the results are unsatisfactory, try refining your prompt by increasing the weight of transparency keywords or simplifying the scene description to reduce confusion. Remember that prompt instructions describe desired outcomes; they do not guarantee identity, label, object, or typography preservation. Therefore, slight variations in the final output are normal.
For those looking to experiment further, you can explore the prompt library for additional examples. Note that while Google documents Nano Banana 2 as Gemini 3.1 Flash Image, Nano Banana Pro as Gemini 3 Pro Image, and Nano Banana 2 Lite as Gemini 3.1 Flash Lite Image, these are distinct models with different capabilities. Specifically, Nano Banana 2 Lite is focused on speed and cost and is not optimized for multiple reference inputs or multi-turn sequential editing. Do not recommend it for complex workflows requiring these features without explaining this limitation.
By carefully constructing your prompts with these specific parameters, you can significantly improve the realism of glass surfaces in your generated coffee table scenes. Always remember that untested prompt examples provided in documentation are just examples, and results may vary based on the specific model version used.