Few things are more frustrating than carefully arranging dried wedding flowers in a mold, pouring crystal-clear epoxy over them, and then discovering bubbles trapped around the petals. The good news is that most bubbles in resin flower preservation can be prevented with the right preparation and pouring technique.
Flowers are naturally full of tiny spaces where air can hide. Petals, flower centers, stems, and overlapping leaves can all trap air. Once epoxy surrounds the flower, that air may slowly escape and form bubbles in your casting.
Why Do Flowers Create Bubbles in Resin?
Even completely dried flowers contain countless small pockets between petals and inside their structure. When resin flows into those spaces, displaced air needs somewhere to go. If the resin is already too thick or the flower is completely submerged, the air can become trapped.
Other common causes include mixing epoxy too aggressively, pouring too quickly, using resin that is too cold, and attempting a deep pour in one layer when the resin is not designed for that depth.
1. Make Sure Your Flowers Are Completely Dry
Never embed fresh flowers directly in epoxy resin. Moisture can cause cloudiness, discoloration, curing problems, and bubbles.
Wedding flowers should be thoroughly dried before casting. Silica gel is one of the most popular methods because it helps flowers retain more of their original shape and color.
If you are still preparing your bouquet, read our guide on how to dry wedding flowers for resin preservation before you begin casting.
2. Warm the Resin Before Mixing
Cold epoxy is thicker, which makes it harder for bubbles to rise to the surface. Bringing unopened resin bottles to a comfortable room temperature before mixing can reduce viscosity and help trapped air escape.
Do not overheat epoxy. Excessive heat can shorten working time and accelerate the curing reaction. Always follow the temperature recommendations for the resin system you are using.
3. Mix Slowly and Thoroughly
Aggressive mixing can whip hundreds of tiny air bubbles into epoxy. Instead, mix slowly while scraping the sides and bottom of the mixing container.
The goal is complete mixing without creating unnecessary turbulence. After mixing, allowing the resin to rest briefly can give some bubbles time to rise before you pour, provided this remains within the product's working time.
4. Seal Porous Flowers When Necessary
Some dried flowers release air much more aggressively than others. Dense flower centers, dried greenery, and highly textured petals can continue releasing bubbles after the main pour.
A thin sealing coat of resin can help. Brush a small amount of mixed epoxy over problem areas and allow it to settle before completing the larger pour. This fills many of the tiny air pockets before the flower is surrounded by resin.
5. Pour Resin Around the Flowers Slowly
Instead of dumping resin directly over the bouquet, pour slowly into the mold and allow the resin level to rise around the flowers.
A slow pour gives displaced air more time to escape. Watch the flower centers and areas where petals overlap. These locations commonly release bubbles several minutes after resin reaches them.
6. Use Multiple Layers for Deep Flower Castings
Large wedding bouquet blocks can require a significant amount of epoxy. The resin must be designed for the depth you intend to pour.
For deep floral preservation projects, a casting resin such as Culture Cast Casting Resin is a better choice than a coating resin designed for thin applications.
Depending on the mold depth and resin specifications, pouring in controlled layers can make it easier to position flowers, release trapped air, and avoid excessive heat during curing.
Not sure how much resin your mold will require? Use our guide on how much epoxy you need for wedding flower preservation.
7. Check for Bubbles More Than Once
Do not assume the casting is bubble-free just because the surface looks clear immediately after pouring. Flowers may continue releasing trapped air for a while.
Inspect the casting several times during the early working period. Look closely around flower centers, underneath petals, beside stems, and along the mold walls.
If a bubble is accessible, you can often guide it toward the surface with a clean mixing stick or similar tool before the resin begins to thicken.
8. Use a Large Torch for Fast Bubble Removal
For surface and near-surface bubbles, Counter Culture DIY prefers a larger torch used quickly rather than lingering over the resin with a heat gun or relying on a very small torch.
The reason is speed. A larger torch can rapidly heat the air trapped inside a bubble so the air expands and escapes through the resin. The goal is to pop the bubble quickly without spending enough time heating the entire mass of epoxy.
That matters because warming the resin itself lowers its viscosity, making it thinner, and too much heat can accelerate the curing reaction. Excessive heating can shorten working time and, in extreme cases, contribute to an uncontrolled or flash cure.
Keep the torch moving and use brief passes. You are trying to affect the bubbles, not heat-soak the resin, flowers, or mold. Always follow the safety and heat-use instructions for the specific resin and mold you are working with.
9. Arrange Flowers So Air Can Escape
Flower placement matters. Tightly compressed petals and flowers pressed firmly against the bottom or side of a mold can create pockets where air has no easy escape route.
When possible, leave small pathways for resin to flow around the flowers. Positioning an open bloom so trapped air has a path upward can also help. Pouring a base layer first can make it easier to position the arrangement before the final casting layers are added.
What If You Already Have Bubbles in Your Resin?
If the epoxy is still within its working time, accessible bubbles can often be released by gently moving them toward the surface and then using a quick torch pass when appropriate.
Once the resin has cured, removing internal bubbles is much more difficult. Small surface imperfections may sometimes be sanded and recoated, but bubbles deep inside a finished flower block generally cannot be removed without significantly altering the piece. Prevention is much easier than repair.
Best Resin for Clear Wedding Flower Castings
For thick molds and bouquet preservation, choose a resin formulated for casting rather than a standard tabletop coating epoxy. A lower-viscosity casting resin has more time to flow around detailed flowers and allows trapped air to rise.
Read our complete guide to choosing the best resin for wedding flower preservation before starting your project.
Quick Bubble-Prevention Checklist
- Dry flowers completely before casting.
- Use resin at the recommended room temperature.
- Mix slowly instead of whipping the epoxy.
- Seal flowers that release excessive air.
- Pour slowly around the arrangement.
- Use a casting resin appropriate for the pour depth.
- Inspect flower centers and overlapping petals for trapped air.
- Recheck the casting during the resin's working time.
- For accessible bubbles, use brief passes with a larger torch rather than heating the resin for an extended period.
Preserve Your Flowers With Fewer Bubbles
A clear flower casting starts long before the epoxy cures. Properly dried flowers, careful mixing, slow pouring, smart flower positioning, and the right casting resin dramatically reduce the chance of trapped bubbles.
If you are preserving a wedding bouquet for the first time, start with our complete step-by-step wedding flower preservation guide. You can also learn how to keep flowers from turning brown in resin and explore wedding bouquet preservation ideas for your finished keepsake.