Why Your Builder Gel Is Growing Little Mounds
PNTA Education
Why Your Builder Gel Is Growing Little Mounds
(And How to Fix It)
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You've cured your building layer, gone to file, and noticed something odd — tiny raised mounds dotting the surface of your work. It can look like the gel has bubbled up, or even blistered. If this has happened to you, you're not alone, and the good news is it's completely preventable once you understand what's actually going on.
What's Causing Those Mounds?
This is a curing phenomenon, and it comes down to bubbles trapped in your building layer.
When you cure a builder gel, the outermost surface hardens first. If there are bubbles sitting lower in the product — ones you may not have noticed during application — the uncured gel beneath them is still in motion. As the molecules begin to cross-link and the gel contracts slightly during cure, that softer, still-fluid gel gets pushed upward through the bubble and cures in a little mound on the surface.
In short: The outer layer sets, traps the movement underneath, and the uncured gel finds the path of least resistance — up and out through the bubble.
This is most common with builder-in-a-bottle gels — products like Lastik, Lastik Plus, and our upcoming release PUGLE — where the brush lives inside the product. Every time you dip and withdraw your brush, there's opportunity to introduce air into the bottle.
How Bubbles Get Into Your Bottle
Here's the thing: most techs don't realise they're doing it. The way you remove your brush from the bottle is the main culprit.
If you pull your brush straight up through the neck of the bottle, you create a vacuum effect. When the brush clears the product, air rushes in to fill the space — and bubbles get pushed down into your gel. Over time, those bubbles accumulate and settle throughout the formula. You might not see them sitting on top of the product — but they're there, waiting to appear during cure.
The Brush Technique That Prevents Bubbles
This is something we teach all of our students at PNTA, and it makes a significant difference.
Step by Step
- As soon as you open your bottle, clear the thread on the neck of the bottle as usual.
- Before withdrawing the brush fully, find the flat side of the brush stem.
- Rest that flat side against one side of the bottle neck as you pull the brush out.
- This maintains a gap between the product and the bottle wall, so air isn't forced down into the gel.
- When reinserting your brush, check that there is a clear opening at the base of the neck. If a bubble has formed across the opening, gently pop it before inserting your brush.
Tip: If you work with junior techs or new staff, make this part of how you train them from the start. Good bottle habits early = fewer troubleshooting headaches later.
What To Do If Your Bottle Already Has Bubbles
If you've picked up your bottle and noticed the product looks bubbly, don't stress — there's a simple fix.
The Overnight Cap Trick
- Rest your cap in the bottle without twisting it down onto the threads.
- Make sure the clear neck of the bottle is still covered by the resting cap — you don't want any light sneaking in and pre-curing your product.
- Leave it overnight. Without the pressure of a sealed cap, bubbles are free to rise to the surface and pop on their own.
Why does pressure matter? When you screw the cap down tightly, you're essentially sealing the bubbles in place. Removing that pressure gives them room to move.
Quick Recap
| Problem | Cause | Solution |
|---|---|---|
| Mounds after curing | Bubbles trapped in building layer | Prevent bubbles entering the bottle |
| Bubbles in bottle | Brush withdrawal technique | Use flat-stem technique when removing brush |
| Existing bubbles in product | Sealed cap trapping them | Overnight rest with cap loosely placed |
The Bottom Line
Builder-in-a-bottle gels are a fantastic tool — they're versatile, efficient, and when used correctly, give beautiful results. But they do require a little more attention to technique than a pot-based product, simply because of how the brush interacts with the formula.
Once you adjust your brush technique and understand how bubbles behave during cure, those mysterious little mounds become a thing of the past.
Have questions about technique or product application? Reach out to the PNTA team.
