Recently, sampling inspection results of commercially available squishy toys by multiple testing institutions have drawn widespread attention. According to CCTV reports, all 11 squishy samples submitted for testing were found to contain total volatile organic compounds, with a formaldehyde detection rate of 73%, and some samples exceeding the formaldehyde standard by up to 185 times. An independent investigation by the Shenzhen Zero Waste Environmental Public Welfare Development Center (Toxic-free Pioneer) similarly showed a 100% exceedance rate among the 11 samples tested.

As practitioners in the liquid adhesive industry, it is necessary for us to clarify from a materials science perspective: where does formaldehyde actually come from? What kind of material solution can truly return squishy toys to their essence of "safe stress relief"?

Sources of Formaldehyde: More Than Just a "Glue" Problem

Squishy toys are not single-material products. The core materials of commercial products cover multiple systems including polyurethane (PU), polyvinyl chloride (PVC), thermoplastic rubber (TPR), and silicone. Different material systems release harmful substances for different reasons.

In PU foam systems, during synthesis and foaming, the reaction between isocyanates and polyols may leave unreacted monomers and small-molecule volatile organic compounds, with formaldehyde being a common one. PVC systems are inherently rigid plastics that must be compounded with plasticizers to achieve a soft feel, making phthalate plasticizers standard—and some inexpensive plasticizers may be accompanied by the release of aldehyde volatiles during production or use. Even products claiming to be "silicone" may similarly introduce volatile harmful substances if low-quality color pastes, curing agents, or non-standard vulcanization processes are used.

Even more concerning is the "secondary contamination" from packaging bags. The Toxic-free Pioneer investigation found a key detail: the plasticizer content of all 11 squishy toy bodies was compliant, but the phthalate exceedance rate in the accompanying sealed bags reached as high as 301 times. PVC sealed bags add large amounts of plasticizers in pursuit of a soft feel, and when consumers knead through the bag, their hands directly contact precisely the part where risk is most concentrated. Some products even label "recommended to knead through the bag for better feel," invisibly directing consumers toward a higher-risk usage method.

Which Material Is Safest? The Logic and Prerequisites of the Silicone System

Among common materials, platinum-cured liquid silicone rubber (LSR) has a structural advantage in safety, but this advantage comes with strict prerequisites.

From a chemical mechanism perspective, addition-cure liquid silicone rubber crosslinks through hydrosilylation, a reaction that produces no small-molecule byproducts and theoretically requires no plasticizers to achieve a soft feel. Silicone rubber itself has far superior thermal stability to PVC and PU, and will not decompose to release formaldehyde or benzene series compounds at normal use temperatures. Comparative testing data from Taiyuan University of Technology provides an intuitive reference: under identical test conditions, the xylene release of unlabeled squishy toys reached 42.65 mg/m³, TPR material was 23.71 mg/m³, while silicone material was only 2.56 mg/m³. The gap between material systems is orders of magnitude.

But the word "silicone" does not automatically equal safety. A large number of squishy toys on the market labeled "food-grade silicone" are actually unlabeled products, possibly using industrial-grade silicone, recycled silicone, or low-quality compounded rubber with inexpensive volatile solvents added. Although the base material of such products is silicone rubber, impurities in color pastes, crosslinking agents, or diluents are sufficient to push VOC emissions to dangerous levels. The safety of silicone depends on full-chain quality control from base gum to color paste, from catalyst to packaging bag—not on a material name.

Material Selection Logic for Liquid Adhesive Enterprises: How to Avoid Pitfalls

For downstream product manufacturers, the safety risk of squishy toys is essentially a matter of raw material admission and supply chain control. The following three principles can serve as reference.

First, request complete compliance documentation, not just a "test report." A compliant liquid silicone rubber supplier should be able to provide VOC emission data for the base gum, heavy metal content testing, and compositional safety statements for color pastes and additives. If a supplier can only provide a general report stating "complies with GB 6675" without being able to break down specific indicators, their quality control capability warrants careful evaluation. The new national standard GB 6675.1-2025, effective November 1, 2026, for the first time incorporates formaldehyde, benzene series, and TVOC emissions into mandatory toy control, and sets special limits for sealed-packaging products such as squishy toys. Screening materials in advance according to the new national standard is the optimal path to avoiding subsequent compliance risks.

Second, be wary of formulation distortion caused by "feel-first" priorities. Squishy toys pursue special tactile sensations of slow or fast rebound, and some manufacturers add excessive silicone oil or softeners to silicone for this purpose. When silicone oil addition exceeds the compatibility limit of the base gum, it not only damages mechanical properties but may also migrate and exude during use, becoming a potential source of VOCs. Hardness adjustment of liquid silicone rubber should be achieved by adjusting crosslink density and the vinyl/hydrogen ratio, rather than relying on externally added aids.

Third, packaging bags must be included in the material evaluation scope. This is currently the most easily overlooked aspect of squishy toy safety control. If the product comes with a sealed bag, suppliers should be required to provide phthalate testing data for the bag material. If safety cannot be confirmed, it is recommended to switch to PE or PP packaging without plasticizers, or simply eliminate the sealed bag design. A PVC bag worth a few cents is enough to reduce the entire product's safety investment to zero.

The safety issue of squishy toys is essentially a trade-off between material selection and cost control. The liquid silicone rubber system provides the chemical foundation for safety, but this foundation can only be translated into real protection for end products under strict raw material admission and process control. For liquid adhesive enterprises, this is both a technical threshold and a market opportunity—when consumers begin to screen products by "does it have an odor" and "do I dare to knead it directly with my hands," truly reliable silicone material solutions will receive the market returns they deserve.

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