Question 1

Can A Cracked Or Delaminated Potted Assembly Be Repaired in The Field?

Accepted Answer

Field repair of cracked or delaminated potted electronic assemblies is generally not reliable. Here is why — and what the decision criteria are when evaluating repair versus replacement.

Question 2

Can I Use A Softer Epoxy To Prevent Cracking Without Sacrificing Electrical Protection?

Accepted Answer

Shore A 65 encapsulants provide electrical insulation comparable to Shore D formulas while accommodating thermal expansion mismatch. Here is what changes — and what does not — when switching from Shore D to Shore A potting.

Question 3

How Much Moisture Does Cured Epoxy Potting Actually Absorb in Service?

Accepted Answer

Cured epoxy potting compounds absorb 0.06% to 0.43% moisture by weight. For most indoor applications this does not compromise performance. Here is when bulk moisture absorption becomes a design variable.

Question 4

What Is The Difference Between Epoxy Potting Cracking And Delamination?

Accepted Answer

Cracking propagates through the epoxy body. Delamination is loss of adhesion at the epoxy-substrate interface. Both create moisture ingress pathways, but they have different root causes and different corrective actions.

Question 5

Why Does My Potted Component Crack Even Though It Looked Fine After Assembly?

Accepted Answer

Potted components that look fine at assembly can crack later in service due to thermal expansion mismatch between the rigid epoxy and the substrate. Here is the mechanism and what changes it.

Question 6

Which Epoxy Potting Compound Should I Use If I Don't Have Heating Equipment?

Accepted Answer

If your production line has no oven or heat curing equipment, E-120/H-100 is the clear epoxy potting compound designed for this condition. Shore D 82, 13,000 psi flexural strength, 7-day room temperature cure. Here is what to expect from RT-only production.

Question 7

Is There A Specific Epoxy Potting Compound For LED Encapsulation?

Accepted Answer

LED encapsulation requires high transparency, heat resistance above 100°C, and compatibility with diffuser agents. Standard electronic potting compounds are not designed for these requirements. Here is what makes E-600/H-600 different.

Question 8

What Operating Temperature Do I Need From An Epoxy Potting Compound?

Accepted Answer

Clear epoxy potting compounds in this range cover service temperatures from −30°C to 150°C depending on formula. Here is how to match operating temperature requirements to the right product — and when temperature becomes the deciding variable.

Question 9

Can All Epoxy Potting Compounds Cure At Room Temperature?

Accepted Answer

Most clear epoxy potting compounds in this range can cure at room temperature, but one formula requires heat cure and one is specifically designed for RT as its primary pathway. Here is what to check before assuming RT cure is available.

Question 10

What Is The Difference Between Rigid And Flexible Epoxy Potting Compounds?

Accepted Answer

Rigid epoxy potting compounds (Shore D 80–90) protect against moisture and impact. Flexible compounds (Shore A 65) absorb thermal cycling and vibration stress without cracking. Here is how to decide which type your application requires.

Question 11

How Does Shore A 65 Flexible Epoxy Compare To Shore D Rigid Epoxy For Moisture Protection?

Accepted Answer

Shore A 65 epoxy (E-750/H-750) has higher water absorption than Shore D rigid epoxy — but maintains better moisture protection in thermal cycling environments because it does not crack. Here is the full comparison.

Question 12

Oes Shore A 65 Epoxy Provide The Same Electrical Insulation As Shore D Rigid Epoxy?

Accepted Answer

Shore A 65 epoxy (E-750/H-750) provides dielectric strength of 19 KV/mm — comparable to rigid Shore D formulas. Here is what changes and what stays the same when switching from Shore D to Shore A for electrical potting.

Question 13

Is E-750/H-750 Suitable For Outdoor Electronics Subject To Daily Temperature Swings?

Accepted Answer

E-750/H-750 Shore A 65 has a published use temperature range of −30°C to +80°C and is suitable for outdoor electronic potting subject to daily thermal cycling. Here is what to verify before specifying for outdoor use.

Question 14

When Should I Use Shore A Instead Of Shore D Epoxy Potting Compound?

Accepted Answer

Shore A 65 epoxy is the correct specification when the potted assembly will experience thermal cycling, vibration, or dynamic mechanical stress. Shore D 80 is the default for static indoor applications. Here is how to identify which condition applies.

Question 15

What Is A Refractive Index Of 1.534 And Why Does It Matter For LED Encapsulation?

Accepted Answer

E-600/H-600 has a refractive index of 1.534 as measured. Learn what refractive index means for LED encapsulation and when it is a relevant design specification.

Question 16

What Does 140–150°C Temperature Resistance Mean For LED Encapsulation Applications?

Accepted Answer

E-600/H-600 is rated for 140–150°C continuous service. Learn how this compares to other formulas in the range and what it means for LED operating conditions.

Question 17

Does E-600/H-600 Have A Room Temperature Cure Option?

Accepted Answer

E-600/H-600 does not have a room temperature cure option. Heat cure at 100°C is required. Learn why, and what the cure schedule options are.

Question 18

Why Is E-600/H-600 Recommended For LED Encapsulation Instead Of A Standard Epoxy Potting Compound?

Accepted Answer

E-600/H-600 is specified for LED encapsulation because LEDs require 140–150°C service temperature resistance, refractive index compatibility, and heat resistance that standard RT-capable epoxies do not provide.

Question 19

E-190/H-190 Lists Two Mix Ratios — 100:40 And 2:1. Which Should I Use?

Accepted Answer

E-190/H-190 TDS specifies two valid mix ratios: 100:40 by weight and 2:1 by weight. Both achieve full cure. Learn the difference and how to choose based on your production equipment.

Question 20

What Does The −30°C To +90°C Service Temperature Rating Mean For E-190/H-190?

Accepted Answer

E-190/H-190 has a published use temperature range of −30°C to +90°C and Tg 75°C per TDS. Learn what this means for procurement documentation and how it differs from room-temperature property values.

Question 21

What Does Low Exothermic During Cure Mean For Electronic Component Potting?

Accepted Answer

Low exothermic cure means E-190/H-190 generates less heat during the crosslinking reaction. This matters for large-volume or large-component potting where heat accumulation during cure can stress components or cause dimensional distortion.

Question 22

How Do I Know If My Application Needs E-190/H-190 Instead Of E-700/H-190?

Accepted Answer

E-190/H-190 is specified over E-700/H-190 when potting volume is large enough for cure-time exotherm to be a design concern, or when a documented service temperature range (-30°C to +90°C) is required.

Question 23

Why Does E-132/H-100 Have The Lowest Water Absorption in This Epoxy Potting Range, And When Does It Matter?

Accepted Answer

E-132/H-100 has 0.06% water absorption — the lowest among the six formulas in this range. Here is what drives this difference, and the application conditions where low water absorption translates to meaningful protection benefit.

Question 24

Can E-132/H-100 Be Used As A Decorative Or Protective Coating in Addition To Electronic Potting?

Accepted Answer

Yes. E-132/H-100 is suited for decorative and protective coating applications — not only electronic component encapsulation. Here is what this means for surface coating applications and how it differs from the encapsulation use case.

Question 25

What Is The Difference Between E-132/H-100 And E-700/H-190 For Electronic Potting?

Accepted Answer

E-132/H-100 and E-700/H-190 are both Shore D 80 clear epoxy potting compounds. The differences are specific: E-132 provides a high-gloss non-foggy surface, lower water absorption, higher mechanical strength, and a simpler heat cure schedule. Here is when each formula is the right choice.

Question 26

When Does The Appearance Of A Potted Electronic Assembly Matter Enough To Specify E-132/H-100?

Accepted Answer

E-132/H-100 is specified when the cured epoxy surface must be high-gloss and non-foggy — either because the assembly is visible to the end user, or because the application is a decorative or protective coating. Here is how to identify whether E-132 applies to your application.

Question 27

Is E-120/H-100 Suitable For Wire Coil And Transformer Potting?

Accepted Answer

E-120/H-100 is specified for coil winding and transformer potting applications where cracking under reeling stress is a concern. Shore D 82 hardness, 13,000 psi flexural strength, RT cure without heat equipment. Here is what to evaluate before specifying it for your coil application.

Question 28

What Substrates Does E-120/H-100 Bond To, And What Adhesion Data Is Available?

Accepted Answer

E-120/H-100 bonds to aluminum, iron, and other common electronic assembly substrates. Published lap shear data: aluminum 650 psi, iron 1,010 psi, sanded iron 2,500 psi. Here is what these figures mean for potting and bonding applications.

Question 29

Why Does E-120/H-100 Have Higher Flexural Strength Than Other Clear Epoxy Potting Compounds?

Accepted Answer

E-120/H-100 delivers 13,000 psi flexural strength — the highest in Fong Yong's clear electronic potting range. Here is what that means for coil winding, wire reeling, and applications where cracking resistance after cure matters.

Question 30

How Does The Low Exothermic Reaction in E-120/H-100 Protect Electronic Components During Potting?

Accepted Answer

E-120/H-100 generates low exothermic heat during the curing process — a design feature that protects sensitive electronic components from thermal stress during potting. Here is how exotherm affects potted assemblies and why it matters.

Question 31

Can E-120/H-100 Reach Full Mechanical Performance Without Heat Curing?

Accepted Answer

E-120/H-100 cures fully at room temperature over 7 days, reaching Shore D 82 and 13,000 psi flexural strength without a heat curing step. Here is what the RT cure schedule delivers and when heat cure is worth adding.

Question 32

Why Do Two Epoxy Tables From The Same Formula Look Different After Extended Indoor Use? SEO Metadata

Accepted Answer

A common source of confusion: two tables cast from the same formula, even from the same batch, show noticeably different appearances after extended indoor use. One is still clear. The other has developed an amber tint. The formula was not different. The mixing was done the same way. The difference was created by where each table was placed — and that difference in placement determined the UV-A dose each table received over its service life.

Question 33

Will A Clear Epoxy Table in A Shaded Room Still Yellow Over Time?

Accepted Answer

Placing a clear epoxy table in a room without direct sunlight is the most common approach to reducing UV exposure. It works — but the reduction in UV-A is not always as complete as assumed. A room described as "shaded" can still deliver a real UV-A dose to a table through reflected light, seasonal sun angle changes, and incidental window exposure at certain times of day. What matters is the actual UV-A reaching the table surface, not the general description of the room.

Question 34

Why Does The Wood-Resin Boundary Crack After The Table Has Been in Use?

Accepted Answer

A common report from river table owners: everything looked perfect at completion, but after some time in use, a hairline has appeared along one or both sides where the wood meets the epoxy. The table was not dropped. Nothing visible happened. The crack was not there during the first inspection. This is not a workmanship failure that appeared late. It is a stress accumulation problem — one that develops gradually under cyclic loading that is invisible until it crosses a visible threshold.

Question 35

Does Sunlight Through Windows Actually Cause Epoxy Tables To Yellow?

Accepted Answer

A common assumption is that an indoor table is safe from UV because it is not outdoors. This is not accurate. Sunlight passing through standard glass windows carries UV-A radiation — a specific band of ultraviolet that passes through glass and drives the chemical reaction responsible for epoxy yellowing indoors. The amount of UV-A a table receives depends on its position relative to windows, not on whether it is inside.

Question 36

Can You Reverse Epoxy Yellowing Once It Has Appeared?

Accepted Answer

Once a clear epoxy table has developed visible yellowing, the most common first instinct is to sand and refinish the surface. This does not work. The colour change is not on the surface of the epoxy — it is inside the casting mass. Understanding why surface treatment cannot address internal yellowing is the starting point for deciding what to do next.

Question 37

Does The Epoxy Formula Choice Affect How Much Heat Is Generated During Curing

Accepted Answer

Yes — different epoxy formulas have different exotherm profiles. The rate and peak temperature of heat generation during cure is a formula-level property, not a fixed constant. Formulas designed for thick casting applications have slower, lower-peak exotherm profiles. The 20–25mm layer guideline is a conservative starting estimate for standard clear casting formulas — always confirm from the specific formula's TDS and test on a representative geometry before production pours.

Question 38

I Can See A Crack Forming During The Epoxy Pour — Should I Add More Resin To Fill It?

Accepted Answer

Adding resin to a crack that forms during an epoxy pour does not fix the underlying cause and typically makes it worse. The crack formed because of internal thermal stress — adding more reacting resin adds more heat to a casting that is already thermally overloaded. The correct response is to stop, let the casting cool fully, assess the extent of damage, and revise the layer strategy before any further pours.

Question 39

Will A Thinner Epoxy Layer Still Yellow If I Use A UV-Stable Formula?

Accepted Answer

Thermal yellowing and UV yellowing are two different mechanisms with two different controls. A UV-stable formula eliminates UV-driven yellowing — but does not prevent thermal yellowing if the pour is too deep and the exotherm is not managed. Layer casting controls thermal yellowing. Formula selection controls UV yellowing. Both controls are independent and both are needed for deep castings in window-lit environments.

Question 40

How Do I Know When The Correct Inter-Layer Timing Window Has Been Reached?

Accepted Answer

The inter-layer timing window for layer casting is determined by the surface state of the previous layer — not by the gel time listed on the TDS. The TDS gel time represents full gelation, which is too late for chemical inter-layer bonding. The correct timing is identified by touch: tacky surface, fingerprint holds, no longer liquid.

Question 41

Can I Pour A Deep Epoxy River Channel in One Pour If I Work Quickly And Keep The Mould Cool?

Accepted Answer

Working quickly and cooling the mould does not solve the exotherm problem in a deep epoxy pour. The heat is generated by the chemical curing reaction inside the resin mass itself — not from the ambient environment. Mould cooling helps at the edges; it cannot reach the interior of a large mass. Layer casting is the only reliable thermal control strategy for deep channels.

Question 42

Does Wood Species Affect Which Epoxy Formula To Use For A River Table?

Accepted Answer

Wood species affects surface preparation, tannin content, and moisture behaviour at the wood-resin boundary — all of which are process variables. It does not change the two primary formula selection criteria: UV exposure level and mechanical demand. Species-specific considerations are addressed in the preparation stage, after the formula is selected.

Question 43

What Size River Table Requires A High-Strength Epoxy Formula?

Accepted Answer

There is no single size threshold that triggers a mechanical specification requirement for a river table epoxy fill. But there are practical reference points for when the table geometry shifts epoxy flexural performance from an incidental property to a meaningful specification requirement.

Question 44

Can I Use A UV-Stable Epoxy Formula For A Large River Table in A Shaded Room?

Accepted Answer

You can use a UV-stable formula for a large river table in a shaded room — but the question is whether the UV-stable formula's mechanical properties are sufficient for the span and channel geometry. UV stability and mechanical performance are independent specification axes and must both be evaluated, not assumed to travel together.

Question 45

I Have A Large River Table Going Into A Shaded Room — Do I Still Need A UV-Stable Formula?

Accepted Answer

If a large river table is genuinely going into a shaded interior room with no significant window UV-A reaching the table surface, the formula priority shifts. UV stability moves from the first specification axis to a secondary consideration — and mechanical performance for the table's span and channel geometry becomes the first question to answer.

Question 46

Does Morning Sun Create Enough UV To Yellow An Epoxy Table? | Fong Yong

Accepted Answer

Morning sun through an east-facing window delivers real UV-A to an epoxy table surface. Whether it's enough to matter for formula selection depends on how many hours per day the table is exposed and how close it sits to the glass — not on whether the sunlight feels strong.

Question 47

My River Table Will Be Installed Near Large Windows. Is EC-165 / HC-191 Still Appropriate?

Accepted Answer

EC-165 / HC-191 is designed for shaded indoor environments. If a river table will be installed near large windows or under sustained display lighting, indoor UV exposure may cause standard epoxy to yellow over time. In that case, discuss whether an indoor anti-yellowing formula is more appropriate.

Question 48

How Do I Know Whether My River Table Requires A High-Strength Formula?

Accepted Answer

A high-strength casting system becomes important when the river table has a wide epoxy channel, long unsupported span, or daily-use loading. Geometry and service conditions determine whether flexural strength and elongation should be primary specification criteria.

Question 49

Do You Have Real Customer Project Examples For EC-165 / HC-191 River Tables?

Accepted Answer

Yes. EC-165 / HC-191 has been used in actual customer river table projects with large-slab construction and wide epoxy channels. Exact dimensions should only be stated when recorded, but real project photos are useful evidence that the system is being applied to the type of large indoor table geometry where flexural performance matters.

Question 50

Shore D 80 Vs Shore D 78 — Does A 2-Point Hardness Difference Matter For A Table Top?

Accepted Answer

A 2-point Shore D difference between two epoxy formulas is not a meaningful specification criterion for table top applications. Both Shore D 78 and Shore D 80 represent firmly cured surfaces that resist indentation under normal use. The properties that determine real-world table top performance are flexural strength, elongation, and UV stability — not the last two points on the hardness scale.

Question 51

Large River Table Or Small Low-Load Casting — Does The Formula Change?

Accepted Answer

A large river table and a small low-load casting have different formula requirements. For a small low-load casting, formula selection is driven mainly by water-white appearance, process control, and UV environment. For a large river table, structural performance — flexural strength and elongation across an unsupported span — becomes a primary criterion. Application geometry and UV environment together determine the correct specification.

Question 52

Will Standard Clear Epoxy Yellow Indoors Without Direct Sunlight?

Accepted Answer

Yes. Standard clear epoxy yellows in window-lit indoor environments because window glass passes UV-A radiation (315–400 nm) while blocking UV-B. UV-A is the wavelength that drives photo-oxidation in standard epoxy systems, producing yellow and amber chromophores. Whether your installation requires an anti-yellowing formula depends on the cumulative UV-A dose the surface receives — not simply whether direct sunlight reaches it.

Question 53

Why Is Flexural Strength Important For A River Table Epoxy?

Accepted Answer

A river table is a structural panel — the epoxy fill spans between support points and is under continuous bending stress during daily use. Flexural strength determines how well the cured epoxy resists that load without cracking or transmitting stress to the wood-resin boundary. For large-slab river tables with spans over 1.5 metres, the difference between a 14,000 psi formula and a 4,800 psi alternative is visible over the service life of the table.

Question 54

Why Does White Or Light-Coloured Furniture Show Epoxy Yellowing Earlier Than Dark Wood?

Accepted Answer

Epoxy yellows at the same rate regardless of the substrate colour underneath. What changes is how quickly the yellowing becomes visible. A yellow shift in a clear coating over white furniture is immediately noticeable because the contrast between clear and yellow is high. The same shift over dark walnut is masked by the substrate tone and may not register as a problem for considerably longer. This means yellowing complaints appear earlier on light-coloured surfaces — not because the product failed sooner, but because the visibility threshold was reached sooner.

Question 55

Standard Clear Epoxy Or UV-Stable Formula — Which For My Indoor Table Top?

Accepted Answer

The choice between a standard clear epoxy and a UV-stable anti-yellowing formula for an indoor table top depends on one variable: the UV exposure level of the installation environment. In shaded rooms with minimal window light, a standard formula provides long service life at lower cost. In rooms with south- or east-facing windows, window UV-A is sufficient to yellow standard epoxy within 6 to 18 months, and a UV-stable anti-yellowing formula is the correct specification.

Question 56

How Does Formula Composition Affect Long-Term Clarity in Clear Epoxy?

Accepted Answer

Not all water-clear epoxy resins age at the same rate under indoor UV. The variable is formula composition — specifically, the number of components in the cured matrix that can contribute to UV-driven degradation. A formula with no fillers, no diluents, and no solvents introduces fewer of these components into the cured film. Formula composition is a relevant specification criterion alongside initial clarity and hardness, particularly for installations where long-term appearance retention is required.

Question 57

Can An Anti-Yellowing Epoxy Be Used Outdoors?

Accepted Answer

Indoor anti-yellowing epoxy formulations are rated for window UV-A exposure, not direct outdoor sun. Outdoor UV intensity is 5 to 50 times higher than indoor window UV and includes UV-B radiation and thermal cycling that indoor-grade chemistry is not designed to withstand. Applying an indoor-rated anti-yellowing formula outdoors will produce faster-than-specified yellowing — the product's anti-yellowing performance is calibrated for the indoor UV environment, not for direct sun exposure.

Question 58

Why Does My Clear Epoxy Table Top Turn Yellow After One Year?

Accepted Answer

Clear epoxy table tops yellow indoors because standard epoxy chemistry responds to UV-A radiation (315–400 nm) transmitted through window glass. The discoloration is not a curing failure — it is a photochemical process that accumulates over months of indoor UV exposure. Formula selection at the specification stage is the most effective prevention; a single refinishing cycle on a bonded epoxy surface typically costs more than switching to an anti-yellowing formula at the outset.

Question 59

How Does Ambient Temperature Affect Epoxy Casting Exotherm Risk?

Accepted Answer

Ambient temperature directly affects the starting temperature of the resin mix and the rate of the curing reaction. Higher ambient temperature means the resin starts closer to its peak reaction temperature before the pour. The same pour depth at 30°C generates a significantly higher peak internal temperature than at 20°C. A pour that was manageable in cool workshop conditions can produce cracking, yellowing, or distortion when repeated in summer conditions or a warm environment.

Question 60

What Causes Warping And Distortion in Thick Epoxy Castings?

Accepted Answer

Warping and distortion in thick castings result from uneven cure rates driven by exotherm heat accumulation. When opposite faces or zones of the casting cure at different rates, the differential shrinkage creates internal stress that is held in place by the mold. When the mold is removed, the locked-in stress produces a casting that bows, warps, or shows dimensional variation. The thicker the casting, the more pronounced the cure rate differential and the higher the distortion risk.

Question 61

Why Did My Epoxy Casting Turn Yellow Or Brown After Curing?

Accepted Answer

Yellowing and browning in a clear epoxy casting are thermal discoloration — caused by the internal casting temperature rising above the resin's thermal degradation threshold during the exotherm peak. This can occur even at normal ambient temperatures when the casting volume is large enough to accumulate heat faster than it dissipates. The discoloration is caused by chemical changes in the cured resin matrix and is permanent. Prevention requires controlling pour volume per layer so the peak internal temperature stays within the resin's rated range.

Question 62

Why Does Clear Epoxy Crack After Pouring Into A Thick Mold?

Accepted Answer

Cracking in thick epoxy castings is caused by internal stress from differential cure rates driven by exotherm heat accumulation. The center of the casting cures first and contracts, creating stress in the still-soft outer zones. When those zones harden, they lock in the stress differential. The crack appears when demoulding releases the geometric constraint holding the casting together. Pour volume, ambient temperature, and mold geometry all determine how severe this differential becomes.

Question 63

Can Decorative Composite Panels Be Strong Enough For Light Mechanical Use?

Accepted Answer

Decorative composite panels do have meaningful mechanical properties — fiber reinforcement adds stiffness, impact resistance, and surface hardness beyond the substrate alone. For applications involving incidental mechanical use — covers, housings, light panels — the incidental mechanical properties of a decorative laminate are often sufficient. The distinction is between "strong enough for light handling" and "qualified for defined structural load" — these are different standards that require different validation approaches.

Question 64

Can Clear Epoxy Be Applied Over An Existing Structural Composite Part As A Surface Finish?

Accepted Answer

Applying clear epoxy over a cured structural composite part as a surface finish is a decorative application — the coating is not in the structural load path. The structural composite carries the loads; the clear coat provides optical clarity, UV protection, and surface abrasion resistance. Surface preparation and chemical compatibility with the structural resin system should be verified. The clear coat's mechanical properties do not need to match structural specifications — it is evaluated as a surface coating.

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