diff --git a/include/slg/materials/materialdefs_funcs_generic.cl b/include/slg/materials/materialdefs_funcs_generic.cl
index e454930d0..176347ba0 100644
--- a/include/slg/materials/materialdefs_funcs_generic.cl
+++ b/include/slg/materials/materialdefs_funcs_generic.cl
@@ -160,6 +160,7 @@ OPENCL_FORCE_INLINE float SchlickDistribution_G(const float roughness, const flo
 }
 
 OPENCL_FORCE_INLINE float GetPhi(const float a, const float b) {
+	if ((a < DEFAULT_EPSILON_MIN) || (b < DEFAULT_EPSILON_MIN)) return 0.f;
 	return M_PI_F * .5f * sqrt(a * b / (1.f - a * (1.f - b)));
 }
 
@@ -254,13 +255,13 @@ OPENCL_FORCE_INLINE float3 SchlickBSDF_CoatingSampleF(const float3 ks,
 	const float cosWH = dot(fixedDir, wh);
 	*sampledDir = 2.f * cosWH * wh - fixedDir;
 
-	if ((fabs((*sampledDir).z) < DEFAULT_COS_EPSILON_STATIC) || (fixedDir.z * (*sampledDir).z < 0.f))
+	if ((fabs((*sampledDir).z) < DEFAULT_COS_EPSILON_STATIC))
 		return BLACK;
 
 	const float coso = fabs(fixedDir.z);
 	const float cosi = fabs((*sampledDir).z);
 
-	*pdf = specPdf / (4.f * cosWH);
+	*pdf = specPdf / (4.f * fabs (cosWH));
 	if (*pdf <= 0.f)
 		return BLACK;
 
diff --git a/include/slg/materials/materialdefs_funcs_glossy2.cl b/include/slg/materials/materialdefs_funcs_glossy2.cl
index 391cbb0d0..dec433ef1 100644
--- a/include/slg/materials/materialdefs_funcs_glossy2.cl
+++ b/include/slg/materials/materialdefs_funcs_glossy2.cl
@@ -76,19 +76,6 @@ OPENCL_FORCE_INLINE void Glossy2Material_Evaluate(__global const Material* restr
 	const float3 kdVal = Texture_GetSpectrumValue(material->glossy2.kdTexIndex, hitPoint TEXTURES_PARAM);
 
 	const float3 baseF = Spectrum_Clamp(kdVal) * M_1_PI_F * fabs(lightDir.z);
-	if (eyeDir.z <= 0.f) {
-		// Back face: no coating
-
-		const float directPdfW = fabs(sampledDir.z * M_1_PI_F);
-		const BSDFEvent event = DIFFUSE | REFLECT;
-		const float3 result = baseF;
-
-		EvalStack_PushFloat3(result);
-		EvalStack_PushBSDFEvent(event);
-		EvalStack_PushFloat(directPdfW);
-
-		return;
-	}
 
 	// Front face: coating+base
 	const BSDFEvent event = GLOSSY | REFLECT;
@@ -132,7 +119,7 @@ OPENCL_FORCE_INLINE void Glossy2Material_Evaluate(__global const Material* restr
 	const float3 S = FresnelSchlick_Evaluate(ks, fabs(dot(sampledDir, H)));
 
 	const float3 coatingF = SchlickBSDF_CoatingF(ks, roughness, anisotropy, material->glossy2.multibounce,
-			fixedDir, sampledDir);
+			fixedDir, sampledDir); 
 
 	// Blend in base layer Schlick style
 	// assumes coating bxdf takes fresnel factor S into account
@@ -161,25 +148,6 @@ OPENCL_FORCE_INLINE void Glossy2Material_Sample(__global const Material* restric
 
 	const float3 kdVal = Texture_GetSpectrumValue(material->glossy2.kdTexIndex, hitPoint TEXTURES_PARAM);
 
-	if (fixedDir.z <= 0.f) {
-		// Back Face
-		float pdfW;
-		const float3 sampledDir = -1.f * CosineSampleHemisphereWithPdf(u0, u1, &pdfW);
-		if (fabs(CosTheta(sampledDir)) < DEFAULT_COS_EPSILON_STATIC) {
-			MATERIAL_SAMPLE_RETURN_BLACK;
-		}
-		
-		const BSDFEvent event = DIFFUSE | REFLECT;
-		const float3 result = Spectrum_Clamp(kdVal);
-		
-		EvalStack_PushFloat3(result);
-		EvalStack_PushFloat3(sampledDir);
-		EvalStack_PushFloat(pdfW);
-		EvalStack_PushBSDFEvent(event);
-
-		return;
-	}
-
 	const float3 ksVal = Texture_GetSpectrumValue(material->glossy2.ksTexIndex, hitPoint TEXTURES_PARAM);
 	float3 ks = ksVal;
 	const float i = Texture_GetFloatValue(material->glossy2.indexTexIndex, hitPoint TEXTURES_PARAM);
@@ -192,8 +160,8 @@ OPENCL_FORCE_INLINE void Glossy2Material_Sample(__global const Material* restric
 	const float nuVal = Texture_GetFloatValue(material->glossy2.nuTexIndex, hitPoint TEXTURES_PARAM);
 	const float nvVal = Texture_GetFloatValue(material->glossy2.nvTexIndex, hitPoint TEXTURES_PARAM);
 
-	const float u = clamp(nuVal, 1e-9f, 1.f);
-	const float v = clamp(nvVal, 1e-9f, 1.f);
+	const float u = clamp(nuVal, 1e-5f, 1.f);
+	const float v = clamp(nvVal, 1e-5f, 1.f);
 	const float u2 = u * u;
 	const float v2 = v * v;
 	const float anisotropy = (u2 < v2) ? (1.f - u2 / v2) : u2 > 0.f ? (v2 / u2 - 1.f) : 0.f;
@@ -207,18 +175,13 @@ OPENCL_FORCE_INLINE void Glossy2Material_Sample(__global const Material* restric
 	float basePdf, coatingPdf;
 	float3 baseF, coatingF;
 	if (passThroughEvent < wBase) {
-		// Sample base BSDF (Matte BSDF)
-		baseF = Spectrum_Clamp(kdVal);
-		if (Spectrum_IsBlack(baseF)) {
-			MATERIAL_SAMPLE_RETURN_BLACK;
-		}
 		
 		sampledDir = (signbit(fixedDir.z) ? -1.f : 1.f) * CosineSampleHemisphereWithPdf(u0, u1, &basePdf);
-		if (fabs(CosTheta(sampledDir)) < DEFAULT_COS_EPSILON_STATIC) {
+		if (fabs(sampledDir.z) < DEFAULT_COS_EPSILON_STATIC) {
 			MATERIAL_SAMPLE_RETURN_BLACK;
 		}
 
-		baseF *= basePdf;
+		baseF = Spectrum_Clamp (kdVal) * M_1_PI_F * fabs(sampledDir.z);
 
 		// Evaluate coating BSDF (Schlick BSDF)
 		coatingF = SchlickBSDF_CoatingF(ks, roughness, anisotropy, material->glossy2.multibounce,
@@ -232,7 +195,7 @@ OPENCL_FORCE_INLINE void Glossy2Material_Sample(__global const Material* restric
 			MATERIAL_SAMPLE_RETURN_BLACK;
 		}
 
-		const float absCosSampledDir = fabs(CosTheta(sampledDir));
+		const float absCosSampledDir = fabs(sampledDir.z);
 		if (absCosSampledDir < DEFAULT_COS_EPSILON_STATIC) {
 			MATERIAL_SAMPLE_RETURN_BLACK;
 		}
@@ -241,7 +204,7 @@ OPENCL_FORCE_INLINE void Glossy2Material_Sample(__global const Material* restric
 
 		// Evaluate base BSDF (Matte BSDF)
 		basePdf = absCosSampledDir * M_1_PI_F;
-		baseF = Spectrum_Clamp(kdVal) * basePdf;
+		baseF = Spectrum_Clamp(kdVal) * M_1_PI_F * absCosSampledDir; 
 	}
 
 	const BSDFEvent event = GLOSSY | REFLECT;
diff --git a/src/slg/materials/glossy2.cpp b/src/slg/materials/glossy2.cpp
index 62c08173c..1ad54b5f3 100644
--- a/src/slg/materials/glossy2.cpp
+++ b/src/slg/materials/glossy2.cpp
@@ -49,18 +49,6 @@ Spectrum Glossy2Material::Evaluate(const HitPoint &hitPoint,
 	const Vector &localSampledDir = hitPoint.fromLight ? localEyeDir : localLightDir;
 
 	const Spectrum baseF = Kd->GetSpectrumValue(hitPoint).Clamp(0.f, 1.f) * INV_PI * fabsf(localLightDir.z);
-	if (localEyeDir.z <= 0.f) {
-		// Back face: no coating
-
-		if (directPdfW)
-			*directPdfW = fabsf(localSampledDir.z * INV_PI);
-
-		if (reversePdfW)
-			*reversePdfW = fabsf(localFixedDir.z * INV_PI);
-
-		*event = DIFFUSE | REFLECT;
-		return baseF;
-	}
 
 	// Front face: coating+base
 	*event = GLOSSY | REFLECT;
@@ -81,34 +69,19 @@ Spectrum Glossy2Material::Evaluate(const HitPoint &hitPoint,
 	const float roughness = u * v;
 
 	if (directPdfW) {
-		if (localFixedDir.z < 0.f) {
-			// Backface
-			*directPdfW = fabsf(localSampledDir.z * INV_PI);
-		} else {
-			const float wCoating = SchlickBSDF_CoatingWeight(ks, localFixedDir);
-			const float wBase = 1.f - wCoating;
-
-			*directPdfW = wBase * fabsf(localSampledDir.z * INV_PI) +
-				wCoating * SchlickBSDF_CoatingPdf(roughness, anisotropy, localFixedDir, localSampledDir);
-		}
+		const float wCoating = SchlickBSDF_CoatingWeight(ks, localFixedDir);
+		const float wBase = 1.f - wCoating;
+
+		*directPdfW = wBase * fabsf(localSampledDir.z * INV_PI) +
+			wCoating * SchlickBSDF_CoatingPdf(roughness, anisotropy, localFixedDir, localSampledDir);
 	}
 
 	if (reversePdfW) {
-		if (localSampledDir.z < 0.f) {
-			// Backface
-			*reversePdfW = fabsf(localFixedDir.z * INV_PI);
-		} else {
-			const float wCoatingR = SchlickBSDF_CoatingWeight(ks, localSampledDir);
-			const float wBaseR = 1.f - wCoatingR;
-
-			*reversePdfW = wBaseR * fabsf(localFixedDir.z * INV_PI) +
-				wCoatingR * SchlickBSDF_CoatingPdf(roughness, anisotropy, localSampledDir, localFixedDir);
-		}
-	}
+		const float wCoatingR = SchlickBSDF_CoatingWeight(ks, localSampledDir);
+		const float wBaseR = 1.f - wCoatingR;
 
-	if (localFixedDir.z < 0.f) {
-		// Backface, no coating
-		return baseF;
+		*reversePdfW = wBaseR * fabsf(localFixedDir.z * INV_PI) +
+			wCoatingR * SchlickBSDF_CoatingPdf(roughness, anisotropy, localSampledDir, localFixedDir);
 	}
 
 	// Absorption
@@ -137,20 +110,6 @@ Spectrum Glossy2Material::Sample(const HitPoint &hitPoint,
 	if (fabsf(localFixedDir.z) < DEFAULT_COS_EPSILON_STATIC)
 		return Spectrum();
 
-	if (localFixedDir.z <= 0.f) {
-		// Back face
-		*localSampledDir = -CosineSampleHemisphere(u0, u1, pdfW);
-
-		const float absCosSampledDir = fabsf(localSampledDir->z);
-		if (absCosSampledDir < DEFAULT_COS_EPSILON_STATIC)
-			return Spectrum();
-		*event = DIFFUSE | REFLECT;
-		if (hitPoint.fromLight)
-			return Kd->GetSpectrumValue(hitPoint) * fabsf(localFixedDir.z / absCosSampledDir);
-		else
-			return Kd->GetSpectrumValue(hitPoint);
-	}
-
 	Spectrum ks = Ks->GetSpectrumValue(hitPoint);
 	const float i = index->GetFloatValue(hitPoint);
 	if (i > 0.f) {
@@ -159,15 +118,15 @@ Spectrum Glossy2Material::Sample(const HitPoint &hitPoint,
 	}
 	ks = ks.Clamp(0.f, 1.f);
 
-	const float u = Clamp(nu->GetFloatValue(hitPoint), 1e-9f, 1.f);
-	const float v = Clamp(nv->GetFloatValue(hitPoint), 1e-9f, 1.f);
+	const float u = Clamp(nu->GetFloatValue(hitPoint), 1e-5f, 1.f);
+	const float v = Clamp(nv->GetFloatValue(hitPoint), 1e-5f, 1.f);
 	const float u2 = u * u;
 	const float v2 = v * v;
 	const float anisotropy = (u2 < v2) ? (1.f - u2 / v2) : u2 > 0.f ? (v2 / u2 - 1.f) : 0.f;
 	const float roughness = u * v;
 
 	// Coating is used only on the front face
-	const float wCoating = SchlickBSDF_CoatingWeight(ks, localFixedDir);
+	const float wCoating = SchlickBSDF_CoatingWeight (ks, localFixedDir);
 	const float wBase = 1.f - wCoating;
 
 	float basePdf, coatingPdf;
@@ -247,29 +206,19 @@ void Glossy2Material::Pdf(const HitPoint &hitPoint,
 	const float roughness = u * v;
 
 	if (directPdfW) {
-		if (localFixedDir.z < 0.f) {
-			// Backface
-			*directPdfW = fabsf(localSampledDir.z * INV_PI);
-		} else {
-			const float wCoating = SchlickBSDF_CoatingWeight(ks, localFixedDir);
-			const float wBase = 1.f - wCoating;
-
-			*directPdfW = wBase * fabsf(localSampledDir.z * INV_PI) +
-				wCoating * SchlickBSDF_CoatingPdf(roughness, anisotropy, localFixedDir, localSampledDir);
-		}
+		const float wCoating = SchlickBSDF_CoatingWeight(ks, localFixedDir);
+		const float wBase = 1.f - wCoating;
+
+		*directPdfW = wBase * fabsf(localSampledDir.z * INV_PI) +
+			wCoating * SchlickBSDF_CoatingPdf(roughness, anisotropy, localFixedDir, localSampledDir);
 	}
 
 	if (reversePdfW) {
-		if (localSampledDir.z < 0.f) {
-			// Backface
-			*reversePdfW = fabsf(localFixedDir.z * INV_PI);
-		} else {
-			const float wCoatingR = SchlickBSDF_CoatingWeight(ks, localSampledDir);
-			const float wBaseR = 1.f - wCoatingR;
-
-			*reversePdfW = wBaseR * fabsf(localFixedDir.z * INV_PI) +
-				wCoatingR * SchlickBSDF_CoatingPdf(roughness, anisotropy, localSampledDir, localFixedDir);
-		}
+		const float wCoatingR = SchlickBSDF_CoatingWeight(ks, localSampledDir);
+		const float wBaseR = 1.f - wCoatingR;
+
+		*reversePdfW = wBaseR * fabsf(localFixedDir.z * INV_PI) +
+			wCoatingR * SchlickBSDF_CoatingPdf(roughness, anisotropy, localSampledDir, localFixedDir);
 	}
 }
 
diff --git a/src/slg/materials/material.cpp b/src/slg/materials/material.cpp
index 072ac377d..e6f6222fa 100644
--- a/src/slg/materials/material.cpp
+++ b/src/slg/materials/material.cpp
@@ -423,6 +423,7 @@ float slg::SchlickDistribution_G(const float roughness, const Vector &localFixed
 }
 
 static float GetPhi(const float a, const float b) {
+	if ((a < DEFAULT_EPSILON_MIN) || (b < DEFAULT_EPSILON_MIN)) return 0.f;
 	return M_PI * .5f * sqrtf(a * b / (1.f - a * (1.f - b)));
 }
 
@@ -506,13 +507,13 @@ Spectrum slg::SchlickBSDF_CoatingSampleF(const bool fromLight, const Spectrum ks
 	const float cosWH = Dot(localFixedDir, wh);
 	*localSampledDir = 2.f * cosWH * wh - localFixedDir;
 
-	if ((fabsf(localSampledDir->z) < DEFAULT_COS_EPSILON_STATIC) || (localFixedDir.z * localSampledDir->z < 0.f))
+	if ((fabsf (localSampledDir->z) < DEFAULT_COS_EPSILON_STATIC))
 		return Spectrum();
 
 	const float coso = fabsf(localFixedDir.z);
 	const float cosi = fabsf(localSampledDir->z);
 
-	*pdf = specPdf / (4.f * cosWH);
+	*pdf = specPdf / (4.f * fabs (cosWH));
 	if (*pdf <= 0.f)
 		return Spectrum();