Epoxy resins

We have provided information which present the results from various measurements on the commonly used resins, together with comments on their suitability and advice on sample preparation.

The withdrawal of the Ciba-Geigy resin Araldite MY 778 and Hardener HY 951 from the market in 2007 required us to re-look at the most suitable epoxy resins to use for Secondary Ion Mass Spectrometry (SIMS) analysis.

Suppliers

Over 90% of the samples studied by the facility are embedded in, or mounted with, one of the commonly available resins. Ideally, these resins should have a low viscosity, set quickly, set hard, be compatible at high vacuum and contain no element that will compromise the SIMS chemical or isotopic analysis. In addition, they should be suitable for petrological study, imaging (e.g. cathodoluminescence (CL), backscatter electron (BSE)) and electron micro-probe analysis (EPMA).

We have provided information which present the results from various measurements on the commonly used resins, together with comments on their suitability and advice on sample preparation.

Any additional information or comments concerning these, or other epoxy resins are welcome and should be addressed to the Ion-Microprobe Facility.

Epoxy Resins Tested

Buehler:

EpoThin
EpoHeat
EpoxiCure
TransOptic (not an epoxy resin, but a fine-grained thermoplastic)
ProbeMet (not an epoxy resin, but an epoxy mounting compound with copper filler)
KonductoMet (not an epoxy resin, but a Phenolic mounting compound with graphite filler)

Struers:

SpeciFix-20
EpoFix

Others:

Ciba Geigy MY 778 & HY 951
Robnor Resins PX771c (previously CY1301 & HY1300)
Korapox 439
Domestic Rapid-set Araldite (Partial Tests Only)
Domestic Araldite (Partial Tests Only)
Varian Torr Seal (Partial Tests Only)
Petropoxy

We have gathered information from respective supplier web sites, data sheets and catalogues.

Detailed information on the physical and chemical properties of the resins was not available from any of the suppliers. We have provided a limited compilation below, which is a summary obtained from multiple sources.

Notes on viscosity:

The unit most used is the centipoise (cP), which is 0.01 poise (P). The everyday fluids listed below have viscosities between 0.3 and 250,000 cP.

Acetone, 0.3
Water, 1.0
Olive oil, 84
Motor oil, 125
Glycerine, 1490
Maple syrup, 3200
Treacle, 20,000
Peanut butter, 250,000

Notes on hardness:

There are many scales used in the measurement of hardness e.g. Vickers, Brinell, Rockwell, Shore, Knoop etc. The unit most frequently used for resins is the Shore D scale. Some values from every day objects (apart from Indium!) are listed below.

Perspex, 87.8 +/- 0.12
PVC, 81.1 +/- 0.47
Indium, 29.5 +/- 0.42
Yellow BIC biro case, 81.5 +/- 0.25

Suppliers information

Epoxy Resin	Viscosity	Hardness (Shore D)	Cure Time	Shrinkage	Manufacturers Comments
EpoThin	Low - 200-350cps at 25'C	78	9 Hours	Not Supplied	Good penetration of voids during vacuum impregnation; Good for heat sensitive specimens
EpoHeat	Low - 32 cps at 80'C	85	90 Minutes	Not Supplied	Fast, heat cure epoxy system with low shrinkage. Excellent for vacuum impregnation
EpoxiCure	400-600 cps	82	6 Hours	Low	General purpose epoxy, good adherence to specimen, good for heat sensitive specimens
TransOptic	N/A	Average		Some, small	Fine grained thermoplastic, applications - transparent embedding, targeted preparation, embedding sensitive samples
ProbeMet	N/A	Not Supplied		None	Epoxy mounting compound, with copper thermosetting filler, conductive. Applications - SEM-applications and Electrolytic polishing
KonductoMet	N/A	Not Supplied		Some, small	Phenolic mounting compound with graphite thermosetting filler, conductive, Application - SEM-applications and Electrolytic polishing
SpeciFix-20	Not Supplied	84	8 Hours	None	Especially suited for vacuum impregnation
EpoFix	Very low	78	12 Hours	None	Especially suited for vacuum impregnation
Ciba Geigy MY778 & HY951	Low - 4-8 Poises at 21oC	Not Supplied	24 Hours	None	Good mechanical strength,resistant to chemical attack, excellent electrical properties
Robnor Resins PX771c	Low - 600 mPas	85	48 Hours	None	Excellent insulation characteristics, RoHS and WEEE compliant
Korapox 439	1500 mPas	Not Supplied	24 Hours	None	Good resistance to humidity and weathering
Domestic Rapid Set Araldite	Not Supplied	Not Supplied	Not Supplied	Not Supplied	Not Supplied
Domestic Araldite	Not Supplied	Not Supplied	Not Supplied	Not Supplied	Not Supplied
Varian Torr Seal	Not Supplied	Not Supplied	2 Hours at 220'C	Not Supplied	Low Vapour-Pressure Epoxy Resin Sealant. Solvent-free and can be used at pressures of 10-9 torr or below and at temperatures of -45 °C to +120 °C. Bonds with many materials, including metals, ceramics, and glass.
Petropoxy	Low	Not Supplied	10 Minutes at 135 - 140'C	Not Supplied	Especially developed for use in the preparation of petrographic thin sections, only needs mixing once every 5 days

Links to suppliers websites

We have provided sample resin preparation procedures for your reference.

The samples were prepared as close as possible to the manufacturers recommendations and all were cut, washed and dried in an identical manner. After preparation the samples were stored in a desiccator prior to analysis and testing.

Epoxy Resin	Resin Mix Ratio By Weight	Cure Temperature	Cure Time	Cutting & Grinding	Cleaning	Example
EpoThin	100:39	Room Temperature	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
EpoHeat	4:1	55'C	1.5hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
EpoxiCure	5:1	Room Temperature	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
EpoxiCure	6:1	Room Temperature then 65'C	4hr at 21'C then 2hr at 65'C	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
TransOptic	N/A	180'C at 290Bar for 17 min	24hr	As formed	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
ProbeMet	N/A	150'C at 290Bar for 4 min	24hr	As formed	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
KonductoMet	N/A	150'C at 290Bar for 4 min	24hr	As formed	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
SpeciFix-20	7:1	Room Temperature	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
EpoFix	25:3	Room Temperature	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Ciba Geigy MY778 & HY951	10:1	Room Temperature	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Robnor Resins PX771c	3:03:1	Room Temperature	48hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Korapox 439	2:1	Room Temperature	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Domestic Rapid Set Araldite	1:1 Visual	Room Temperature	-	Poured into 25mm x 5mm Al ring	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Domestic Araldite	1:1 Visual	Room Temperature	-	Poured into 25mm x 5mm Al ring	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Varian Torr Seal	1:1 Visual	Room Temperature	-	Poured into 25mm x 5mm Al ring	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image
Petropoxy	100:1	135'C	24hr	Diamond saw with water. Diamond Lap (Buehler UltraPrep) with water	Washed Ultrasonic Clean with 10% Decon 90 Rinsed with Deionised Water Two Ultrasonic Cleans with Deionised Water Dried at 50'C for 2hr	Image

Testing and results

Information on testing various measurements on the commonly used resins, together with comments on their suitability and advice on sample preparation.

We recommend the use of EpoxiCure, SpeciFix-20 or EpoFix for SIMS analysis.

The quality of the bond between the epoxy resin and the mineral grains is important if the minerals are going to remain embedded during the grinding and polishing process.

Furthermore, to achieve a good conducting path across the sample, the resin must have good mechanical contact with the grains. This electrical conductivity, formed by either C-evaporation or Au-sputtering, is an essential part of the sample preparation before SIMS or EPMA analysis.

This bonding, or shrinkage, has been investigated by looking at the interface between embedded glass spheres and the resin, as well as the resin relationship with its surrounding Al-ring. It is readily acknowledged that this test is rather subjective. Nevertheless, some general observations can be made.

Sample Preparation

Samples of 10 resins were mounted together with approximately thirty, 1.5-2.5mm glass balls (VWR, Product number 332134Y) in individual 25mm diameter, 5mm deep, Al-rings. The three Beuhler hot press resins; TransOptic, ProbeMet and KonductoMet were mounted with the glass balls but without the Al-rings. The remaining three; Araldite, Araldite quick set and Varian Torr Seal were mounted in Al-rings without the glass balls.

The 13 mounts containing glass balls were then ground so a section could be seen through the balls using Beuhler UltraPrep nickel bonded diamond 74 micron and 20 micron discs followed by 1200 and 2500 silicon carbide paper. They were polished with 3 micron diamond for 15 minutes and then with 0.3 micron Al-oxide for 10 minutes, washed and then ultrasonically cleaned with 10% Decon 90. All of the resins were treated in an identical manner and were all polished together on the same cloth. The samples were finally cleaned with ethanol before carbon coating using a Deton coater to produce a thin conducting film across the sample surface.

Bonding

The resin's bonding to the glass balls was examined by an optical microscope (Leica DM***) in reflected light. The images presented are representative of the sample. The gap between the glass and the epoxy was then confirmed and accurately measured using a Philips XL30CP Scanning electron Microscope, in secondary electron imaging mode. Again, the gaps quoted and images recorded are believed to be representative of the sample concerned.

Epoxy Resin	Typical Gap Measurements
EpoThin	1.96um 6.66um 4.49um
EpoHeat	11.93um 11.30um 12.70um
EpoxiCure (Cured at Room Temperature)	1.02 0.96 0.72
EpoxiCure (cured at 65'C)	7.32um 8.54um 6.16um
TransOptic	6.01um 4.52um 1.55um
ProbeMet	Difficult to measure due to imhomogeneity of material
KonductoMet	Difficult to measure due to imhomogeneity of material
SpeciFix-20	2.92um 2.40um 3.20um
EpoFix	Very difficult to measure all < 1.00
Ciba Geigy MY778 & HY951	0.52 0.49 0.68
Robnor Resins PX771c	3.18um 2.80um 3.63um
Korapox 439	1.68um 1.77um 1.59um
Petropoxy	1.00um 0.67um 0.34um

Polishing Relief

The effect of polishing was investigated by measuring the difference in height between the epoxy resin and adjacent glass balls. The measurement was made using a Tencor alpha-step 200 profileometer. The position of the glass-epoxy interface was confirmed by optical microscopy. All of the resins were polished together on the same cloth, at the same time, for the same duration. The profile(s) presented are believed to be representative of the sample.

Epoxy Resin	Typical Relief Measurements	Profile
EpoThin	5.9um 5.4um 4.6um	Document tencorethin (665 KB / DOC)
EpoHeat	5.0um 4.8um 3.9um	Document tencoreheat (36.5 KB / DOC)
EpoxiCure (Room Temperature)	1.8um 1.7um 1.7um	Document tencorecurert (36.5 KB / DOC)
EpoxiCure 65'C	2.9um 2.7um 2.8um	Document tencorecure65 (40.5 KB / DOC)
TransOptic	5.1um 6.0um 5.8um	Document tencortopt (87 KB / DOC)
ProbeMet	2.0um 1.5um 1.2um	Document tencorpmet (112 KB / DOC)
KonductoMet	1.5um 1.0um 0.5um	Document tencorkmet (124 KB / DOC)
SpeciFix-20	1.5um 1.4um 1.3um	Document tencorsfx (39.5 KB / DOC)
EpoFix	1.8um 1.9um 1.7um	Document tencorefx (33 KB / DOC)
Ciba Geigy MY778 & HY951	2.2um 1.7um 1.6um	Document tencorciba (38.5 KB / DOC)
Robnor Resins PX771c	1.9um 1.8um 1.7um	Document tencorrob (89.5 KB / DOC)
Korapox 439	5.3um 5.9um 5.5um	Document tencorkpx (108.5 KB / DOC)
Petropoxy	2.9um 2.6um 2.5um	Document tencorpet (34.5 KB / DOC)

When bombarded with high energy electrons, epoxy resins give off light in the visible region of the spectrum. This light can dominate the cathodoluminescence of some minerals and should be minimised or eliminated.

Sample preparation

Ten of the resins were mounted into a specially made aluminium block with twenty, 2mm holes, each hole being filled with a different resin. The resins were mixed and cured according to the manufacturer's specification by first mounting the high temperature cure resins followed by the cold cure, allowing sufficient cure time. There was no post cure heating of any of the resins. Zircon and apatite crystals were also mounted to compare their cathodoluminescence with the resins. The zircon (91500) was mounted in epothin and the apatite (Durango) in SpeciFix, Araldite, Araldite rapid set, Varian Torr Seal and the Beuhler hot press mounts were not tested.

The Al-mount was then ground using 1200, 2500 and 4000 silicon carbide paper with water. It was then polished with 6, 3 and 1 micron diamond (Buehler Metadi Supreme diamond suspension) and then washed and ultrasonically cleaned with Pet-ether (Product spec). The samples were finally cleaned with ethanol prior to carbon coating using a Denton (BTT-IV) coater to produce a thin conducting film across the sample surface.

Analytical Procedure

The cathodoluminescence of the resins were measured using a Philips XL30CP Scanning Electron Microscope (SEM) with a KE-cathodoluminescence detector. All images were acquired at 20kV and a beam current of 5nA measured in a Faraday cup using a Keithley picoammeter (model 486).

Image acquisition time was 32.5 seconds. The grey level was adjusted so that a fragment of 91500 zircon mounted in a block of Epothin gave a white level of 256 on the zircon and a grey level of 0 on the Al sample holder. The contrast and brightness were not adjusted after this calibration. An image of each resin was acquired under identical instrumental conditions in a single slow scan.

Only areas that were void of bubbles and were representative of the sample were selected for grey level analysis. The analysis was conducted using XL-Docu whereby an average of 230 pixels were selected in the centre of resin from which an average was calculated.

Results

Epoxy Resin	Average Grey Value (0-255)	Cathodoluminescence Image
Petropoxy	18	Image
EpoxiCure (Cured at 55'C)	58	Image
EpoThin	69	Image
EpoFix	82	Image
EpoHeat	86	Image
Ciba Geigy; MY778 & HY951	127	Image
SpeciFix-20	144	Image
Robnor Resin PX771c	255	Image
Korapox 439	255	Image
Zircon (mounted in EpoThin)	255	Image
Apatite (mounted in SpeciFix 20)	255	Image

Samples of 13 resins were mounted together with approximately ten, 1.5-2.5mm glass balls (VWR, Product number 332134Y) in individual 25mm diameter, 5mm deep, Al-rings. The remaining three; Araldite, Araldite rapid-set and Varian Torr Seal were mounted in Al-rings without the glass balls.

X-Ray analysis: sample preparation

All 13 mounts were then ground so a section could be seen through the balls using Beuhler UltrPrep nickel bonded diamond 74 micron and 20 micron discs followed by 1200 and 2500 silicon carbide paper. They were polished with 3 micron diamond for 15 minutes and then 0.3 micron Al-oxide for 10 minutes, washed and then ultrasonically cleaned with 10% Decon 90. The samples were finally cleaned with ethanol prior to carbon coating using a Deton coater to produce a thin conducting film across the sample surface.

All samples were treated identically and following the routine grinding and polishing procedures used at the University of Edinburgh.

X-Ray analytical conditions

Energy dispersive X-ray analysis of the resins was performed using a Philips XL30CP with PGT Spirit X-ray analysis software. The X-ray spectra were collected for a live time of 600 seconds using a 20Kv, 5nA current measured with a Faraday Cup and Keithley picoamplifier (Model 486).

All the X-ray spectra may be downloaded, provided as a Word document:

Spectrum report (519.5 KB / DOC)

X-ray results

Epoxy Resin	EDS Spectra	Comments
EpoThin	Document Epothin Report (41.5 KB / DOC)	X-Ray spectra show high C, O and moderate Cl concentrations
EpoHeat	Document Epoheat (43 KB / DOC)	X-Ray spectra show high C, Si, Cl and moderate O concentrations
EpoxiCure RT	Document Epoxicure RT (42.5 KB / DOC)	X-Ray spectra show high C, O and Cl
EpoxiCure 65	Document epoxicure 65 (41.5 KB / DOC)	X-Ray spectra show high C, O and Cl
TransOptic	Document Transoptic (65.5 KB / DOC)	X-Ray spectra show high C and O concentrations, by far the cleanest spectra
ProbeMet	Document ProbeMet (68.5 KB / DOC)	Composition highly variable. Contains fragments of Si and Cu.
KonductoMet	Document Konductmet (62 KB / DOC)	Composition highly variable. Contains fragments of C and Si with O, Al, Cl, Na and S
SpeciFix-20	Document Specifix (44 KB / DOC)	X-Ray spectra show high C, O and Cl, as well as Si and S
EpoFix	Document Epofix (42 KB / DOC)	X-Ray spectra show C, O and Cl
Ciba Geigy MY778 & HY951	Document Ciba Geigy (42.5 KB / DOC)	X-Ray spectra show high C, O and Cl
Robnor Resins PX771c	Document Robner Resin (42.5 KB / DOC)	X-Ray spectra show high C, O and Si
Korapox 439	Document Korapox report (42.5 KB / DOC)	X-Ray spectra shows high C, O, Si, and Cl
Domestic Rapid set Araldite	Document Araldite (66.5 KB / DOC)	X-Ray spectra variable significant S levels and C, O, Al and Cl
Domestic Araldite	Document Araldite Slow (42.5 KB / DOC)	X-Ray spectra show high C, O and Si with small amount of Cl
Varian Torr Seal	Document Varian (67.5 KB / DOC)	X-Ray spectra show significant amounts of C, O, Mg, Si, S and Ca as well as Cl, k, Ti, Na and Al.
Petropox	Document Petropoxy (43 KB / DOC)	X-Ray spectra show large amounts of C and O as well as F, Si and Cl

SIMS analysis: sample preparation

Secondary Ion Mass Spectrometry (SIMS) analysis was performed on the all 13 resins mounted in two blocks together with 3 separate 25mm diameter blocks. All samples were ground and polished using the procedure outlined above, then coated with a ~30nm layer of gold, and pre-pumped in the instruments air-lock for >12hrs prior to analysis.

SIMS analytical procedure: positive ions

The analyses were performed using a Cameca ims-4f at the University of Edinburgh using a 5nA, O- primary beam with a net impact energy of ~14KeV. High energy (75eV +/20eV) positive secondary ions were extracted and detected by an electron multiplier.

SIMS results: positive ions

A subset of the analysed species is presented below. The complete data set is available for Excel:

SIMS Results Positive Ions (715 KB / XLS)

Avg Cps	7Li	11B	23Na	27Al	30Si	39K	40Ca	56Fe
Araldite	10.1	200.6	8424.8	9318.7	37.9	2414	556.9	9.3
Ciba-Geigy	0.3	0.1	341.1	68.6	1.8	76.6	90.9	1.0
Epofix	1.3	0.0	424.6	12.5	1.2	88.5	104.3	0.6
Epoheat	0.0	0.0	180.1	167.0	1.1	127.3	24.6	5.1
Epotech	0.3	0.4	259.9	77.4	1.3	47.0	89.0	22.5
Epothin	1.8	0.1	419.3	78.4	0.6	84.4	125.1	1.0
Epoxicure (65)	0.1	0.3	208.4	43.8	1.5	89.5	22.1	5.0
Epoxicure (RT)	0.1	0.3	225.5	24.1	1.0	87.5	16.9	4.8
Konductomet 1	673.6	33.9	56253.9	111765.7	1301.7	6021.4	339154	3206.7
Konductomet 2	399.9	55.4	3638.8	122379.9	1808.3	4399.9	10249.0	2850.9
Korapox	1.0	0.0	316.8	51.5	47.4	101.9	32.1	4.9
Petropoxy	0.6	4140.5	2338.7	66.0	0.1	226.8	121.0	1.6
Probemet 1	126.3	1.6	1924.7	13690.9	25036.9	1411.5	21510.3	2222.8
Probemet 2	29.4	4.1	188.4	11213.2	266174.3	495.3	523.6	5334.4
Robnor	0.4	0.1	266.0	90.4	0.5	76.3	17.0	5.9
Specifix 1	5.5	0.0	330.1	14.0	60.5	55.8	79.6	0.8
Specifix 2	5.8	0.1	325.3	18.5	70.0	57.0	72.1	0.8
Transoptic	0.0	0.0	183.5	272.4	0.1	46.1	38.0	4.1
Varian	5939.6	12384.0	29995.3	27368.6	123524.6	9921.8	453257.0	5025.2

SIMS analytical procedure: negative ions

The analyses were performed using a Cameca ims-4f at the University of Edinburgh using a 5nA, O- primary beam with a net impact energy of ~5.5KeV. High energy (50eV +/20eV) negative secondary ions were extracted and detected by an electron multiplier.

SIMS results: negative ions

A subset of the analysed species is presented below. The complete data set is available for Excel:

SIMS Results Positive Ions (715 KB / XLS)

High mass resolution scans over mass 32

In order to determine the relative abundance of Sulphur in the resins a high mass resolution scan was performed using a Cameca ims-1270 at the University of Edinburgh using a 5nA, Cs+ primary beam with a net impact energy of 20KeV. Low energy (40eV window) negative secondary ions were extracted and detected by an electron multiplier. The mass resolution was ~4000.

Mass Scan 32 (210.93 KB / PDF)

Discussion

The Konductomet, Probemet, Varain Torr Seal and the domestic Araldite all contain high and variable quantities of elements that could compromise the accuracy of a SIMS analysis and should therefore be avoided.
Petropoxy contains high F and B together with Na and certainly should be avoided if studying B isotopes.
Varian Torr Seal also contains high F and variable amounts of S.
Domestic rapid set Araldite contains an unacceptable level of S.
High Mass Resolution scans confirm that Specifix has high S content while Petropoxy contains P as shown by the 31PH mass displayed and high F as shown by the 13C+19F peak.
Only Transoptic has a low Cl content, the majority of the other resins contain high Cl concentrations that could compromise the accuracy of a SIMS analysis.

Avg cps	1H	12C	16O	19F	31P	34S	35Cl
Araldite 1	103210.9	604142.4	278431.2	143.3	8.4	5018.1	24472.2
Araldite 2	97462.0	570725.2	279737.4	166.3	9.8	4682.9	24972.1
Ciba-Geigy 1	152547.1	577036.3	183923.0	26.1	0.0	2.4	44100.9
Ciba-Geigy 2	151389.8	575994.9	183455.1	20.6	0.1	2.0	43813.3
Epofix 1	161630.3	595732.2	182977.7	50.6	0.3	3.4	47323.3
Epofix 2	161114.4	601145.2	186002.8	51.5	0.5	2.3	47705.0
Epoheat 1	155836.1	562125.1	177080.4	40.9	0.0	1.9	6639.5
Epoheat 2	150379.4	546604.9	172108.5	12.3	0.3	2.8	6331.7
Epotek 1	165913.1	646453.1	206876.6	14.4	0.3	3.5	10445.8
Epotek 2	167596.9	630934.7	202268.4	20.4	0.1	6.8	10825.3
Epothin 1	161557.8	587276.6	181599.8	32.4	0.5	3.5	34409.7
Epothin 2	160408.6	582454.5	180029.7	25.6	0.4	3.3	34142.0
Epoxicure (65) 1	157012.4	576122.8	182511.5	34.4	0.0	2.4	29574.3
Epoxicure (65) 2	154937.4	568578.2	179551.5	36.1	0.0	2.0	29439.9
Epoxicure (RT) 1	157278.1	583654.5	185593.4	33.6	0.1	2.5	28972.0
Epoxicure (RT) 2	154156.6	572434.0	183487.0	34.0	0.0	2.1	28857.7
Konductomet 1	10171.9	163485.6	178398.7	253.3	4.4	22.5	768.5
Konductomet 2	4743.8	141963.3	160235.0	208.1	15.8	38.6	753.0
Korapox 1	140811.5	518964.3	161783.3	10.8	1.4	6.9	41518.1
Korapox 2	128456.8	462115.3	142529.1	9.0	1.1	5.9	37258.4
Petropoxy 1	161916.1	590259.9	198452.0	229900.7	40.4	0.6	4490.5
Petropoxy 2	164242.5	590249.7	199616.4	231140.6	40.1	0.3	4437.8
Probemet 1	42260.4	348691.5	3864146.3	77.3	8.9	29.1	4912.4
Robnor 1	39980.3	171837.7	53335.3	13.1	0.0	1.1	12257.9
Robnor 2	41091.7	174377.7	53995.6	13.0	0.1	2.0	12451.6
Specifix 1	150713.4	606233.2	204969.0	36.5	1.1	60.1	76316.9
Specifix 2	150336.5	609250.7	205630.9	35.3	1.3	56.8	76274.7
Transoptic 1	44923.6	340304.6	89027.6	8.8	0.0	0.6	52.5
Transoptic 2	43148.9	326341.4	85378.4	6.1	0.3	0.0	42.4
Varian 1	88726.9	537679.1	3873067.6	44173.8	77.4	1561.9	14268.6
Varian 2	15984.1	125548.3	865925.6	11518.3	13.0	381.4	2846.4

The imaging of mineral grains mounted in epoxy resin often results in the grains being surrounded by a damaged area of resin.

This is especially true if the sample has been subjected to high e-beam currents used for X-ray mapping, CL and BSE imaging. The resulting isolated grain can be unsuitable for further analytical measurements, and so the resilience of the resin to e-beam impact can be an important parameter in determining the resin to use.

An example of e-beam damage to epoxy resin

Sample preparation

Samples of 13 resins were mounted in individual 25mm diameter, 5mm deep, Al-rings. The three Beuhler hot press resins; TransOptic, ProbeMet and KonductoMet were mounted without the Al-rings.

The mounts were then ground using Beuhler UltraPrep nickel bonded diamond 74 micron and 20 micron discs followed by 1200 and 2500 silicon carbide paper. They were polished with 3 micron diamond for 15 minutes and then with 0.3 micron Al-oxide for 10 minutes, washed and then ultrasonically cleaned with 10% Decon 90. The samples were finally cleaned with ethanol before carbon coating using a Deton coater to produce a thin conducting film across the sample surface.

Measurement Procedure

The epoxy resins were carbon-coated before being loaded into the Scanning Electron Microscope. The electron beam was adjusted to have a current of 5nA, 20Kv and scanned an area at 5000x magnification for 10 minutes. The size and depth of the resulting raster pits were measured using the Tencor alpha-step 200 profilometer.

KonductoMet and ProbeMet were both too heterogeneous to produce a distinct raster pit, while TransOptic blistered under the beam showing a positive profile in comparison to the pits produced in the other samples.

Epoxy Resin	Shore Hardness	Sputter Depth (micons)
Robnor Resin	81.4 +/- 0.63	0.9
Petropoxy	85.3 +/- 0.78	1.4
Epoheat	80.1 +/- 0.5	0.8
Korapox	79.4 +/- 0.84	0.9
EpoxiCure (Room Temperature)	85.3 +/- 0.46	0.7
Specifix	82.8 +/- 0.45	0.8
Epothin	79.1 +/- 0.71	1.1
Epoifx	80.1 +/- 0.8	0.8
Ciba Geigy	82.1 +/- 1.23	0.7
Epoxicure (65'C)	84.9 +/- 0.18	0.9

The hardness of the resins were measured using a Shore S1-D hardness tester, factory calibrated and checked against the supplied reference block.

Ten readings were taken from each resin disk. The highest and lowest readings were rejected and the average and standard deviation of the remaining eight are listed here. The hardness of ProbeMet and KonductoMet was not tested because of the inhomogeneity of the material.

Notes on Hardness

There are many scales used in the measurement of hardness. The unit most frequently used for resins is the Shore D scale. Some values from everyday objects (apart from Indium) are listed below:

Perspex

87.84 +/- 0.12

PVC

81.10 +/- 0.47

Indium

29.5 +/- 0.42

Yellow BIC Biro Case

81.5 +/- 0.25

Epoxy Resin	Supplier Specification (If Known)	Shore D Hardness Avg (+/- Stdev)
EpoThin	78	79.1 +/- 0.71
EpoHeat	85	80.1 +/- 0.50
EpoxiCure (Room Temperature Cure)	82	85.3 +/- 0.46
EpoxiCure (Cured at 65'C)	82	84.9 +/- 0.18
TransOptic	-	82.4 +/- 0.53
SpeciFix-20	84	82.8 +/- 0.45
EpoFix	78	80.1 +/- 1.10
Ciba Geigy  MY778 & HY951	-	82.1 +/- 1.23
Robnor Resin PX771c	85	81.4 +/- 0.63
Korapox 439	-	79.4 +/- 0.84
Petropoxy	-	85.3 +/- 0.78
Domestic Rapid Set Araldite	-	78.9 +/- 0.34
Domestic Araldite	-	78.5 +/- 0.76
Varian Torr Seal	-	83.8 +/- 0.97
Epotek	85	87.5 +/- 0.14

Nanoindentation Tests

Experiments were carried out by Wenzhong Zhu at the University of the West of Scotland. Two sets of indentation test were carried out on each specimen: One test batch of three test points at maximum load of 100 mN, the other batch of nine test points at a maximum load of 10 mN. The spacing between the indentation points is 100 µm.

Indent Load ~10mN

Epoxy Resin	Youngs Modulus GPa Avg (+/- Stdev)	Hardness GPa Avg (+/- Stdev)
Korapox 439	2.335 +/- 0.050	0.084 +/- 0.001
Transoptic	2.737 +/- 0.056	0.094 +/- 0.002
EpoThin	3.495 +/- 0.098	0.126 +/- 0.007

Indent Load ~100mN

Epoxy Resin	Youngs Modulus GPa Avg (+/- Stdev)	Hardness GPa Avg (+/- Stdev)
Korapox 439	2.323 +/- 0.039	0.079 +/- 0.001
Transoptic	2.777 +/- 0.015	0.090 +/- 0.002
EpoThin	3.506 +/- 0.016	0.123 +/- 0.001

Test procedure and results for 2 hours, 24 hours and 3 months.

Cleaning Procedure

After cutting to a thickness of 5mm, the 25mm diameter disks were:

Washed
Ultrasonic Clean with 10% Decon 90
Rinsed with deionised water
Two Ultrasonic Cleans with deionised Water
Dried @50'C for ~2Hr

Test Procedure

Four examples of each resin (except Varian Torr Seal and the 'domestic' Araldites) were prepared immediately before pump testing following the manufacturers recommended cure time and the cleaning routine outlined above.

Four samples of each resin type were loaded into the vacuum test chamber and pumped by a rotary pump (Alcatel 2012) for 1 minute followed by the turbo-molecular pump (Pfeiffer TPH240). The vacuum recording started after a pump-down time of 5 minutes by which time the vacuum was around 1e-4Torr.

Four vacuum measurements were made:

Varian MultiGauge Thermocouple. The gauge output was only used to monitor the backing pressure and to confirm that the vacuum was suitable to start the turbo-molecular pump.
Varian MultiGauge Cold Cathode and/or Bayard-Alpert UHV gauge.
Thermo (VGQ), Residual Gas Analyser. The spectra were used to characterise the different resins.
Thermo (VGQ), total pressure measure. This vacuum measure was used to monitor the pump-down time.

Two hour test results

This pump test was performed 24hrs after the resin was mixed. The vacuum was recorded by the Thermo (VGQ) in total pressure mode and confirmed by the Varian Cold Cathode gauge and presented as the final vacuum reading.

We have provided a comparison of all of the pump tests via a downloadable PDF document.

Pump Down Rotated (46.03 KB / PDF)

Resin	Final Vacuum (2Hr)	Pump Graph (PDF document)
None	2.8e-7 Torr	Document tp blank 2 hours (8.95 KB / PDF)
EpoThin	8.4e-7 Torr	Document tp epothin 2 (8.8 KB / PDF)
TransOptic	1.4e-5 Torr	Document tp transoptic 2 (10.67 KB / PDF)
KonductoMet 1	4.8e-6 Torr	Document tp konduct 2 (10.03 KB / PDF)
Korapox 439	5.4e-6 Torr	Document tp korapox 2 (10.34 KB / PDF)
Epofix	3.2e-6 Torr	Document tp epofix (13.38 KB / PDF)
Specifix 20	5.1e-6 Torr	Document tp specfix 2 (10.97 KB / PDF)
Ciba Geigy	2.5e-6 Torr	Document ciba pump 2 (10.36 KB / PDF)
ProbeMet	5.4e-7 Torr	Document tp probemet 2 (8.78 KB / PDF)
Robnor Resin	3.3e-6 Torr	Document tp robnor 2 (8.94 KB / PDF)
Epoxicure (Room Temperature)	3.4e-6 Torr	Document pump epoxicure rt (10.75 KB / PDF)
Epoxicure (cured at 65oC)	3.6e-6 Torr	Document epoxicure 65 (10.83 KB / PDF)
Petropoxy	3.7e-6 Torr	Document tp petropoxy 2 (8.87 KB / PDF)
EpoHeat	4.2e-6 Torr	Document tp epoheat 2 (10.2 KB / PDF)

24 hour test results

The 24Hr pump test was performed ~30 days after the resin was prepared and is believed to give a good indication of the resins suitability for the practical preparation of material for SIMS analysis. Throughout the testing period the empty vacuum chambers residual gases and ultimate (24hr) vacuum were routinely monitored to check how these parameters varied over time. The results show a slight but steady improvement in the ultimate chamber vacuum over the 30 day test period.

We have provided a comparison of all of the pump tests via a downloadable PDF document.

Pump Down Rotated (421.68 KB / PDF)

Resin	Final Vacuum (24Hr)	Pump Graph (PDF document)
None	7.12e-8 Torr	Document uhv24blank (68.83 KB / PDF)
EpoThin	1.64e-7 Torr	Document uhv24ethin (23.94 KB / PDF)
TransOptic	3.10e-7 Torr	Document uhv 24 topt (42.45 KB / PDF)
KonductoMet 1	2.40e-7 Torr	Document uhv24kmet (37.54 KB / PDF)
Korapox 439	1.10e-7 Torr	Document uhv24kpox (41.12 KB / PDF)
Epofix	1.60e-7 Torr	Document uhv24efx (71.54 KB / PDF)
Specifix 20	2.10e-7 Torr	Document uhv 24 sfx (43.7 KB / PDF)
Ciba Geigy	1.90e-7 Torr	Document uhv24cg (36.68 KB / PDF)
ProbeMet	1.60e-7 Torr	Document uhv 24 pmet (23.93 KB / PDF)
Robnor Resin	1.11e-7 Torr	Document uhv 24 rr (26.44 KB / PDF)
Epoxicure (Room Temperature)	1.70e-7 Torr	Document uhv24ecurert (40.9 KB / PDF)
Epoxicure (cured at 65oC)	1.60e-7 Torr	Document uhv 24 ecure65 (44.24 KB / PDF)
Petropoxy	1.20e-7 Torr	Document uhv 24 pxy (25.41 KB / PDF)
EpoHeat	1.40e-7 Torr	Document uhv24eheat (36.7 KB / PDF)

Three month cure test results

A final 2Hr pump test was performed ~3 months after the resin was prepared. The samples were kept in a desiccator and the test chamber continually pumped over this ~3 month time period and the base vacuum improved. The results show a significant improvement in the ultimate chamber vacuum after 3 months hardening.

A comparison of all of the pump tests is provided via a downloadable PDF document.

3 month Pump (305.09 KB / PDF)

Resin	Final Vacuum (2Hr)
None	2.8e-8 Torr
EpoThin	5.3e-8 Torr
TransOptic	1.5e-7 Torr
KonductoMet 1	9.8e-8 Torr
Korapox 439	7.1e-8 Torr
Epofix	7.4-8 Torr
Specifix 20	8.5e-8 Torr
Ciba Geigy	5.8e-8 Torr
ProbeMet	5.9e-8 Torr
Robnor Resin	6.6e-8 Torr
Epoxicure (Room Temperature)	6.9e-8 Torr
Epoxicure (cured at 65oC)	5.9e-8 Torr
Petropoxy	9.3e-8 Torr
EpoHeat	6.6e-8 Torr

Residual Gas Analysis

The residual gases within the vacuum chamber were routinely monitored during the pump tests. These gases, although not all identified, can provide a distinctive 'fingerprint' of the resins.

Discussion of Results

Comparison of the final vacuum achieved for each resin under the three test conditions is illustrated in our downloadable PDF document.

3 test comparison (18.32 KB / PDF)

The relative vacuum achieved has been calculated from the final vacuum recorded minus the base vacuum of the chamber. It demonstrates that after ~3 months the same vacuum maybe achieved that previously took 24hrs.

Epothin and ProbMet both performed well under all 3 test conditions.

Results summary

Ideally, the resins should have a low viscosity, set quickly, set hard, be compatible at high vacuum and contain no element that will compromise the SIMS chemical or isotopic analysis. In addition, it should be suitable for petrological study, imaging (e.g. cathodoluminescence (CL), backscatter electron (BSE)) and electron micro-probe analysis (EPMA). No resin meets all these requirements.

Viscosity	5 Stars for the viscosity closest to water	Image
Hardness	5 Stars for the resin closest to the hardness of common rock forming minerals	Image
Cure time	5 Stars for shortest cure time	Image
Composition	5 Stars for the cleanest composition that would not compromise a SIMS analysis	Image
Cathodoluminescence	5 Stars for the lowest luminescence	Image
e-beam damage	5 Stars for the most robust resin to e-beam bombardment	Image
Bonding, gap and relief	5 Stars for the best bonding, smallest gap and minimal polishing induced relief	Image

The table below presents a star rating, culminating in an Engwell score. Clearly, some materials or analyses may put a different importance on any of the properties.


Epoxy Resin	Viscosity	Vacuum Test	Hardness	Cure Time	Composition	Bonding	Gap	Relief	'Luminescence	e-beam Damage	Engwell Score
EpoThin	Image	Image	Image	Image	Image	Image	Image	Image	Image	Image	32
EpoHeat	Image	Image	Image	Image	Image	Image	Image	Image	Image	Image	34
EpoxiCure (Cured at Room Temperature)	Image	Image	Image	Image	Image	Image	Image	Image	Image	Image	40
EpoxiCure (Cured at 65oC)	Image	Image	Image	Image	Image	Image	Image	Image	Image	Image	33
TransOptic	Image	Image	Image	Image	Image	Image	Image	Image	Not Tested	Image
ProbeMet	Image	Image	Not Tested	Image	Image	Image	Image	Image	Not Tested	Not Tested
KonductoMet	Image	Image	Not Tested	Image	Image	Image	Image	Image	Not Tested	Not Tested
SpeciFix-20	Image	Image	Image	Image	Image	Image	Image	Image	Image	Image	36.5
EpoFix	Image	Image	Image	Image	Image	Image	Image	Image	Image	Image	36
Ciba Geigy MY778 & HY951		Image	Image	Image	Image			Image	Image		38
Robnor Resins PX771c		Image	Image	Image	Image			Image	Image	Image	28
Korapox 439	Image		Image	Image			Image	Image	Image	Image	24.5
Domestic Rapid Set Araldite	Image	Not Tested	Image		Image	Not Tested	Not Tested	Not Tested	Not Tested	Not Tested
Domestic Araldite	Image	Not Tested	Image	Image	Image	Not Tested	Not Tested	Not Tested	Not Tested	Not Tested
Varian Torr Seal	Image	Not Tested	Not Tested	Image	Image	Not Tested	Not Tested	Not Tested	Not Tested	Not Tested
Petropoxy	Image	Image			Image	Image				Image	29

Comments

The facility recommends the use of EpoxiCure, SpeciFix-20 or EpoFix for SIMS analysis, although other resins should be considered for specific requirements such as low viscosity.
Transoptic shatters samples during the pressure/heating procedure and we wonder why it is suggested for delicate samples. It produces a network of gaps in contact with the sample and the surfaces of the pressure vessel. Its pump-down time is long and blisters badly under electron beam impact.
Konductomet also fractures samples during the pressure/heating procedure.
Rapid-set araldite has a high viscosity and contains C, O, Al and Cl as well as sulphur.

This article was published on 2026-02-18

Suppliers

Epoxy Resins Tested

Suppliers information

Notes on viscosity:

Notes on hardness:

Suppliers information

Links to suppliers websites

Resin preparation recipes | sample resin preparation procedures

Testing and results

Bonding

Sample Preparation

Bonding

Polishing Relief

Cathodoluminescence

Sample preparation

Analytical Procedure

Results

Epoxy Resin

Average Grey Value (0-255)

Cathodoluminescence Image

Compositions

X-Ray analysis: sample preparation

X-Ray analytical conditions

X-ray results

SIMS analysis: sample preparation

SIMS analytical procedure: positive ions

SIMS results: positive ions

SIMS analytical procedure: negative ions

SIMS results: negative ions

High mass resolution scans over mass 32

Discussion

E-beam damage

Sample preparation

Measurement Procedure

Hardness tests

Notes on Hardness

Nanoindentation Tests

Vacuum pump test

Cleaning Procedure

Test Procedure

Two hour test results

24 hour test results

Three month cure test results

Residual Gas Analysis

Discussion of Results

Results summary

Comments