PT4925 Aluminum Filled High Temperature Epoxy Casting Resin


PT4925 is an aluminum filled high temperature epoxy resin for use in making cast tools and parts requiring heat resistance and good thermal conductivity. PT4925 has a high aluminum content which insures these properties and allows easy machining of the finished castings. It handles easily, filling mold cavities well, and it reproduces fine details in the pattern surface with ease. Service temperature in the 400 o F range is routine with PT4925 and, with the proper hardener selection, it will perform very well in cyclic 500 o F temperature applications. PT4925 does not contain vinyl cyclohexane diepoxide (VCHD) or other regulated ingredients. Typical uses for PT4925 include foundry patterns, vacuum form molds, matched dies, compression mold dies, autoclave fixtures and spacers and other applications where good stability and thermal conductivity are required.

Three hardeners are listed here for use with PT4925. They provide a range of working times for castings of various thickness. These hardeners are low in viscosity, so they aid in thinning the mixture for best detail reproduction. These hardeners give exceptional high temperature properties, and they are low potential toxicity products. They do not contain methylene dianiline (MDA), or other aniline derivatives. They are non-staining materials, and will not crystallize in normal shipping and storage conditions.

– PT4925-B: Shorter Pot life hardener with good gel at room temperature. For smaller castings with good heat resistance after a post cure. Gel time: 40-50 min.
– PT4925-B1: Longer working time than PT4925-B, for larger castings. Gel time: 3-4 hours.
– PT4925-B2: Very long pot life hardener for large mass castings. Must be heat cured on the pattern. Low viscosity thins the resin well for better pouring characteristics. Gel time: 8-12 hours.

 PT4925-APT4925-BPT4925-B1PT4925-B2ASTM Method 
497000 cps
1700 cps
150 cps
200 cps
Specific Gravity, gms./cc
Mix Ratio, by Weight

100 : 8
100 : 10
100 : 10
Pot Life, 4 fl oz Mass @ 77°F
40 – 50 min.
3 – 4 hours
8 – 12 hours

* PT4925 resin is a high viscosity liquid at room temperature. Some users prefer to warm the resin to lower the viscosity for easier pouring. This is especially useful where highly detailed castings, or difficult filling problems are involved. Since heating shortens the pot life, it is recommended that PT4925 Part B2 hardener be used to give longer working time for pouring.


PT4925 has a high aluminum filler content which may settle in long-term storage. Stir the resin before each use to redisperse any filler that may have settled. Castings made with Part B and Part B1 hardeners will gel at room temperature, and, after a good hard gel, the castings can be demolded for the final heat curing cycle. Care should be taken if the castings are to be demolded before post curing,
as high temperatures service hardeners typically give somewhat brittle cures at room temperature only. This is not as much a concern with the Part B hardener, but a definite consideration with the Part B1 hardener. The Part B2 is a very slow curing hardener, and castings made with it should be cured entirely on the master pattern. Castings made with PT4925 Part B should be allowed to cure at room temperature on the pattern for a minimum of 18 hours before post curing. Part B1 hardener will require a 24 hour minimum room temperature cure on the pattern before post curing. Hardener PT4925 Part B2 will require longer than 24 hours before post curing, the exact time being determined by the size of the casting and the amount of any bulk filler content. An oven post cure is recommended for all castings for the maximum stability in service. A typical cure cycle would be: Gel for the required time at room temperature, plus 3 to 4 hours at 150 o F, 250 o F and 350 o F. This schedule represents the minimum recommended cure schedule. Longer time at room temperature followed by longer times at smaller incremental increases will usually result in lower shrinkage and less stress buildup in the finished castings.


Gallon Kit
Pail Kit
PT4925 Part A
14 lb.
55 lb.
PT4925 Part B
1.15 lb.
4.5 lb.
PT4925 Part B1
1.4 lb.
5.5 lb.
PT4925 Part B2
1.4 lb.
5.5 lb.

Inasmuch as PTM&W Industries, Inc. has no control over the use to which others may put material, it does not guarantee that the same results as those described herein will be obtained. The above data was obtained under laboratory conditions, and to the best of our knowledge is accurate. This information is presented in good faith to assist the user in determining whether our products are suitable for his application. No warranty or representation, however is intended or made, nor is protection from any law or patent to be inferred, and all patent rights are reserved. Before using, user shall determine the suitability of the product for his intended use, and user assumes all risk and liability whatsoever in connection therewith. In no event with PTM&W Industries, Inc. be liable for incidental or consequential damages. Buyer’s sole and exclusive remedy in such instances shall be limited to replacement of the purchase price.

 PT4925 A/B
PT4925 A/B1
PT4925 A/B2
ASTM Method
Mixed Viscosity, @77°F, centipoise
178,000 cps
54000 cps
74000 cps
Pot Life, 4 fl. oz. Mass @ 77°F
40 – 50 min.
3 – 4 hr.
8 – 12 hr.
Cured Hardness, Shore D
91 Shore D
91 Shore D
91 Shore D
Shrinkage, in/in
(Mold #1,
 .53 gal)
(Mold #3,
1.23 Gal)
(Mold #3,
1.23 Gal)
Specific Gravity, grams, cc
Density, lb./cu. in.
Specific Volume,  cu. in./lb.
Tensile Strength, psi 
8100 psi
8380 psi
9700 psi
Elongation at Break, %
1.32 %
1.32 %
1.86 %
Compressive Strength, psi
20760 psi
21120 psi
21840 psi
Glass Transistion Temperature, DMA:
309°F365°F350°F D4065


PTM&W epoxy products are made from raw materials carefully chosen to minimize or even eliminate toxic chemicals, and therefore offer the user high performance products with minimum hazard potential when properly used.  Generally, the PTM&W epoxy resins and hardeners will present no handling problems if users exercise care to protect the skin and eyes, and if good ventilation is provided in the work areas.  However, all epoxy resins and hardeners can be irritating to the skin, and prolonged contact may result in sensitization; and breathing of mist or vapors may cause allergenic respiratory reactions, especially in highly sensitive individuals.  As such, avoid contact with eyes and skin, and avoid breathing vapors.  Wear protective rubber apron, clothing, gloves, face shield or other items are required to prevent contact with the skin.  In case of skin contact, immediately wash with soap and water, followed by a rinse of the area with vinegar, and then a further wash with soap and water.  The vinegar will neutralize the hardener and lessen the chances of long term effects.  Use goggles, a face shield, safety glasses or other items as required to prevent contact with the eyes.  If material gets into the eyes, immediately flush with water for at least 15 minutes and call a physician.  Generally, keep the work area as uncluttered and clean as possible, and clean up any minor spills immediately to prevent accidental skin contact at a later time.  Keep tools clean and properly stored.  Dispose of trash and empty containers properly.  Do not use any of these types of products until Material Safety Data Sheets have been read and understood.