Weights of Materials

The below table supplies the basic weights of many patternmaking materials and the multipliers (factors) used to convert the weight of a simple solid pattern (no cores of core prints) to the weight of its casting. The variation in the weight of alloys together with the wide range of moisture contents and compositions of woods accounts for the discrepancy of values listed in several sources which were averaged to compile this table. Furthermore, no correction has been made to compensate for the use of finishing materials or for the shrink rule. The numbers are limited to three digits because a close approximation is all that can be expected.

The first vertical column tabulates the pattern materials--wood synthetic and metals. The second column lists the weight of a cubic inch and the third column the weight of a cubic foot of the material. The fourth column lists the specific gravity (SG) of each material. The polyester putties and epoxies are not listed because their weights varies widely depending on the filler; the manufacturer's SG is generally not available and any material having the same SG will provide the rest of the data. Methods of calculation working with only the SG of a material closes these notes.

The multiplier will appear at the intersection of the pattern's material (horizontal line) and the metal (vertical column) which is to be cast.

Example--white pine pattern and cast-iron has a multiplier of 16.

Multiply the weight of a simple solid pattern by this multiplier to find the weight of the casting. The weight of a solid white pine pattern (no cores of core prints) when multiplied by 16 equals the weight of its iron casting.

Example--A solid simple pine pattern of 6.5 lbs. x 16 = 104 lbs.

Additional conversions multipliers can be derived by finding the ratio of the weight of equal quantities of the two materials:

		1 cu. ft. of metal to be cast
		-----------------------------
		1 cu. ft. of pattern material	= multiplier
	
		1 cu. ft. of cast iron		450
	Example: ------------------------ =  	--- = 16.0
		1 cu. ft. of white pine	 	28

Specific gravity (SG) is the ratio of the weight of any material to the weight of an equal volumn of distilled water at 4C (39F), water's most concentrated temperature, often stated as weight in air divided by weight immersed in water. SG is unit, equally applicable to English and metric systems. A column of SG's is included because this is often the only basic unit available; a ratio of SG's produces identical multipliers:

		1 cu. ft. of cast iron		7.20
	Example: ------------------------ =  	--- = 16.0
		1 cu. ft. of white pine	 	0.45

Table of Weights

Pattern Material	lb/in(3)	lb/ft(3)	SG	Aluminum	Brass	Bronze	Iron,gray or malleable	Lead	Magnesium	Steel
Wood
Apple	.027	46	0.74	3.65	11.4	11.9	9.8	15.4	2.37	10.6
Ash,American	.022	38	0.61	4.42	13.8	14.5	11.8	18.7	2.86	12.8
Balsa	.0035	6	.096	28.0	87.3	91.7	75.0	118	18.2	81.0
	.0087	15	0.24	11.2	34.9	36.6	30.0	47	7.26	32.5
Beech, compreq	.027	47	0.75	3.57	11.2	11.7	9.6	15.1	2.32	10.4
Beech, solid	.023	40	0.64	4.20	13.1	13.8	11.3	17.8	2.72	12.2
Beech, staypak	.050	87	1.39	1.93	6.0	6.3	5.2	8.2	1.25	5.6
Birch	.025	44	0.71	3.81	11.9	12.5	10.2	16.2	2.47	11.1
Cedar,white	.012	20	0.32	8.40	26.2	27.5	22.5	36.6	5.45	24.4
Cedar, red	.019	33	0.53	5.09	15.8	16.6	13.6	21.5	3.33	14.7
Cherry, black	.020	34	0.54	4.94	15.4	16.2	13.2	20.9	3.21	14.3
Chestnut	.023	39	0.63	4.30	13.4	14.1	11.5	18.2	2.79	12.5
Cork	.0087	15	0.24	11.2	34.9	36.7	30.0	47.4	7.26	32.5
Cypress	0.16	28	0.45	5.0	18.7	19.5	16.1	25.4	3.89	17.4
Ebony	.045	77	1.23	2.18	6.8	7.14	5.8	9.2	1.41	6.3
Elm,American	0.24	41	0.66	4.09	12.8	13.4	10.9	17.3	2.65	11.9
Fir, Douglas	.016	28	0.45	6.00	18.7	19.5	16.0	25.4	3.89	17.4
Fir, plywood	0.20	34	0.54	4.94	15.4	16.2	13.2	20.9	3.21	14.3
Gum, black	.020	35	0.56	4.80	15.0	15.7	12.8	20.3	3.11	13.9
Hickory	.030	52	0.83	3.23	10.0	10.6	8.7	13.7	2.09	9.4
Lignum-vitae	.050	87	1.39	1.93	6.0	6.3	5.2	8.2	1.25	5.6
Mahogany, hard	.031	53	0.85	3.17	9.9	10.4	8.5	13.4	2.05	9.2
Mahogany,soft	.020	35	0.56	4.80	15.0	15.7	12.8	20.3	3.11	13.9
Maple, sugar	.025	44	0.71	3.81	11.9	12.5	10.2	16.2	2.47	11.1
Oak, red	.024	41	0.66	4.09	12.8	13.4	10.9	17.3	2.65	11.9
Oak, white	.028	48	0.77	3.50	10.9	11.5	9.4	14.8	2.27	10.1
Orange, osage	.029	50	0.81	3.36	10.5	11.0	9.0	14.2	2.18	9.7
Pine, white	.016	28	0.45	6.00	18.7	19.5	16.1	25.4	3.89	17.4
Pine, yellow	.024	42	0.67	4.00	12.5	13.0	10.7	16.9	2.59	11.6
Popular, yellow	.018	31	0.50	5.41	16.9	17.7	14.5	22.9	3.51	15.7
Redwood	.014	24	0.38	7.00	21.8	22.9	18.7	29.6	4.54	20.3
Spruce	.016	27	0.43	6.22	19.4	20.4	16.7	26.3	4.04	18.0
Walnut, black	.021	37	0.59	4.54	14.2	14.9	12.2	19.2	2.96	13.1
Teak	.021	37	0.59	4.54	14.2	14.9	12.2	19.2	2.96	13.1

Synthetic
Plaster of paris	.090	154	2.47	1.09	3.04	3.57	2.92	4.62	.707	3.16
Polystryrene foam	---	1.0	.016	168	524	550	450	711	109	487
	---	1.5	.024	112	350	367	300	474	72.6	325

Metals
Aluminum	.097	168	2.70	1.0	3.12	3.27	2.68	4.23	0.65	2.90
Brass, yellow	.300	524	8.40	.321	1.0	1.105	.858	1.36	0.21	.929
Bronze	.318	550	8.80	.305	.953	1.0	.818	1.29	0.20	.885
Copper	.318	550	8.80	.305	.953	1.0	.818	1.29	0.20	.885
Gold	.697	1204	19.3	.140	.435	.457	.374	0.59	0.09	.404
Iron, cast gray	.260	450	7.20	.373	1.16	1.22	1.0	1.58	0.24	1.08
Iron, malleable	.264	456	7.30	.368	1.15	1.21	.986	1.56	.239	1.07
Lead	.410	711	11.4	.236	.737	.774	.632	1.0	.153	.684
Magnesium	.063	109	1.75	1.54	4.81	5.05	4.12	6.52	1.0	4.47
Silver	.380	655	10.5	.256	.800	.839	.687	1.09	.166	.743
Steel	.282	.487	7.8	.345	1.08	11.3	.924	1.46	.224	1.0
Pattern Material	lb/in(3)	lb/ft(3)	SG	Aluminum	Brass	Bronze	Iron,gray or malleable	Lead	Magnesium	Steel

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