ASTM D7029-17

Standard Test Method for Determination of Reactivity of Unsaturated Polyesters and Vinyl Esters at 180.0°F (82.2°C)

SIGNIFICANCE AND USE
5.1 This test method is used to measure the reactivity of different lots of unsaturated polyester and vinyl ester resins. The information provided by this test is often used for assessing the predicted performance of a resin when used in elevated temperature as part of the process used to convert the resin into a finished product.  
5.2 The method is used in research and development by companies that manufacture resins and for incoming quality control companies using these polymers as raw materials for production. The method is based on the methods which were previously outlined in the Handbook of Reinforced Plastics, “Procedure for Running Exotherm Curves Using the Block Test Method” published by the Society of the Plastics Industry.
SCOPE
1.1 This standard provides a standardized test method for determining the gelation and exotherm curve of unsaturated polyester and vinyl ester resins. This method provides guidance for measurement of the “Standard 180°F (82.2°C) Exotherm Curve” along with information on potential variances of the measurement for some special resins. This test method provides information concerning the reactivity of unsaturated polyester and vinyl ester resins as they go through polymerization after mixing with the initiator.
Note 1: There is no known ISO equivalent to this standard, although ISO 584 is similar.  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems has the potential to result in nonconformance with the standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Jul-2017
• ICS: 71.080.70 - Esters
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.18 - Reinforced Thermosetting Plastics

Relations

• Replaces: ASTM D7029-09 - Standard Test Method for Determination of Reactivity of Unsaturated Polyesters and Vinyl Esters at 180.0F [82.2°C]
• Effective Date: 15-Jul-2017
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM D883-12e1 - Standard Terminology Relating to Plastics
• Effective Date: 15-Nov-2012
• Refers: ASTM D883-11 - Standard Terminology Relating to Plastics
• Effective Date: 15-May-2011
• Refers: ASTM D883-08 - Standard Terminology Relating to Plastics
• Effective Date: 01-Mar-2008
• Refers: ASTM D883-07 - Standard Terminology Relating to Plastics
• Effective Date: 01-May-2007
• Refers: ASTM D883-00 - Standard Terminology Relating to Plastics
• Effective Date: 10-Aug-2000

Overview

ASTM D7029-17 is the internationally recognized standard test method for determining the reactivity of unsaturated polyester and vinyl ester resins at 180.0°F (82.2°C). Developed by ASTM International, this test method provides a standardized procedure for measuring the gelation and exotherm curve of these resins as they undergo polymerization, typically after mixing with the initiator. Assessing resin reactivity is crucial for predicting performance during elevated temperature processing and for ensuring quality and consistency in both research and manufacturing applications.

Key Topics

• Reactivity Measurement: The standard specifies how to measure the gel time, cure time, interval time, and peak exotherm temperature of unsaturated polyester and vinyl ester resins.
• Standardized Conditions: Testing is conducted at a controlled temperature of 180.0°F (82.2°C) using defined apparatus such as calibrated thermocouples, pyrometers, and temperature-controlled baths.
• Initiators: Benzoyl peroxide is commonly used, though other initiator systems may be acceptable when mutually agreed upon.
• Data Analysis: The method provides guidelines for interpreting exotherm curves and reporting key data, such as gel and cure times, to characterize resin performance.
• Precision and Repeatability: Results depend on various factors including resin type, initiator, and bath control. The method emphasizes proper calibration and detailed reporting to ensure reproducible results.

Applications

ASTM D7029-17 delivers practical value across a range of industries and laboratory settings:

• Resin Manufacturing & R&D: Resin producers utilize this standard to compare the reactivity of different lots, assess batch-to-batch consistency, and conduct product development work on new unsaturated polyester and vinyl ester formulations.
• Incoming Material Quality Control: Manufacturers using these polymers as raw materials test incoming lots for compliance and suitability in downstream production processes such as pultrusion, casting, and molding.
• Product Performance Prediction: Information obtained from this test method is used to anticipate how a resin will behave at elevated temperatures during manufacturing, helping optimize process parameters and improve finished product quality.
• Comparative Testing: The standard enables suppliers and customers to speak a common language when specifying reactivity requirements and verifying the performance of supplied materials.

Related Standards

• ASTM D883: Standard terminology relating to plastics, providing definitions used within D7029-17.
• Handbook of Reinforced Plastics Procedures: Reference procedure for running exotherm curves using the block test method, which forms the basis of ASTM D7029-17.
• ISO 584: Though not identical, this ISO standard covers reactivity determination of reinforced plastics based on unsaturated polyester resins at 80°C.

Practical Benefits

Implementing ASTM D7029-17 allows organizations to:

• Ensure repeatable, reliable measurement of resin reactivity
• Maintain strict quality control procedures for incoming materials and in-process products
• Reduce production variability and optimize end-use performance of composite and molded products
• Facilitate technical communication across suppliers, researchers, and manufacturers

Keywords

ASTM D7029, unsaturated polyester resin, vinyl ester resin, resin reactivity, exotherm curve, gel time, cure time, peak exotherm, thermoset polymers, quality control, R&D, elevated temperature polymerization, benzoyl peroxide initiator, standard test method, plastics testing, composite manufacturing

By following ASTM D7029-17, industry professionals can standardize their approach, meet regulatory and customer requirements, and reliably advance the science of thermoset polymer development and application.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7029 − 17
Standard Test Method for
Determination of Reactivity of Unsaturated Polyesters and
Vinyl Esters at 180.0°F (82.2°C)
This standard is issued under the fixed designation D7029; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2.2 Society of Plastics Industry, Inc.:
Handbook of Reinforced Plastics “Procedure for Running
1.1 This standard provides a standardized test method for
Exotherm Curves Using the Block Test Method”
determining the gelation and exotherm curve of unsaturated
2.3 ISO Standard:
polyester and vinyl ester resins. This method provides guid-
ISO584 ReinforcedPlasticsBasedonUnsaturatedPolyester
ance for measurement of the “Standard 180°F (82.2°C) Exo-
Resins—Determination of Reactivity at 80°C
therm Curve” along with information on potential variances of
the measurement for some special resins. This test method
3. Terminology
provides information concerning the reactivity of unsaturated
polyester and vinyl ester resins as they go through polymer-
3.1 Definitions—For definitions of terms that appear in this
ization after mixing with the initiator.
practice relating to plastics, refer to Terminology D883.
NOTE 1—There is no known ISO equivalent to this standard, although
3.2 Definitions of Terms Specific to This Standard:
ISO 584 is similar.
3.2.1 gel time—the period of time in minutes and seconds
1.2 The values stated in either SI units or inch-pound units
required for the recording pyrometer to go from a temperature
are to be regarded separately as standard. The values stated in
below (usually 10 to 30°F or 5.5 to 16°C) bath temperature to
each system are not necessarily equivalents; therefore, each
10°F (5.55°C) above the bath temperature, typically 150°F
system shall be used independently of the other. Combining
(65.5°C) to 190°F (78.8°C) for a bath at 180°F (82.2°C).
values from the two systems has the potential to result in
3.2.2 cure time—the period of time in minutes and seconds
nonconformance with the standard.
required for the recording pyrometer to go from a temperature
1.3 This standard does not purport to address all of the
below (usually 10 to 30°F or 5.5 to 16°C) bath temperature to
safety concerns, if any, associated with its use. It is the
the maximum temperature reading, typically 150°F (65.5°C) to
responsibility of the user of this standard to establish appro-
the maximum temperature for a bath at 180°F (82.2°C).
priate safety and health practices and determine the applica-
3.2.3 interval time—the period of time in minutes and
bility of regulatory limitations prior to use.
seconds required for the recording pyrometer to go from 10°F
1.4 This international standard was developed in accor-
(5.5°C) above the bath temperature to the maximum tempera-
dance with internationally recognized principles on standard-
ture reading, typically 190°F (78.8°C) to the maximum tem-
ization established in the Decision on Principles for the
perature. Thus, interval time is cure time minus gel time.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical 3.2.4 peak exotherm—the maximum temperature reached
Barriers to Trade (TBT) Committee. during the testing.
3.2.5 recording pyrometer—a broad class of temperature
2. Referenced Documents
measuringdevicesincludingthermocoupleswiththeabilityfor
2.1 ASTM Standards:
continuous temperature recording.
D883 Terminology Relating to Plastics
3.2.6 initiator—a compound that generates free radicals to
start the free radical polymerization of the unsaturated polyes-
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
ter and vinyl ester resins.
and is the direct responsibility of Subcommittee D20.18 on Reinforced Thermoset-
3.2.6.1 Discussion—An initiator is typically a single
ting Plastics.
peroxide, but there are instances in which a combination of
Current edition approved July 15, 2017. Published August 2017. Originally
approved in 2004. Last previous edition approved in 2009 as D7029 - 09. DOI:
initiators is used.
10.1520/D7029-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7029 − 17
4. Summary of Test Method 6.2 It is possible that the control of the bath temperature and
the circulation within the bath will affect the results of the test.
4.1 Polyester or vinyl ester resin is mixed with the initia-
Care shall be taken to control the bath temperature and
tor(s) in a beaker causing a polymerization of the resin to
agitation to comply with the method instructions.
occur. Heat will accelerate the polymerization reaction. The
exotherm generated by the resin as it cures is measured using
7. Apparatus
a thermocouple. The curve is plotted and the time to reach
various temperatures along with the peak temperature obtained
7.1 Recording Pyrometer, Iron Constantan, 60 in. (1.5 m)
(peak exotherm) is determined. The initiator normally em-
per hour charts speed or equivalent.
ployedtogeneratethetestresultsisbenzoylperoxide,although
7.2 Thermometer, with divisions every 0.1°F (0.05°C) ca-
the method is valid with other initiator systems.
pable of reading a minimum of 180 6 1°F (82.2 6 0.5°C) or
4.2 Thetestmethodisusefulinprovidinginformationabout
equivalent.
the heat generated during cure of the resin and the length of
7.3 Constant Temperature Water Bath, or alternate media
time the resin remains in the liquid state prior to polymeriza-
bathcapableofbeingcontrolledto180 60.5°F(82.2 60.2°C)
tion into solid form.
with an agitation rate of 1 to 2 times the bath capacity per
minute.Thebathshallhaveaminimumcapacityof2.5gal(8.8
5. Significance and Use
L) an shall be fitted with a cover with access holes for the bath
5.1 This test method is used to measure the reactivity of
heater, thermometer, and test tubes in order to minimize
different lots of unsaturated polyester and vinyl ester resins.
evaporation of water.
The information provided by this test is often used for
7.4 Borosilicate Glass Test Tubes, of 19 mm diameter and
assessing the predicted performance of a resin when used in
150 mm length with plain end and lip.
elevated temperature as part of the process used to convert the
resin into a finished product.
7.5 “Type J” Thermocouple Needle, made from 304 stain-
less steel, 6 in. (152 mm) in length, with an outside diameter of
5.2 The method is used in research and development by
⁄8 in. (3.2 mm) connected to a “Type J” Jack Assembly or
companies that manufacture resins and for incoming quality
equivalent.
control companies using these polymers as raw materials for
production. The method is based on the methods which were
7.6 “TypeJ”DoubleConductor,B&SGaugewirewithpoly
previously outlined in the Handbook of Reinforced Plastics,
insulation and color coding (white for positive/red for nega-
“Procedure for Running Exotherm Curves Using the Block
tive) to connect “Type J” thermocouple needle to recording
Test Method” published by the Society of the Plastics Industry.
pyrometer or equivalent.
6. Interferences 7.7 Electronic Balance, suitable for accurate weighing to
0.01 g and a minimum capacity of 200 g.
6.1 The results obtained are often influenced by the type of
resin used, the age of the resin, the age of the initiator and the 7.8 Machined Centering Device, for centering thermo-
type of initiator used. Care shall be taken to ensure that the couple needle within the resin sample. This device is made
chemicals used are stored and used in accordance with the from reinforced plastics, micarta, or other suitable material.
manufacturers’ guidelines. See Fig. 1 for the set up of the device.
FIG. 1 Machine Centering Device for Thermocouple Assembly
D7029 − 17
7.9 Beaker (150 mL), made of glass or plastic. 14.3 Add 100 6 0.02 g of the temperature adjusted resin
into the 150 mL beaker containing the initiator and styrene
8. Reagents and Materials
monomer, if used (for Type I and Type II initiators, but it is
possible that Type III initiators will not require any styrene),
8.1 Styrene Monomer, with 15 6 5 ppm of Tertiary Butyl
and mix thoroughly, being careful to entrap as little air as
Catechol (TBC) Inhibitor.
possible into the mixture.
8.2 Initiator Type:
14.4 Let beaker stand for 15 6 5 min at approximately 77°F
8.2.1 Type I—98 % Benzoyl Peroxide crystals.
(25°C) prior to running the test.
8.2.2 Type II—Benzoyl Peroxide paste/emulsion with a
tolerance of 6 1.5 % of the specified concentration with a
14.5 Pour the initiated resin from the beaker into the test
maximum of 18 % water. Example: 40 % benzoyl peroxide
tube so that 3.00 6 0.05 in. (76 6 1 mm) of the resin is in the
with a range of concentration from 38.5 to 41.5 %.
test tube.
8.2.3 Type III—Initiat
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7029 − 09 D7029 − 17
Standard Test Method for
Determination of Reactivity of Unsaturated Polyesters and
Vinyl Esters at 180.0°F (82.2°C)
This standard is issued under the fixed designation D7029; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This standard provides a standardized test method for determining the gelation and exotherm curve of unsaturated polyester
and vinyl ester resins. This method provides guidance for measurement of the “Standard 180°F (82.2°C) Exotherm Curve” along
with information on potential variances of the measurement which may be required for for some special resins. This test method
provides information concerning the reactivity of unsaturated polyester and vinyl ester resins as they go through polymerization
after mixing with the initiator.
NOTE 1—There is no known ISO equivalent to this standard, although ISO 584 is similar.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system mayare not be exact necessarily equivalents; therefore, each system shall be used independently of the other. Combining
values from the two systems may has the potential to result in nonconformance with the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
2.2 Society of Plastics Industry, Inc.:
Handbook of Reinforced Plastics “Procedure for Running Exotherm Curves Using the Block Test Method”
2.3 ISO Standard:
ISO 584 Reinforced Plastics Based on Unsaturated Polyester Resins—Determination of Reactivity at 80°C
3. Terminology
3.1 Definitions—For definitions of terms that appear in this practice relating to plastics, refer to Terminology D883.
3.2 Definitions:Definitions of Terms Specific to This Standard:
3.2.1 gel time—the period of time in minutes and seconds required for the recording pyrometer to go from a temperature below
(usually 10 to 30°F or 5.5 to 16°C) bath temperature to 10°F (5.55°C) above the bath temperature, typically 150°F (65.5°C) to
190°F (78.8°C) for a bath at 180°F (82.2°C).
3.2.2 cure time—the period of time in minutes and seconds required for the recording pyrometer to go from a temperature below
(usually 10 to 30°F or 5.5 to 16°C) bath temperature to the maximum temperature reading, typically 150°F (65.5°C) to the
maximum temperature for a bath at 180°F (82.2°C).
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.18 on Reinforced Thermosetting
Plastics.
Current edition approved Sept. 1, 2009July 15, 2017. Published September 2009August 2017. Originally approved in 2004. Last previous edition approved in 20042009
as D7029 - 04.D7029 - 09. DOI: 10.1520/D7029-09.10.1520/D7029-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7029 − 17
3.2.3 interval time—the period of time in minutes and seconds required for the recording pyrometer to go from 10°F (5.5°C)
above the bath temperature to the maximum temperature reading, typically 190°F (78.8°C) to the maximum temperature. Thus,
interval time is cure time minus gel time.
3.2.4 peak exotherm—the maximum temperature reached during the testing.
3.2.5 recording pyrometer—a broad class of temperature measuring devices including thermocouples with the ability for
continuous temperature recording.
3.2.6 initiator—a compound that generates free radicals to start the free radical polymerization of the unsaturated polyester and
vinyl ester resins. It is typically a single peroxide, but a combination of initiators could be used.
3.2.6.1 Discussion—
An initiator is typically a single peroxide, but there are instances in which a combination of initiators is used.
4. Summary of Test Method
4.1 Polyester or vinyl ester resin is mixed with the initiator(s) in a beaker causing a polymerization of the resin to occur. Heat
will accelerate the polymerization reaction. The exotherm generated by the resin as it cures is measured using a thermocouple. The
curve is plotted and the time to reach various temperatures along with the peak temperature obtained (peak exotherm) is
determined. The initiator normally employed to generate the test results is benzoyl peroxide, although the method may be used is
valid with other initiator systems.
4.2 The test method is useful in providing information about the heat generated during cure of the resin and the length of time
the resin remains in the liquid state prior to polymerization into solid form.
5. Significance and Use
5.1 This test method is used to measure the reactivity of different lots of unsaturated polyester and vinyl ester resins. The
information provided by this test can beis often used for assessing the predicted performance of a resin when used in elevated
temperature as part of the process used to convert the resin into a finished product.
5.2 The method is used in research and development by companies that manufacture resins and for incoming quality control
companies using these polymers as raw materials for production. The method is based on the methods which were previously
outlined in the Handbook of Reinforced Plastics, “Procedure for Running Exotherm Curves Using the Block Test Method”
published by the Society of the Plastics Industry.
6. Interferences
6.1 The results obtained can beare often influenced by the type of resin used, the age of the resin, the age of the initiator and
the type of initiator used. Care shall be taken to assureensure that the chemicals used are stored and used in accordance with the
manufacturers’ guidelines.
6.2 Control It is possible that the control of the bath temperature and the circulation within the bath canwill affect the results
of the test. Care shall be taken to control the bath temperature and agitation to comply with the method instructions.
7. Apparatus
7.1 Recording Pyrometer, Iron Constantan, 60 in. (1.5 m) per hour charts speed or equivalent.
7.2 Thermometer, with divisions every 0.1°F (0.05°C) capable of reading a minimum of 180 6 1°F (82.2 6 0.5°C) or
equivalent.
7.3 Constant Temperature Water Bath, or alternate media bath capable of being controlled to 180 6 0.5°F (82.2 6 0.2°C) with
an agitation rate of 1 to 2 times the bath capacity per minute. The bath shall have a minimum capacity of 2.5 gal (8.8 L) an shall
be fitted with a cover with access holes for the bath heater, thermometer, and test tubes in order to minimize evaporation of water.
7.4 Borosilicate Glass Test Tubes, of 19 mm diameter and 150 mm length with plain end and lip.
7.5 “Type J” Thermocouple Needle, made from 304 stainless steel, 6 in. (152 mm) in length, with an outside diameter of ⁄8
in. (3.2 mm) connected to a “Type J” Jack Assembly or equivalent.
7.6 “Type J” Double Conductor, B&S Gauge wire with poly insulation and color coding (white for positive/red for negative)
to connect “Type J” thermocouple needle to recording pyrometer or equivalent.
7.7 Electronic Balance, suitable for accurate weighing to 0.01 g and a minimum capacity of 200 g.
7.8 Machined Centering Device, for centering thermocouple needle within the resin sample. This device may be is made from
reinforced plastics, micarta, or other suitable material. See Fig. 1 for the set up of the device.
D7029 − 17
FIG. 1 Machine Centering Device for Thermocouple Assembly
7.9 Beaker (150 mL), made of glass or plastic.
8. Reagents and Materials
8.1 Styrene Monomer, with 15 6 5 ppm of Tertiary Butyl Catechol (TBC) Inhibitor.
8.2 Initiator Type:
8.2.1 Type I—98 % Benzoyl Peroxide crystals.
8.2.2 Type II—Benzoyl Peroxide paste/emulsion with a tolerance of 6 1.5 % of the specified concentration with a maximum
of 18 % water. Example: 40 % benzoyl peroxide with a range of concentration from 38.5 to 41.5 %.
8.2.3 Type III—Initiator(s) mutually agreed upon by laboratories running the test.
8.3 Unsaturated Polyester and Vinyl Ester Resin.
8.4 Silicone Grease.
9. Hazards
9.1 Initiators such as benzoyl peroxide must be stored in accordance with manufacturers’ guidelines. Failure It is possible that
failure to do so canwill result in the materials becoming unstable causing fire or explosions.
9.2 Directly mixing Do not mix metals like cobalt and other chemical with the initiators can create init
...