Prosecution Insights
Last updated: April 19, 2026
Application No. 18/206,897

FLAME RETARDANT WOOD, PREPARATION METHOD THEREOF AND USE OF METAL HALIDE

Non-Final OA §102§103
Filed
Jun 07, 2023
Examiner
WEDDLE, ALEXANDER MARION
Art Unit
1712
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Northeast Forestry University
OA Round
5 (Non-Final)
63%
Grant Probability
Moderate
5-6
OA Rounds
3y 2m
To Grant
90%
With Interview

Examiner Intelligence

Grants 63% of resolved cases
63%
Career Allow Rate
584 granted / 927 resolved
-2.0% vs TC avg
Strong +27% interview lift
Without
With
+26.8%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
58 currently pending
Career history
985
Total Applications
across all art units

Statute-Specific Performance

§101
0.9%
-39.1% vs TC avg
§103
43.5%
+3.5% vs TC avg
§102
15.7%
-24.3% vs TC avg
§112
32.5%
-7.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 927 resolved cases

Office Action

§102 §103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Continued Examination Under 37 CFR 1.114 A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 5 February 2026 has been entered. Claim Rejections - 35 USC § 102 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claim(s) 11 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Burgert et al. (US 2017/0043497). Regarding Claim 11, Burgert et al. (US’497) teach a fire retardant wood containing calcium chloride and treated by impregnation [0157,0169]. The specific preparation steps, including setting an atmospheric pressure condition between vacuum treatments, is not given significant weight, for the wood, impregnated with a solution, including calcium chloride and/ or calcium bromide. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claim(s) 1-5 and 14-16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Burgert et al. (US 2017/0043497). Regarding Claim 1, US’497 teach a preparation method of fire retardant wood, comprising: impregnating a wood with a salt solution (calcium chloride, CaCl2; calcium bromide, CaBr2), during which a vacuum treatment is carried out for a plurality of times, wherein a salt in the salt solution is a fire retardant and is one or more selected from calcium chloride and calcium bromide[0169,0008,0099]. US’497 fails to teach an atmospheric pressure condition is set at a period between two adjacent vacuum treatments; however, the suggestion in US’497 to perform vacuum impregnation several times would have suggested a release of vacuum between each of multiple vacuum cycles. Thus, it would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of US’497 by releasing the vacuum in between cycles of vacuum impregnation (i.e. “an atmospheric pressure condition is set at a period between two adjacent vacuum treatment”). Regarding Claim 2, US’497 suggests applications of fire retardant wood in construction and production of furniture and the process, includes liquid solvents, including water and an alcohol (Table 1; [0081]) and can include a semi-finished wood product or a component [0122]. US’497 fails to teach a drying process. However, it is obvious that US’497 expects that at least some fire retardant wood will be used in applications that require wood dried at least to some extent (with typical moisture content of dried wood used in construction applications). Thus, it would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of US’497 with a drying process at some point between the impregnation method and the use of wood as a construction material, including for furniture. Regarding Claim 3, US’497 fails to teach drying wood. However, drying wood at atmospheric pressure (e.g. on racks off the ground and under tarpaulins outside or inside) is conventional in the art to achieve a wood product with a desirably low moisture content for a particular construction application. It would have been obvious to dry wood at atmospheric pressure, because such drying conditions are typical for wood products. Regarding Claim 4, US’497 fails to teach drying wood at a temperature ranging from 20 C-30C. However, 20C-30C is typical outdoor temperatures and it is conventional to dry wood under such normal outdoor temperatures to achieve a desirable moisture content. It would have been obvious to dry wood at within 20-30C, because such drying conditions are typical for wood products. Additionally, temperature and drying time are related, and it would have been obvious to a person of ordinary skill in the art at the time of invention to modify drying temperature in order to achieve a desired drying time. Also, generally, differences in temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such temperature is critical. Regarding Claim 5, US’497 teaches a concentration of CaCl2 of about 5.5% (0.5 M*110.98 g/mol÷1000 g/L). Generally, differences in concentration will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration is critical. Regarding Claim 14, US’497 teaches 1-4 cycles of vacuum impregnation and a time of impregnation cycles which last from 2 to 24 hours [0145,0152-0154,0161], including specifically cycles of 2 hours [0164]. US’497 fails to teach 10 cycles or specifically 5 hours. US’497 provides evidence that time is a result effective variable, known in the prior art to affect mass gain and degree of mineralization [0162,0164-0165] It would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of US’497 by adding additional cycles at a duration within the recited range to ensure adequate treatment and to optimize times to achieve a desirable extent of reaction and/ or of impregnation. Where US’497 teaches impregnation in cycles, additional cycles is prima facie obvious duplication of steps. MPEP 2144.04. Regarding Claim 15, US’497 fails to teach a salt concentration of 20%. Generally, differences in concentration will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration is critical. Moreover, it would have been obvious to modify solution concentration in order to ensure adequate treatment with an expectation of some loss of treatment salt during treatment. Regarding Claim 16, the recited temperature range of 20-30C is a conventional range of temperature for drying wood and loss of water weight through evaporation is directly related to time of drying at typical temperatures. Claim(s) 18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Burgert et al. (US 2017/0043497) as applied to Claim 1 above, and further in view of Bailey et al. (US 7,640,664). Regarding Claim 18, US’497 teaches treatment of beech, spruce, and ash, but does not particularly limit treatment to those species. US’497 fails to teach poplar or tung. Bailey et al. (US’664) is analogous art in the field of treating wood with fire retardants and is pertinent to Applicant’s problem of treating wood. US’664 teaches impregnating a wood panel with a fire retardant, including a metal salt (zinc chloride) (col. 9, lines 40-56; col. 10, lines 21-31) and suggests that the wood panel comprise woods from trees including a wide variety of broadleaf trees (e.g. ash, aspen, spruce, buckeye, butternut, beech, birch, black cherry, chestnut, cottonwood, elm, hack berry, hickory, honey locust, black locust, maple, oak, sycamore, walnut, and yellow poplar) (col. 16, lines 10-25). It would have been obvious to a person of ordinary skill in the art at the time of invention to modify the invention of US’497 by impregnating wood from a broadleaf tree, including a poplar, because US’664 suggests impregnating a wood panel made from trees, including those varieties of trees, with fire retardant to obtain a fire retardant panel. Claim(s) 1-5 and 14-16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Depew et al. (US 2,838,424) in view of Burgert et al. (US 2017/0043497). Regarding Claims 1, 17, and 18, Depew et al. (US’424) teach a preparation method of fire retardant wood, comprising: impregnating a wood with a salt solution (zinc chloride) (col. 1, lines 55-64). US’424 additionally teaches that multiple cycles of impregnation can be used (col. 2, lines 61-66), including an initial vacuum treatment, followed by increased pressure at 125 psig (about 8.5 atm), followed by a vacuum (Figure), which requires “an atmospheric pressure condition set at a period between two adjacent vacuum treatments,” since as the pressure changes from 125 psig of positive pressure to 22 inches of vacuum or in reverse, it necessarily passes through a condition of atmospheric pressure. US’424 fails to teach calcium chloride or calcium bromide as a metal halide for the treatment of wood. US’497 is analogous art in the field of wood treatment, including by impregnation with fire retardants. US’424 teaches a preparation method of fire retardant wood, comprising: impregnating a wood with a salt solution, not only such as ZnCl2 as in US’424, but also including calcium chloride (CaCl2) and calcium bromide (CaBr2), during which a vacuum treatment is carried out for a plurality of times, wherein a salt in the salt solution is a fire retardant and is one or more selected from calcium chloride and calcium bromide to achieve adequate mechanical and fire-retardant properties [0169,0008,0099,0161]. Thus, it would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of US’424 by impregnating with calcium chloride and/ or calcium bromide in addition to or as a substitute for zinc chloride to achieve desirable mechanical and flame-retardant properties. Regarding Claim 2, US’424 teaches a drying process (col. 1, lines 55-64). Regarding Claim 3, US’424 teaches atmospheric pressure (“air dried”) (col. 5, line 55 to col. 6, line 1; col. 6, lines 40-42). Regarding Claim 4, US’424 teaches drying wood at a temperature of 35° C (col. 6, lines 23-43). US’424 fails to teach drying between 20 and 30 ° C. However, temperature is known in the prior art to affect drying time. It would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of the combination of US’424 in view of US’497 by adjusting drying temperature to within the recited range through routine optimization. Also, generally, differences in temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such temperature is critical. Regarding Claim 5, US’424 teaches the salt solution comprises zinc chloride in a concentration of 20% (col. 7, lines 21-25). US’497 teaches a concentration of CaCl2 of about 5.5% (0.5 M*110.98 g/mol÷1000 g/L). It would have been obvious to a person of ordinary skill in the art at the time to include calcium chloride in the recited amounts, because US’497 suggests the concentration is sufficient to achieve desired properties (mechanical and fire retardancy). Generally, differences in concentration will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration is critical. Regarding Claim 14, US’424 teaches applying a vacuum a) initially to remove residual air from pores in the wood (col. 4, lines 2-4) for five to ten minutes (col. 5, lines 46-47) and b) to force excess liquid from pores in the wood (col. 3, lines 70-75; col. 4, lines 8-9). US’497 teaches 1-4 cycles of vacuum impregnation and a time of impregnation cycles which last from 2 to 24 hours [0145,0152-0154,0161], including specifically cycles of 2 hours [0164]. US’497 fails to teach 10 cycles or specifically 5 hours. US’497 provides evidence that time is a result effective variable, known in the prior art to affect mass gain and degree of mineralization [0162,0164-0165]. It would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of the combination of US’424 in view of US’497 by adding additional cycles at a duration within the recited range to ensure adequate treatment and to optimize times to achieve a desirable extent of reaction and/ or of impregnation. Where US’497 teaches impregnation in multiple cycles, additional cycles is a prima facie obvious duplication of steps. MPEP 2144.04. Regarding Claim 15, US’424 teaches the salt solution comprises zinc chloride in a concentration of 20% (col. 7, lines 21-25). The combination of US’424 in view of US’497 fails to teach calcium chloride or calcium bromide in the recited concentration. Generally, differences in concentration will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration is critical. Moreover, it would have been obvious to modify solution concentration in order to ensure adequate treatment with an expectation of some loss of treatment salt during treatment. Regarding Claim 16, US’424 teaches drying wood at a temperature of 35° C (col. 6, lines 23-43). US’424 fails to teach drying between 20 and 30 ° C. However, temperature is known in the prior art to affect drying time. It would have been obvious to a person of ordinary skill in the art at the time of invention to modify the process of the combination of US’424 in view of US’497 by adjusting drying temperature and time (e.g. time as a function of temperature) to within the recited ranges through routine optimization. Also, generally, differences in temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such temperature is critical. Claim(s) 18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Depew et al. (US 2,838,424) in view of Burgert et al. (US 2017/0043497) as applied to Claim 1 above, and further in view of Bailey et al. (US 7,640,664). Regarding Claim 18, US’424 teaches impregnating generic wood. US’424 fails to teach a species of wood. US’497 teach treating beech, spruce, and ash in particular [0152], but does not particularly limit wood species. US’664 is analogous art in the field of treating wood with fire retardants and is pertinent to Applicant’s problem of treating wood. US’664 teaches impregnating a wood panel with a fire retardant (col. 9, lines 40-56; col. 10, lines 21-31) and suggests that the wood panel comprise woods from trees including a wide variety of broadleaf trees (e.g. ash, aspen, spruce, buckeye, butternut, beech, birch, black cherry, chestnut, cottonwood, elm, hack berry, hickory, honey locust, black locust, maple, oak, sycamore, walnut, and yellow poplar) (col. 16, lines 10-25). It would have been obvious to a person of ordinary skill in the art at the time of invention to modify the invention of the combination of US’424 in view of US’497 by impregnating wood from a broadleaf tree, including a poplar, because US’664 suggests impregnating a wood panel made from trees, including those varieties of trees, with fire retardant to obtain a fire retardant panel. Response to Arguments Applicant's arguments filed 05 February 2025 have been fully considered but they are not persuasive. In response to Applicant’s argument that calcium chloride and calcium bromide provide unexpected results (Remarks, p. 5-7), Burgert et al. (US 2017/0043497) teach calcium chloride and calcium bromide as fire retardants for treatment of wood by impregnation. Evidence that calcium chloride and calcium bromide provide unexpected results as fire retardants of wood impregnated with solutions of those salts is not given significant weight, where US’497 teaches impregnating into wood solutions with these specific salts as fire retardants. Even if Applicant recognizes other advantages of calcium chloride or calcium bromide as a wood impregnant, the art specifically teaches these salts as impregnating solutions for wood for fire retardancy, even if they have additional advantages. If calcium chloride and calcium bromide have better smoke suppression as a property of those compositions in preserved wood, they also imparted better smoke suppression to wood in prior art wood treatments, which impregnated wood with solutions containing them, whether or not the property was recognized. Conclusion No claim is allowed. Any inquiry concerning this communication or earlier communications from the examiner should be directed to ALEXANDER M WEDDLE whose telephone number is (571)270-5346. The examiner can normally be reached 9:30-6:30. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Michael Cleveland can be reached at 571-272-1418. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. ALEXANDER M WEDDLE Examiner Art Unit 1712 /ALEXANDER M WEDDLE/Primary Examiner, Art Unit 1712
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Prosecution Timeline

Jun 07, 2023
Application Filed
Aug 22, 2024
Non-Final Rejection — §102, §103
Oct 29, 2024
Response Filed
Nov 09, 2024
Final Rejection — §102, §103
Jan 15, 2025
Request for Continued Examination
Mar 05, 2025
Response after Non-Final Action
Mar 06, 2025
Non-Final Rejection — §102, §103
Jun 10, 2025
Response Filed
Aug 04, 2025
Final Rejection — §102, §103
Nov 05, 2025
Response after Non-Final Action
Feb 05, 2026
Request for Continued Examination
Mar 06, 2026
Response after Non-Final Action
Mar 07, 2026
Non-Final Rejection — §102, §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

5-6
Expected OA Rounds
63%
Grant Probability
90%
With Interview (+26.8%)
3y 2m
Median Time to Grant
High
PTA Risk
Based on 927 resolved cases by this examiner. Grant probability derived from career allow rate.

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