{"id":3020,"date":"2022-09-15T15:41:07","date_gmt":"2022-09-15T19:41:07","guid":{"rendered":"https:\/\/www.bottompaintstore.com\/blog\/?p=3020"},"modified":"2026-01-27T12:44:18","modified_gmt":"2026-01-27T17:44:18","slug":"how-to-apply-professional-grade-exterior-gelcoat-by-brush-and-roller","status":"publish","type":"post","link":"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/how-to-apply-professional-grade-exterior-gelcoat-by-brush-and-roller\/","title":{"rendered":"How to Apply Gelcoat by Brush and Roller"},"content":{"rendered":"<p class=\"post-updated\"><strong>Last Updated: January 27, 2026<\/strong><!--?php echo get_the_modified_date('F j, Y'); ?--><\/p>\r\n<!-- Quick Recommendation Box: Applying Professional-Grade Gelcoat by Brush & Roller -->\r\n<div class=\"bps-quick-reco\" style=\"border: 1px solid #e5e5e5; border-left: 6px solid #0a6fb5; background: #f8fbff; padding: 16px 18px; margin: 14px 0 22px; border-radius: 8px;\">\r\n<p style=\"margin: 0 0 8px; font-size: 13px; letter-spacing: .06em; text-transform: uppercase; color: #0a6fb5; font-weight: bold;\">Quick Recommendation<\/p>\r\n<h2 style=\"margin: 0 0 10px; font-size: 20px; line-height: 1.25;\">How to Apply Professional-Grade Exterior Gelcoat by Brush &amp; Roller<\/h2>\r\n<ul style=\"margin: 0; padding-left: 18px; line-height: 1.6;\">\r\n<li><strong>Best for smaller areas and repairs:<\/strong> Brushing and rolling <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> works well when spraying isn\u2019t practical or permitted.<\/li>\r\n<li><strong>Prep and mix precisely:<\/strong> Clean, de-wax, sand thoroughly, and <strong>measure <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a> accurately<\/strong> to avoid curing issues.<\/li>\r\n<li><strong>Apply thin, even coats:<\/strong> Use quality rollers\/brushes and build thickness gradually, sanding lightly between coats if needed.<\/li>\r\n<li><strong>Bottom line:<\/strong> You can achieve a <strong>professional, durable <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> finish without spraying<\/strong> by focusing on prep, mix ratios, and controlled application.<\/li>\r\n<\/ul>\r\n<p style=\"margin: 12px 0 0; color: #555; line-height: 1.5;\"><strong>Tip:<\/strong> <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">Gelcoat<\/a> won\u2019t fully cure in open air\u2014use a <strong>wax additive or PVA<\/strong> on the final coat, then wet-sand and polish for a smooth finish.<\/p>\r\n<\/div>\r\n<p>&nbsp;<\/p>\r\n\r\n<p><a href=\"https:\/\/www.bottompaintstore.com\/fiberglass-and-gel-coat-repair-gelcoat-c-13581_13586.html\/filtered\/module_id:87\/[f-23-197]Application%20Method:Sprayable?sub_category=1\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"URL\" data-id=\"https:\/\/www.bottompaintstore.com\/fiberglass-and-gel-coat-repair-gelcoat-c-13581_13586.html\/filtered\/module_id:87\/[f-23-197]Application%20Method:Sprayable?sub_category=1\">Professional Grade Exterior Gelcoat<\/a> can be applied either by Spraying, Brushing or Rolling. This article will discuss how to apply the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> with the brush and roller method. For a more comprehensive guide on How to Apply <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">Gelcoat<\/a>, <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/how-to-apply-gelcoat\/\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"URL\" data-id=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/how-to-apply-gelcoat\/\">please read this article.<\/a> We will assume you have already read the article to learn about prepping the surface, sanding, and finishing the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a>.<\/p>\r\n\r\n\r\n\r\n<h2 class=\"wp-block-heading\"><strong>Catalyzing Gelcoat with MEKP<\/strong><\/h2>\r\n\r\n\r\n\r\n<p>All gelcoats MUST be catalyzed with <a href=\"https:\/\/www.bottompaintstore.com\/MEKP-Catalyst-for-Gel-Coat-and-Resin?search=mekp&amp;description=true&amp;sort=relevance&amp;order=DESC\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"URL\" data-id=\"https:\/\/www.bottompaintstore.com\/MEKP-Catalyst-for-Gel-Coat-and-Resin?search=mekp&amp;description=true&amp;sort=relevance&amp;order=DESC\">MEKP<\/a> to cure. This should be added after all other additives just prior to application. We suggest 1-1\/4% to 1-1\/2% by volume, i.e. 13-15 cc per quart. We do NOT recommend mixing more than 1 quart at a time. Darker colors need a little more <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">catalyst<\/a> for the same reaction, so you can catalyze those up to 2%. All Gelcoats purchased from the Bottom Paint Store come with <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a>. Refer to the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">catalyst<\/a> chart located on the product page, the product label, or the one below.<\/p>\r\n\r\n\r\n\r\n<figure class=\"wp-block-image\"><img loading=\"lazy\" decoding=\"async\" width=\"760\" height=\"660\" class=\"wp-image-3026\" src=\"https:\/\/www.bottompaintstore.com\/blog\/wp-content\/uploads\/image-1.png\" alt=\"\" srcset=\"https:\/\/www.bottompaintstore.com\/blog\/wp-content\/uploads\/image-1.png 760w, https:\/\/www.bottompaintstore.com\/blog\/wp-content\/uploads\/image-1-300x261.png 300w, https:\/\/www.bottompaintstore.com\/blog\/wp-content\/uploads\/image-1-624x542.png 624w\" sizes=\"auto, (max-width: 760px) 100vw, 760px\" \/>\r\n<figcaption>One gallon of polyester resin weighs approximately 9.2 lbs. One gallon of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> weighs approximately 10.5 lbs.<br \/>The weight of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a> 925 is 1.125 grams per cc. 30 drops is approximately equal to one cc.<br \/><br \/>cc = cubic centimeter. Oz = fluid ounce<br \/>Note: Using drops for <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">catalyst<\/a> measurement is only an estimate. In critical applications <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a> should be measured \u00a0using cc\u2019s or fluid oz\u2019s which are volume measurements.<br \/>The percentages in the chart: 1% thru 2%, are percentages of resin or <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> by weight. The cc and oz values in the chart have been converted from weights of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a> to volumes of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a>.<\/figcaption>\r\n<\/figure>\r\n\r\n\r\n\r\n<div class=\"wp-block-group\"><div class=\"wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow\">\u00a0<\/div><\/div>\r\n\r\n\r\n\r\n<p><strong>NOTE:<\/strong> \u00a0The <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">catalyst<\/a> level (<a href=\"https:\/\/www.bottompaintstore.com\/MEKP-Catalyst-for-Gel-Coat-and-Resin?search=mekp&amp;description=true&amp;sort=relevance&amp;order=DESC\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"URL\" data-id=\"https:\/\/www.bottompaintstore.com\/MEKP-Catalyst-for-Gel-Coat-and-Resin?search=mekp&amp;description=true&amp;sort=relevance&amp;order=DESC\">MEKP<\/a>) should not exceed 3.0% or fall below 1.2 for proper cure. Ideal range is 1.8% @ 77\u00b0F. Gel time at 1.8% <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">MEKP<\/a> is 10-17 minutes. This time element is dependent on material temperature, room temperature, humidity, air movement, and <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">catalyst<\/a> concentration. <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">Gelcoat<\/a> should not be used when temperature conditions are below 60\u00b0F, as curing may be adversely affected.<\/p>\r\n\r\n\r\n\r\n<p>Be sure to have a good strategy when applying your <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a>. Once you mix and catalyze, you have about 15 minutes to apply the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> before it starts getting hard or starts to\u00a0\u201cgel.\u201d The actual working time depends on the amount of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">catalyst<\/a> and how hot the working conditions are. Anything below 60 degrees, and your <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> will not cure, but as you get warmer and warmer, your working time will decrease rapidly. <strong>At 70 degrees, you get 15 minutes, but at 90 degrees, you only get 5 minutes.<\/strong><\/p>\r\n\r\n\r\n\r\n<p><strong>TIP: <\/strong>If you need more time to work, sit the can in some cold ice water to cool it down to 60 degrees to allow a little more working time.<\/p>\r\n\r\n\r\n\r\n<h2 class=\"wp-block-heading\"><strong>Application<\/strong><\/h2>\r\n\r\n\r\n\r\n<p><strong>Brushing:<\/strong> Use a solvent resistant brush. The chemicals in the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> can be harsh on materials not designed to withstand them. Using a solvent resistant brush should stop any brush materials from getting in the finished product.<\/p>\r\n\r\n\r\n\r\n<p><strong>TIP:<\/strong> Choose a natural bristle brush with tapered bristles that are not too stiff.<\/p>\r\n\r\n\r\n\r\n<p>Apply <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> quickly using long brush strokes to help achieve an even thickness and to help remove trapped air pockets.\u00a0 Load the brush fully with <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> each time. Applying the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> quickly will help you apply it to the correct thickness. <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">Gelcoat<\/a> applied too thin will not cure properly. Remember, this <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> has been catalyzed and the clock is ticking. Also, large amounts of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> left in the container allows a buildup of exotherm and causes the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> to cure too quickly. \u00a0Once all the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> is out of container and on the surface then you can spend time tidying up with the brush strokes.<\/p>\r\n\r\n\r\n\r\n<p><strong>TIP:<\/strong> Try to finish vertical areas with an upward brush stroke. This will help reduce sag.<\/p>\r\n\r\n\r\n\r\n<p><strong>Rolling:<\/strong> Use a solvent resistant 1\/8 or 1\/4 inch nap roller. Be sure not to use foam rollers; they tend to leave bubbles. Wrap the roller in painters\u2019 tape and rip the tape off to remove loose fibers from the roller. Apply the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> to the surface quickly. Remember, this <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> has been catalyzed and the clock is ticking. After wetting out a small area with the roller, use the tip of a brush to smooth out the stipple left by the roller. Move the brush in smooth strokes <strong>perpendicular<\/strong> to the direction that the roller moved. Be careful to not apply too much pressure during this step. Ask a friend to assist with the tipping to speed things along. When rolling or brushing on the second coat be sure to apply in the opposite direction from the previous coat. This allows for a uniform finish.<\/p>\r\n\r\n\r\n\r\n<h2 class=\"wp-block-heading\"><strong>Overview<\/strong><\/h2>\r\n\r\n\r\n\r\n<p>The 1<sup>st<\/sup> coat will consist of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> and <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">hardener<\/a> only. Wait a half hour for the <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a> to set. It should be tacky. It will not be fully cured yet.<\/p>\r\n\r\n\r\n\r\n<p>The 2<sup>nd<\/sup> coat will consist of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a>, <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">hardener<\/a>, and wax additive sanding aid. 1 oz of sanding aid per quart or 4 oz per gallon. Sanding aid seals the surface from oxygen, causing the surface to dry tack free.<\/p>\r\n\r\n\r\n\r\n<p>A wax additive is NOT used with <a href=\"https:\/\/www.bottompaintstore.com\/fiberglass-and-gel-coat-repair-gelcoat-c-13581_13586.html\/Clear-HI-UV-Exterior-Gelcoat\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"URL\" data-id=\"https:\/\/www.bottompaintstore.com\/fiberglass-and-gel-coat-repair-gelcoat-c-13581_13586.html\/Clear-HI-UV-Exterior-Gelcoat\">HI UV Clear<\/a>. You should only use a wax additive in the final application coat or if you are planning on applying only one coat.<\/p>\r\n\r\n\r\n\r\n<p>If you followed all the steps correctly you should have a beautiful application of <a href=\"https:\/\/www.bottompaintstore.com\/blog\/gelcoat\/gelcoat-did-not-cure-what-caused-it-and-whats-next\/\">gelcoat<\/a>! If you\u2019re using our <a href=\"https:\/\/www.bottompaintstore.com\/fiberglass-and-gel-coat-repair-gelcoat-c-13581_13586.html\">Professional Grade Exterior Gelcoat<\/a>, you\u2019ll be ready to sand and buff your freshly gelcoated surface after about 1- 3 hours.<\/p>\r\n<script type=\"text\/javascript\" charset=\"utf-8\" src=\"http:\/\/w.sharethis.com\/widget\/?wp=6.9.7\"><\/script>","protected":false},"excerpt":{"rendered":"<p>Last Updated: January 27, 2026 Quick Recommendation How to Apply Professional-Grade Exterior Gelcoat by Brush &amp; Roller Best for smaller areas and repairs: Brushing and rolling gelcoat works well when spraying isn\u2019t practical or permitted. Prep and mix precisely: Clean, de-wax, sand thoroughly, and measure MEKP accurately to avoid curing issues. Apply thin, even coats: [&hellip;]<\/p>\n","protected":false},"author":817,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[7],"tags":[620,621,430,433,619],"class_list":["post-3020","post","type-post","status-publish","format-standard","hentry","category-gelcoat","tag-applying-gelcoat-with-a-brush","tag-applying-gelcoat-with-a-roller","tag-brushable-gelcoat","tag-mekp","tag-professional-grade-gelcoat"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/posts\/3020","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/users\/817"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/comments?post=3020"}],"version-history":[{"count":11,"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/posts\/3020\/revisions"}],"predecessor-version":[{"id":4134,"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/posts\/3020\/revisions\/4134"}],"wp:attachment":[{"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/media?parent=3020"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/categories?post=3020"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bottompaintstore.com\/blog\/wp-json\/wp\/v2\/tags?post=3020"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}