Possibly one of the most informative videos about epoxy and gelcoat bonding on KZread. Take a bow, you earned it!

I am SSPC certified and we did a lot of testing like this which you demonstrated very well. We do almost the same but using meters designed to tell exactly how much load is needed to cause separation failure. There was no significant difference in adhesion test between poly and epoxy using gel coat. Technically gel coat isn't a structural polymer anyway so it did fine cosmetically on both. The only major differences we noticed was in structural tests. Poly and epoxy did seperate in thick structural lay ups. Each one being a 1/4" or better. However we did calculate it would take years for the two to self delaminate. The two resins cure differently, break down differently, and each one flexs differently over time which causes some of the problem. Gel coat would be fine given proper prep on the epoxy just as you did. Removing the blush and a very good mil profile for adhesion. Also allowing the gel coat to cure properly and not rushing the curing process which allows the off gas and blush to settle on top and not between the substrate. Love your channel and keep up the awesome work! You rock!

@boatworkstoday

8 жыл бұрын

+Frankie Eubanks Great explanation Frankie! Thank you ;-)

@mhmdgad9129

6 жыл бұрын

thank you very much for the comment but may i ask Is it true that poly sinks deeper in the wood than epoxy and is more flexible ?

@TammyNorie

4 жыл бұрын

Thank you very much for this explanation. One thing that worries be about Andy's (otherwise excellent) quick tests is that they only look at the results the next day, and we know that curing and breakdown takes years. Your results make a lot of sense: avoid structural lamination with resins with different properties. That does make me reconsider making epoxy repairs to polyester hulls too.

@patricksawyer5525

3 жыл бұрын

can gel coat be coloored

@firstmkb

2 жыл бұрын

Mhmd Gad I saw a tip in the West System user guide for better penetration on the surface, or below it (cracks or holes). Pre-heat the wood or other substrate, and when you apply epoxy the heat will thin it a little before it cures. Thinning with acetone would weaken the epoxy.

Great vid. when I bought my Allied Mistress in 1988 it had a 2ft by 4ft hole burnt through the starboard bow, I repaired it with the West system and new glass finished with about 1/16 th of jelcoat. Though I painted with Imron 5 yrs. ago the repair is still holding! Have done sim. repairs on other boat since and have had no problems. Keep up the good work, Bill Read/Manitoulin Marine.

Great video , as a shipwright that has repaired Terra yachts that are built with epoxy with a gelcoat skin I never experienced a delaminated of the gelcoat 👍

Great job! I have been thinking about how to put gel-coat over epoxy for a while. Now I'm not afraid to do it. As always it's all in the prep.

thank you for taking the time to run this test, great info.

An outstanding effort to make reasonable and understandable tests, let alone the West System follow-up! I am 100% convinced now that for my needs any of these adhesives would be suitable, and it is time to give up my Elmer’s glue. Seriously, people can opine on this one way or another FOREVER, but a solid demo cuts that down. Thanks!

The trick is the amine blush. I did a large hull repair on a 22' McGregor sail boat laminating the glass with epoxy. On the inside I used auto body bondo (polyester based) for fairing. I did not wash off the amine & it prevented the polyester putty from curing at the interface. The rest of the putty hardened just fine, but at the surface where the two met, the putty never cured. It stayed soft & could not bond. I fully expected to see a bonding failure here & was surprised. Take away is wash the blush off, ie prep properly!

I used the west system on a outboard cowling and then applied a polyester fairing putty. This was before learning that it's not recommended. My cowling turned out fantastic and the putty adhered just fine. This video is proof that polyester bonds to epoxy with the proper prep. Thanks for the video.

Absolutely the best Epoxy with gellcoat informative video I've watched,if not the only true,barefacts most helpful.i can now move forward with one of my projects,many thanks Elliott.

Thanks for your time and effort to demonstrate this principle. Very reassuring to know epoxy is fine to gelcoat over.

Thank you for the great information. I will need all the help I can get, I'm restoring an old 1950s cuddy cab my first restore . I will be watching you and your videos.

Very helpful tests as I am in the midst of a small boat repair AMF Sunfish from 1979. The center most middle of the keel has cracking, scrapes, and small holes from abuse, rocks and who knows what. I have applied a first coat over these areas using West Systems 105 and 205. Cured overnight and sanded. No glass strips applied - just the epoxy resin. I am planning to apply at least two more coats. The next one with Silica mixed in. The third just straight epoxy again(as with the first). I will sand between layers. Thank you for your videos!!! (6/12/23) Last step will be applying Gelcoat with Wax.

Great video Andy, for the test preformed, it seems as the epoxy will hold gelcoat. Thanks for doing these test.

Awesome test! I was taught to never ever layup gel coat on epoxy, but its hard to argue with test results. Thanks for doing the test.

Brilliant! Thank you for sharing your practical research. You have provided very useful information indeed. Cheers!

Thank you for your due diligence. I will have no hesitation to use gelcoat over epoxy.

I built my water tanks on my 40 ft saiboat out of epoxy glass. After a week of curing I cleaned the surface with soap and water followed by acetone. I coated the surface with off the shelf gelcoat. I had numerous uncured spots of a square inch or two here and there. I can only attribute that to inadequate mixing or possibly resin to hardener ratio slightly off. After sanding out the uncured areas and re-coating with gelcoat, the areas cured fine. After a few weeks of curing, I filled the tanks with water. It has been 2 years since and the water has had no smell or taste issues. I coated with gelcoat to avoid bisphenol a contamination of the water. Yes, gelcoat over epoxy works. Mixing your final coat of epoxy properly and thoroughly is very important as I found out.

I always wanted to do that test....great job

Thanks! I’ve been ignorantly slapping gel coat over epoxy for years, and only recently learned you shouldn’t do it. I don’t recall having any problems with it. Yeah, a good cleaning and coarse sanding probably makes the difference. Thanks for the test!

Cool test Andy, interesting results. Not being a boat guy, I don't work with these materials, but I love learning about it! Happy New Year!

Congratulations! Absolutely superb video! I've been in the marine industry for over 15 years now working with boatbuilders. Thank you very much for clearing up this old myth!!

@fishhuntadventure

3 жыл бұрын

Not sure you can call it a myth. Flex properties, molecule adhesion, and unequal expansion/deformation at various temperatures are real concerns. Hence Andy’s tests: “will gelcoat work?” It appears it does but that doesn’t mean in structural application or sectioned repairs that you should just ignore the ‘myths’ and I don’t hear AndyBT suggesting that. This was a gelcoat eval test only.

I have watched all your videos and they are very informative and well presented. If the purpose of gelcoat is to give a super smooth glossy finish is there an epoxy based product that will do the job as well as polyester based gelcoat?

Love the videos! Wish to see more! Ive been restoring my boat and yhe fiberglass videos have been very helpfull.

I realize this video was done a couple of years ago however, I'm new to your channel having just found it today (03/10/2018). I've been in & around the Autobody trade all my life as my Dad was in the trade before me. We were always taught gelcoat over epoxy was a no no, don't even think about it. Well I strayed & went into the Canadian Armed Forces & am today a disabled Vet that custom designs & builds RC vehicles & boats. I gelcoat my boats but want to fiberglass the hulls (not always wooden hulls btw, metals, glassed, foam) to save time in joint sealing getting a better looking hull in my opinion. Thus your tests & demostration interested me greatly (as does your channel btw) & I was still wanting to gelcoat my glassed hulls etc, but was nervous about trying it. Now tho, I am ready to go ahead & I'm certain I'll get excellent reults in performance & looks which obviously is of paramount interest to my clients who commission me to design & build their boats. To the point I believe I can acheive as good of results as full size boat makers acheive, a long time goal of mine. Excellent video & TY very much for sharing your tests, as a new sub your channel is very interesting overall.

Great job as usual, very informative 👍

Thanks for taking the time to save us some time Great channel

Getting the amines cleaned off and a good ruffling is the trick. I've been doing t this way for years.

The flex & tension test is good and all but what about heat/temperature. Temperature can reach over 100 degrees. And what about the salt water? I must say, the poly/epoxy gelcoat test was very interesting .

Great video, thanks very much for the information.

Thanks Andy!

GREAT JOB ! DO more tests very good !

Great test. Thank you

Thanks for this video. I patched some medium size holes using west systems epoxy and gel-coated as a finish. It's beautiful and incredibly strong. Caught a lot of slack from "traditionalist". Most important step is to wash the epoxied areas to get rid of the byproduct created during the curing process.

@richardwise350

Жыл бұрын

when you wash it, do you just wipe clean with water on a rag or use acetone or some other product to clean the surface?

@alixbarks

9 ай бұрын

@@richardwise350 I always wash well cured epoxy with tepid water and a splash of ammonia, normal household cleaning ammonia. Then rinse with tepid water and a splash of white vinegar, normal kitchen white vinegar. Remember your high school chemistry: Amines are base, epoxy hardeners even smell of ammonia. Ammonia dissolves the amines. Vinegar, an acid, neutralizes the ammonia. Squeaky clean surface. You can feel the difference. Then sand to get the mechanical tooth. Cheap and simple. Maximize chance of success.

all of your videos are great. thanks for all the help with my projects. there's something I don't understand though, isn't gelcoat finished over fiberglass on pretty much all boats? I'm sure there's something I'm missing, any clarification would be appreciated. Also, do you have any gel coats you like working with, what are some brands you trust?

Thanks for the nice video. I want to finish a large area of fiberglass with epoxy. Gel coat seems to be a good option. Would it be a good idea to use peelply on the last epoxy coat, to avoid having to wash the amine blush and sanding?

I did not even knew this so I just used topcoat on my epoxy repairs and it actually did bond very well, same as this conclusion you have, not even west system but another European brand.

Great video. I'm preparing to restore a 1988 Ranger 363V and watching this video makes me wonder if I could apply epoxy over a well sanded gunwale that has so many cracks in the gel coat that grinding out and filling would be more trouble than its worth. I was thinking I could sand it all down, epoxy, and gel coat over the epoxy and that the epoxy would keep the original gel coat from re-cracking. What are your thoughts?

Yes it will work, Gelcoat Over Epoxy, we used that method in the Philippines fisherman Banka Boat works just find. . .

Great vids. Isn't the only difference between hardeners is the 'speed' at which they cure?

Awesome test nr3! Thanks a lot.

I wonder if the expansion and shrinkage with temperature variations will delaminate the gelcoat from the epoxy. Separating the gelcoat sandwich experiment did not secure the flexion on both substrates, epoxy and poly was the same. The piece flexing the mist will release first.

great video on a taboo subject. Being in the trade I have often said the difference between a pro and a hobbyist is when something out of the ordinary is brought up, a hobbyist says "oh noooo that would never work" while a pro says "Try it" . Thanks for "trying it" and Im going to "try it" on a job I am currently doing. Great work!

@boatworkstoday

8 жыл бұрын

+705techno Thank you!

@kevinlivingston9563

6 жыл бұрын

Can fiberglass be laminated to plastic?

@an_what

6 жыл бұрын

705techno taboo?

Très apprécié, very appreciated.

Another awesome video!!

Get your fingers out of there! when using a flat bar, you can get alot of torque and leverage by actually putting your bar closer to the work, and then pushing/pulling on the side and putting force on at 90 degrees of where you typically think if applying force. This puts the torque on the edge of the tool rather than where the bend is. A good helpful video. Thankyou.

Loving your efforts to teach, very clear and precise. And the little voice at the end of all your videos always brings a smile to my face. Dam cute :). Was wondering if you could do a video on the secret of avoiding the dreaded 'halos' in gelcoat?

@boatworkstoday

9 жыл бұрын

john stannard Will do :-) Right now I am knee deep in painting but next gelcoat project I get I'll put something together!

Great video! I agree with the comments about exposure and saltwater testing. It would also be interesting to see how the samples stand up to UV exposure since the vast majority of boats are left out in the sun. I wonder if the bond would lessen after a year in the sun? Would the typical yellowing of UV exposed epoxy have any effect on the color of the gelcoat over time?

solid video, Thanks!

This is so great. Thank you very much!!

Have seen this fail when gelcoat is applied to a mold, the fabric laid up with epoxy (don't know which one) & the finish product submerged. Some years later the gelcoat bubbled off the epoxy. This was on dagger boards, where the board was out of the water for most of time, it was fine, just the submerged part bubbled.

What I've found gel-coat/flowcoating polyester over expoxy is that it has the same result that you experienced in the short term. However after a couple of years it starts to blister and when sanded, the edges always show a lip which means, as you were looking for in your samples, a lesser adhesion. What are others experiences?

Is that balsa marine ply? Where did you get it? I think it's worth noting that the ply layers didn't separate and the quality of the wood is equally important. Thanks for sharing

I just used total boat close cell phone and total boat epoxy resin to raise the level of my anchor locker level with the drain. I always understood epoxy should not be gel coated. Is it ok to leave epoxy resin without gelcoat in a wet area? Many thanks and thanks for these great videos.

It would be interesting to check the bond on the gel coat 2 years later .

Have you ever done a series on gelcoat blisters? Below and above the waterline. The causes and repairs. Thank you.

@Bakanelli

10 ай бұрын

I would be also SUPER interested about that!!!! Randy @boatworkstoday PLEASE PLEASE make video about poly blisters! 🙂⛵⛵⛵

Thank you... So much.

Awesome channel, some guys who swore what you just proved opposite may come to give you a beat, LOL. keep the good work. BTW is there a similar way to make epoxy more "sandable" and less clogging the sand paper?

Pretty good test design. I wonder what parameters could be changed to replicate the bonds in a marine environment.

the problem with this video is that the gel coat/epoxy is new . show a video of how gelcoat adheres to epoxy long term, after repeated uv/sun exposure and temperature expansion.when I was still in the biz, I've "cheated", and while it had good short term results, but not long term, and I prepped everything right. vinylester gelcoat works much better for me. great videos , dude!

When epoxy cures it has a layer of wax that rises to the top. This helps (but doesnt entirely stop it) moisture from getting caught in the curing. Wax is almost if got just as good as plastic for creating a non stick layer.

hey awesome video would you put wax in the gelcoat before applying it?

Very help full Man. You teached me allot.👌👍👍💯

Great video! I would love to see these tests performed on the same samples after a year of salt water exposure. For example, you could hang the samples from a dock to expose them to cycles of water and air. That is one variable not addresses here, which I feel could have an effect on the long term happiness of the two materials.

@boatworkstoday

9 жыл бұрын

zumafa That was one of the things that had to be edited out of the video :-/ I'm planning to throw the samples outside for a year and do a follow up vid on the durability. I don't have any salt water in Wisconsin, buy I do have huge swings in temperature and moisture :-)

@DeadeyeLefty

7 жыл бұрын

FWIW, I did this to make a plywood canoe. I scarfed the plywood planking with thickened epoxy and then tabbed over the scarf with epoxy and knytex. After that, I sheathed it in mat and poly resin. Adhesion was fine, since the epoxy was well cured and well prepped. I used it on the west coast for a few years, then put a deck on it (a 'canak') for a few more...then it got antifouling and became a temporary float for the end of a dock for the next 5 years or so. When I finally replaced it with styro billet, I cut it up to go to the dump. The ply was in good shape but the solid wood I used for gunnels etc was rotting away. When I cut through the scarfs with a sawzall, it still behaved as one solid piece - there was no delam at all. That project was also a test for pigmenting epoxy with carpenters' chalk - it worked perfectly.

@jaredsmith4893

7 жыл бұрын

So how did they hold up after a year?

Nice set up and tests. I really liked the bonding polycoated and epoxy coated and then applying gelcoat between them. Very informative. I have used System 3 Surfboard epoxy (amine free) as a tie coat between West Epoxy and Gel Coat. No sanding but for max bond you have to lay down the gelcoat 15 hours after the epoxy. The nice thing about the Surfboard epoxy is it flows and flattens itself for a very smooth finish to lay your gel coat onto. Nice to know that the 207 will work as well.

I know that this will not be a fair comparison, but would you be willing to try wet poly resin, on one layer of fiberglass, then a film of wet get coat on top of that, and then allow it to cure with a one layer on top of fiberglass already cured with epoxy and 207 hardener ? I am curious to know if the chemical bonding of poly resin with the gel coat would be stronger than the strongest bond you got between gel coat and epoxy cured with 207. By the way, I have learned a ton with your very informative videos, God bless you for it, and a BIG thank you!

Darn great video. For my 2cents you proved PVC and epoxy both work exactly as I expect them too, and are very good components. Nice to have trust in your material I was surprised somewhat on the bending they all worked better than I would have guessed. Good work!

How would fairing compounds work with the epoxy and gelcoat? And what fairing compound would you use on top of epoxy

Hey, just curious. Did you do any follow up / aged samples to account for off gassing differences between the different resins?

Thank you...conflicting information abounds and this clears it up!

Good video, thank you. Question: Why are you still using an epoxy that produces an amine blush? The problem of amine blush was formulated out so many years ago, Wonder why West hasn't kept up with technologies from decades ago? For the people that don't deal with it properly, it can be a real issue.

would have loved to see poly resin and gelcoat next to those

Do you think it would bond just as well if there was a fairing coat in between? The epoxy with 410 filler doesn't seem like it would bond nearly as well, but maybe it should be mixed with polyester resin at that point.

How about re-tabbing a bulkhead wall to wood, epoxy or polystyrene?

Interesting results! Thanks for sharing. Perhaps this "myth" came to be from inferior epoxies of "yesteryear", for a lack of a better description. I'd imagine that these days, production processes have improved tremendously.

Great tests. I have done gelcoat repairs over epoxy and held my breath, too. This is very useful information. Were you using Styrene Wax in the gelcoat application?

@boatworkstoday

9 жыл бұрын

F18Capricorn No wax; just laminating gelcoat that I sealed off with PVA to allow a full cure :-)

Well i used Gelcote over epoxy on a swing keel rebuild. It lives underwater from. May to nov6 and on a trailer in sib freezing temperatures all winter so no problems except from grounding the keel. I slso read directly off the label on the can dont use with epoxy. Not sure why nit it seems to be kust fine.

Would you ever try this with total boats system since you switched over to it

cool stuff; i appreciate your experimental design and think the results were informative!

@boatworkstoday

7 жыл бұрын

Thank you Ian! Really appreciate it ;-)

Busted!

Would be interesting to see a comparison between penetrating epoxy and homemade penetrating epoxy. Do you shun penetrating epoxy? Is it because you're unable to replace the core afterwards?

Awesome, educational video... thank you for taking the time to make it. I wonder if you could answer a question for me. For some strange reason, the fiberglass battery box in our recently purchased RV had the bottom cut out, and then reinforcement installed to hold up the bottom back in place. I want to repair it back to original using the 1708 fiberglass. The base of the battery box is approximately 18" x 18". The bottom needs to support the @ 150 pounds of battery weight; 2 deep cycle 6-volt batteries. Would three or four layers of the 1708 fiberglass be sufficient to support the batteries? Thank you.

@JustinSmith-il8vg

4 жыл бұрын

Just be safe and double whatever you think will be sufficient. Make sure grind & bevel 5 or 6 inches up the side wall and wrap your glass up the sidewall. If you can access the bottom side, then you should wrap it as well

Interesting test, it's great to see people challenging the mainstream opinions and winning ;-) How do you think this would apply to an Epoxy resin infusion were gelcoat was laid into a female mold and the an epoxy laminate infused over the top after it was cured? Given the saying 'epoxy over polyester but not polyester over epoxy' I would think it would be ok but again I'm hearing everywhere that it can't be done. How much does it depend on the type of Epoxy vs type of gelcoat etc. The only epoxy compatible gelcoat I can find online says it can't be submerged in water. Not much good for a hull!

@rogermccaslin6750

5 жыл бұрын

You would have problems doing what you suggest (gelcoat mold and then infuse with epoxy). Gelcoat is what is commonly referred to as air inhibited. What that means is the surface in contact with air doesn't fully cure. You can feel it for yourself. It's that slightly tacky surface even though the gelcoat is hard. Poly and VE resins have the same issue (just in case anyone is curious). That tacky, semi-cured surface great for laminating with polyester or vinylester resin as it allows a chemical bond to take place. However, that same thing that makes it great for bonding to poly and VE is exactly what makes it terrible for epoxy. The chemistry of the two materials don't play well together. There will be a thin layer of goo between the two materials. Please note, this is not the same as what has been demonstrated in the video - the bonding of a cured surface with a different resin chemistry.

This helped Me as well but ,I think I would be more comfortable with putting a 2K urethane primer over top of fiberglass first ,is that OK to seal it off before using white gel coat,I'm still having hard time on uses best on floor ,if gel coat will work ,why use primer first ? maybe I will see another video first that might answer this for Me ,thanks again .Jim

Is it possible to infuse epoxy over cured polyester iso gelcoat?

I was told by west system that one should wait 18 days before putting gelcoat on epoxy?

Andy, I've watched your posts and truly enjoyed them. I also watched a video out of the UK and they talk about adding styrene I think is what they said. Is this a UK thing?

@boatworkstoday

9 жыл бұрын

Terry Brothers no, it's pretty common :-). It's basically a thinner that evaporates without changing the color of the gel.

What brand gel coat did you use for this testing. Also, would it still be your recommended the same gel coat today? If not, what are you using these days? I will be some transom repair over west system 205.

could you please help me I bought boat which is painted. I sow that under the pain boat have beutiful galcoit. How I can cleaN COLOR AND POLISH GALCOIT. tHANKS

Wow that was cool

hi,what do you think about the home depot resins and auto stores bondo resin?

Have you done this same test with Total Boat epoxy?? If so what was the outcome? Thanks!

hello, one question i dont understand did you use gelcoat or topcoat because gelcoat will be never totally dry always sticky , right ?

good test. do a test of not properly preparing epoxy and coating. In other words, not doing what you say and then test it for adhesion etc.

Did you ever get results from West Systems? Or am I failing to see the video with that update?

Is there any way you take on projects such as restoring a full boat? I have a 1990 bankcroft, it is wooden hull and in terrible conditions. People keep telling me right and left what to do but everyone has a different approach every time and contractors charge over 30k. Would you take on a project like this or would know who?

Based on your excellent video, I was going to roll on gelcoat over my epoxy fiberglass deck. But before I did, I did some tests on 1 sq ft areas and the result was that the gelcoat did not fully harden on 50% of the area it was applied to. Moreover, the 50% area that did harden, took 5 days to harden. I did three tests over the epoxy deck and 9 tests over unepoxied plywood boards. The gelcoat was 30 days old and the epoxy was RAKA 127/606 applied 4 years earlier, long ago cleaned of amine and sanded with 80 grit for the test and cleaned. I also found that the gelcoat also did not harden over 3 year old pine knots on the plywood tests and did not harden over a pine board that was shellac or lightly varnished 20 years ago. West Systems says you can apply gelcoat over epoxy, Andy BoatworksToday showed one can apply gelcoat over West System epoxy, but my results were not good. Bottom line, gelcoat over epoxy may be a brand by brand hit or miss. We know West System epoxy and gelcoat worked for Andy, but we do not know what brand of gelcoat he used. I think we need to know what brands of gelcoat and epoxy work together. I used Fiberglass Supply Depot White un--waxed gelcoat and RAKA 127/606, and it didn't work.

@quale1345

2 жыл бұрын

There are other contributing factors in your testing. Gelcoat is notorious for being difficult to fully cure even on polyester. Proper mixing, freshness of the catalyst, temperature and humidity are all to be considered.

@alixbarks

9 ай бұрын

Gelcoat over epoxy in small~ish patches is maybe okay, given this test. But for any large area, like your whole deck, why mess with gelcoat? Go for paints over large area epoxy repairs. Gelcoat was designed for inside a female mold, i.e. no oxygen, and not self-leveling. [note all test samples excluded gelcoat open to air.] Why bother on large surfaces?

Dam the 206 is the way to go !!

Maybe you should explain the differences between the hardeners

Excuse me is there anyway I could actually get in touch with you I have a few fiberglass questions that I need a professional to help me answer what . I feel like the information I've got not the internet is not 100% accurate not to mention you are a boat Craftsman and what I'm building right now is a boat. I was lucky enough to get a fiberglass boat . Given to me and now I'm getting ready to start working on it but I'm having some issues before I even get started . In long story short I would I would love if I could maybe get you on like a zoom call or something and just get maybe like 10 or 15 minutes of your time if that's possible you're knowledge is extremely valuable to me