Can CSM (Chopped Strand Matting) Be Used With Epoxy??

[@theotherfinnegan9955]

hi Andy. appreciate the tutorial but I thought you'd be filling holes on the console today.

[@boatworkstoday]

Just got back from SC last night, was gone all week visiting Alexseal HQ in Charleston! Video's about that will be coming up soon, as well as getting back on track with the Bertram!

[@franklindmurphy]

That’s what I was waiting for! 😆

[@walter2990]

Whew! I was wondering this very same thing (filling holes in console), but was hesitant in asking you about it! I'm actually redoing a console at this time, and I'm "hanging" on every video you make about it. Thank you for doing these tutorial videos! I really need to open my copy of the Fiberglass 101 workbook that I bought from your website, but was having problems with my PC & printer (fixed now). Peace!

[@walter2990]

One more question: Is there any concerns if we use poly over the new brand of flexible epoxy "putty" that you used to fill in the cracks on the Bertram's gunnels? We keep hearing "E over P, only" Thanks!

[@Rainman9753]

Andy, I live in Charleston, SC and wonder what you thought of our city and harbor?...any thoughts? Also, by this thread, sounds as if we all have some console projects abound. Yay!

[@t____g____5606]

Best restoration boat channel on youtube.

[@jjbailey01]

Best fiberglass restoration channel. Lots of his vids apply perfectly to fiberglass RV restoration as well.

[@walkertongdee]

Here in Asia much of the resin Polly and Epoxy come with no mono styrene so neither will wet out any glass. You have to really understand resin formulation to use it at all. We just add mono styrene to both and all is well... If you want to use epoxy with matt just add mono styrene four parts resin to one part mono styrene. All glass needs to have the binder dissolved to work well be it weave or matt.If you want the epoxy to get in all those nooks and crannies you need mono because all glass has a binder.

[@DaveGagliardi]

THIS ^^^ I was wondering if you could just add, or pre-wet the CSM with a styrene based solvent to aid in the wet out. Maybe this would allow for using epoxy on styrene adhered CSM? I'd really like to know!

[@poepflater]

thanks for teaching me something, the local styrene I can find suggests 2 -5% though... do you really need 20%?

[@mfournier12]

Not all woven mat has a binder as the fibers are long woven fibers they stay together like all woven fabrics without a binder. CSM has a binder of some type to hold the short randomly oriented fibers together. epoxy compatible CSM is labeled as such and uses a powder binder that doesn’t need a solvent to break it down. But yes your 100% correct styrene is required with to resolve the binder in most CSM or bonded woven mat.

[@charlesschuster7963]

comments from a longtime surfboard builder, also some boat work... It cannot be over-emphasized that the builder should wet the surface to receive the CSM before applying the CSM. This way, 1) the CSM is held in place and doesn't fall off the surface (if you've worked on vertical or overhead surfaces it will become immediately apparent; 2) the CSM will wet out from both sides rather than just the top; 3) the surface wetting will help fill the substrate which may otherwise absorb resin and leave the glass too dry. 3 isn't usually an issue when working with CSM but can be with woven product. Less resin = stronger (generally) finished product. other item niggling point... the dry glass product doesn't "absorb" resin. The resin displaces air between the fibers or yarns. I call it "wetting out" rather than "absorbing". But overall a good point about the sizing used on glass fibers.

[@richardvargas9224]

Andy, you sir are a master of your craft. Thank you so much for teaching those of us that aren't as well exercised in boat repair I live watching your videos.

[@skyboat345]

Man your channel is a goldmine for those taking their first steps in boatmaking

[@johngregory4801]

Baltek told me years ago that I couldn't use epoxy with CSM because of the styrene binder... But I had no idea that stitched fabrics with CSM, such as 1708, didn't have that binder. Thank you for clearing that up!

[@SailLife]

Awesome video as always, Andy! :)

[@gking5522]

A clear, concise explanation and graphic demonstration of a simple, but important, fact of life in laying up plain, chopped strand mat only. For those who didn't know the whys and wherefores, you and I do now! A New class next week I presume, same time, same channel. I'll be there! Thanks Professor G King, SV Intuition

[@markrichards3810]

Epoxy vs poly is always like a ford vs chevy debate lol, Im running my boat 2 more seasons b4 a substantial rebuild and almost complete restoration and these videos have helped me immensely on what products and how and when to utilize them,,now when someone tells me only use epoxy or vise versa i can give them the "scientific "reason why and actually know what im talking about!LOL,once again thankyou so much,this is my favorite thing to watch on KZbin! Thankyou andy!...best boat vids on KZbin hands down!

[@CheersWarren]

Andy, that was a good demo for the basic diy guy but as someone who has been in the boat and industrial fiberglass industry for 40 years a couple of points. Glass is not all the same. There are glass products made for different resins. Glass has a variety of 'sizings' added to them to make them easier to process , like the woven cloths have different sizing (think lubricants for the weaving machinery) than the stitch mats, like 1708 or the CSM. Many of these sizing are washed off or heat removed. The cloths in particular commonly used for epoxy military laminates can have coatings added to enhance the wet out of the fibers to get the required epoxy resin to glass ratio required ( ignoring pre-preg laminates). Similarly for polyester resin different coatings can be used. But as you know stitch mats and cloth products have little to no binders so work ok with epoxy or poly resins for general purpose laminating. FYI continuous creels of 'roving' used to create the chopped fibers, with a 'chopper gun' used for some production fiberglass work have different sizings on them to help the product run thru the equipment before it is fed into the chopper head. The fiber binder(glue) used on CSM you correctly point out is made for polyester/styrene monomer resins. Over the years the binders have improved , powder bound and water based are just 2 varieties and provide different properties. But they all require the styrene to dissolve them to allow full wet out of the fibers as the binder can get deep into the tiny glass fiber bundles. If you use epoxy resin with a binder bound glass (CSM) it will not dissolve the binder so will not fully wet out the glass , the bundles of glass will not wet out with epoxy. This is one of the main reasons your epoxy laminate was not wet out properly. Also there are other coatings on the CSM made to help the poly resin properly wet out the fibers after the binder has been broken down. In the same way some cloths have coatings to assist the wet out of just epoxy resins. The other thing that effects the wet out is ,of course, the viscosity and thixotropic properties of the actual resins. Epoxy resin are by their chemistry not possible to make with the same easy workability as polyester resins, (read easy wet out) hence why the hi strength epoxy laminates are all done using combinations of heat and pressure for the ultimate properties. For general boatbuilding open laminating the increase in properties from epoxy are mainly limited to the improved secondary bonds to substrate IF proper preparations are done. But I am with you, that for many applications quality polyester resins will produce better results in a diy situation because of the superior workability of the materials. Cheers Warren

[@rogermccaslin6750]

I've also been in the industry for a long time (35+ years). Another point that is overlooked is that the sizing on the glass helps to enhance the adhesion of the resin to the glass fibers. As I understand it, some sizings are compatible with both epoxy and styrene based resins. Others are made for a specific resin chemistry. In the grand scheme of things, I don't know how much difference it makes as far as laminate physicals are concerned but my take on it is to just use compatible materials. You get more efficient wet out, possible resin savings (as shown in the video), and ultimate laminate physicals. Why take a chance on future problems if you can avoid them with something as simple as proper material selection?

[@davidwheeler3232]

You do understand that these demonstrations are not really for the experienced fiberglass worker they are for the beginner and weekend warrior making minor repairs or such. So he is dumbing it down for us. I am an electrician and this would be like me trying to explain electrical theory to someone who doesn't understand it. I've been behind the weekend electrician and wouldn't want to live in their house. I wouldn't want to ride in the boat built by most weekend fiberglass techs either. These are skilled trades and require years of training to be done correctly.

[@18ftLyman]

I would hate to recommend something really regarded as poor application especially because some very knowledgeable techs add their thoughts to these offerings. People studying these videos are looking for first answers for the most part, or perhaps concurrence to favorite proprietary methods. That being said, the applications of these materials is subject to wide variation, particularly in repair work. In the work I've done, the choice between epoxy or polyester has always been properties of workability and strength in the final product. Everything Andy is saying about the epoxy is generally true, and the greater adhesion of the epoxy is a large attraction for it. Also, when being applied, it has good workability in the presence of moisture. It's a great choice for a properly cleaned bilge or a concrete deck. The problem is, would you buy a supply of e-glass to do a small job, or take a chance on polyester, using off your roll of poly-compatible mat. There is a way to compromise and still get an acceptable job: solvent. Yes, it's true that you will reduce strength characteristics and 'e' number by using solvents with epoxy, but you can double the laminate on a patch, and a deck done with epoxy and a tiny bit of solvent lasts 20 years or more; the typical concrete house deck isn't subject to dynamic stresses. I've used toluene, lacquer thinner or acetone for the thinner with best results using toluene. The key is to use the smallest effective amount, and to use extra glass if needed in successive layers like the video By the way, the milkyness in the glass sample above is air, not somehow cloudy resin. If entrained air is left in the laminate, two problems can arise; pinholes from the entrained air coalescing when your back is turned, and generally weak laminate. Using solvent you get a translucent laminate almost as quickly as with polyester. The other problem with fine bubbles in the laminate is that the bubbles grow into large voids around radiuses and angles where the glass is fighting back to lay flat. So, you choose your poison; which set of properties do you want to deal with, and are you willing to accept one set of results over another.

[@kevinmorris9712]

Hopefully one of you guys can help me. I have to use epoxy due to the outer layer (about 1/8 inch) being acrylic. I need it to be as strong as possible and lay down because it's the nose of a jet ski and has contours. I have csm and 1708. Using West System 105 with 205.

[@LearningtheLines]

Very interesting. I had never heard not to use CSM with epoxy. Great explanation and demonstration as to why you shouldn't. I'd love to see the strength test!

[@thomasfinchio1362]

Andy with my project I will be going over some rigid insulation.I belive Polly will distort the insulation board. Could I put one layer of epoxy to seal it And then go with the Polly?

[@Bakanelli]

@@thomasfinchio1362 how did it go?

[@davinernsberger9899]

I am sure you have mentioned this in other videos but this one kind of put a lot of the pieces together and after just reading your Resin guide this all makes sense now. thank you and keep up the great work you do for the boating world.

[@MrCantakaris]

Answered the number one question I’ve had for a long time! The only place I’ve seen/heard the answer about 1708 and epoxy 👍 Thank you, great video....as always 👏👏

[@chadchorniak1407]

It might be helpful for viewers to see the entire process before they made a decision. Having to use PVA for curing and re-sanding before reapplication could be deciding factors. Epoxy is stronger and if pin rolled between each layer would produce a stronger layup in my opinion. Vinyl is much cheaper. Also, the strength difference may not be enough to sway one to use the epoxy. Great video. Thank you for your efforts.

[@shigatsuningen]

Seems to me, being a layman, that you would have to hardroll every layer when using epoxy in order to get rid of any and all air bubbles. Secondly, I would be curious to see if you could get ahold of EU-glas to compare.

[@JAR2.0]

Andy, I did indeed find this video very helpful. Getting to the core of these kinds of topics is critical to underling the best practice approach to working with fiberglass. More of this type of video will be welcome at my home shop. Thanks!!!

[@josephjones9372]

NOW you tell me!!! LOL. I have never worked with fiberglass or epoxy and of course I start with a life size statue I made out of paper mache. I had an extremely hard time getting the fiberglass mat to stick and it mostly stuck to the brush only. What a pain! I tried fabric and it worked much much better. I have watched many of your videos and they have been SO helpful, especially for a beginner. Thank you so much!

[@valentineattard2344]

Excellent information given, you educated me and stopped me from spending a boat load of money on the wrong glass. Thanks

[@clflyguy]

Hello Andy, I've found that a heavier initial wetout of the primary surface (wood panel) and bubble rolling of each successive layer overcomes these "problems" quickly and easily. It's too bad that European mat is so expensive here in the states.. Nice demo, thank you.

[@wisenber]

West Systems suggests using a release fabric or 4 mil plastic to thin out the layup and remove bubbles. It's an extra step, but it's workable if you're wanting to avoid having some parts poly and other parts epoxy on the same boat.

[@sailingteresaway8492]

Andy - Thanks for this. Can you explain the compatibility of epoxy and poly? If doing a major (or minor) deck core replacement and you don't know what resin was used on the existing boat, what do you suggest to do?

[@notsponsored103]

"It just looks happy" makes perfect sense to all of us who've had success and failure with glass laminating. Love your videos, so helpful.

[@trusten2]

Thanks for that demo. I've heard you tell us not to use epoxy with chopped strand, but now I really know why.

[@barryford6795]

Andy worked in a commercial boat manufacturing plant built the hulls out epoxy resin skin the hull out with stranded mat never had a problem. Strength wise hull was stronger due to using epoxy resin and the scheduled lay up of glass. The engineers always said because of the epoxy resin it created a lighter and stronger hull.

[@sgrasmick82]

As assumed! Epoxy is way stronger than poly.

[@Driendel]

Epoxy is always the best option when it comes to fiberglass boats, no matter what type and strand of fiberglass you use. Especially if you use S type fiberglass, even in chop strands.

[@D2O2]

Andy, thank you for making this video. There definitely is a fair amount of confusion out there on this topic. You cleared it up very well.

[@Tore_Lund]

Neat trick stumbled upon the other day: Wheat flour as thickening agent with epoxy. Not as lightweight, but stronger than micro balloons. It looks like custard!

[@kimyoung230]

Thanks Andy! I was watching this, thinking about a 17:08 epoxy layup I did a few years ago on some structural knees of my sailboat. Although the repair has worked just fine, I was getting worried, watching the video, about the strength of the repair. Felt better after you mentioned 17:08 at the end!

[@ryanrabdau5615]

I used epoxy and the first thing I thought was “wow it needs a lot of epoxy” now I know why. I will try polyester and compare. Great info for sure!

[@GoofieNewfie69]

Have used epoy with chop many times. The trick is , you must fin between layers. In your demonstration, if you had finned between layers, you would not have had to use extra epoxy. Yes , it is more work but thats what you have to do if you want to use epoxy

[@miscellania9876]

Hi, what do you mean by "fin" between layers, sanding? Thanks!

[@jkg6211]

@@miscellania9876 He means rolling each layer of CSM with a Fin Roller prior to adding the next layer.

[@zanelorimer4030]

Thankyou very much for helping me with decision on epoxy resin over polyester resin. Used polyester repairing boats in past and local panel repairer talked me down over suggestions on polyester repairing.

[@blackdog1234567890]

Andy, can you also comment on the advantages/disadvantages of using epoxy vs poly resin for laying up fiberglass. you have awesome videos. Thank You

[@fsj197811]

That was a really cool video, thank you. It's the counter point of "Why can't I?" "Because I said so." Well done!

[@floridasaltlife]

HOORAY, new video !!!! :) great topic, I am the exact guy you described in the lead ! Went from clear as mudd to clear as a bell, Double Thanks for producing these videos.

[@steveburton5825]

I would be interested to see a strength test.... I'd think you could put half of it over a workbench and then suspend a weight (like a bucket that you could fill with water or sand) on a rope tied through a hole cut say 1" from the end of the CSM... just keep adding until it breaks along the workbench edge (or pulls through the hole). You might want to do it outside though as it may make a mess when it fails!

[@NA-xm7wj]

A Rockwell hardness tester would work great as 1 part of a hardness test here

[@robertjackson7590]

@@NA-xm7wj West Systems have some really excellent tests with Epoxies and the big advantage they sell is a secondary bond isn't as strong with PER. Like a repair to cement, the repair can't cure as one solid piece so it's totally dependent on secondary bond. Epoxy does a much better job in that aspect. I replaced the floor in my 20 foot boat and found Epoxy grinds like Granite compared to PER. Far tougher In the end the the binders not breaking down make it hazy looking but don't affect the bond line, just appearance. I used a stitched matt 1708 wetted out clear and much stronger these layers of CSM by weight.

[@jmconnollyus]

This is tremendously helpful. I have always used West Systems Epoxy just because I guess. I've also used TotalBoat epoxy, but since I am a firm DIY'er, I kind of use what's on the shelf and West is much easier to source, albeit more expensive. All that being said, poly has always intimidated me a bit. I feel very comfortable with epoxy probably just because of familiarity. This video has done a lot toward demystifying polyvinyl resin for me. I know you've done a video in the past and will look for it, but how, when and can you use both poly and epoxy? Will they sit on top of each other? What would you say the top applications are for each? I've always thought of epoxy for structural uses -- hull repairs, etc. -- and the others for use in less "critical" areas or applications -- although none seem to come to mind. I love your videos -- your way of explaining complex things simply and understandably and your craftsmanship are incredible.

[@chuckebaker]

Andy- Great explanation of why epoxy is not ideal for CSM; clears it up for me (and now I know how often I've done it wrong). I used to teach a strengths of material class at Temple Univ and we would create simple set-ups for testing the strength of student projects. Let me know if you want some ideas on how to tests these to get comparable results.

[@stevenichols1861]

Thanks for the explanation. There was a guy with an actual fiberglass company who did a comparison saying poly is more porous and able to absorb water easier, and that it wasn’t as strong as epoxy. Is this more like a mechanic Vs. car engineer comparison where the guy actually using these products daily knows better from experience? 😂🤣😂

[@B._Smith]

Great video. Love the music and good audio production. Your in the class A team.

[@MrZachalewel]

Thank you for answering my 1708 csm question! Makes perfect sense

[@markusvalentin2722]

Hi Andy thanks for sharing your knowledge,in Seychelles we more polyester resin cause it easy application & easy access too

[@MrHelmuth1]

I have used the stitched chopped strand mat (for epoxy) from US Composites, it has no binder at all and works very well !

[@matthewmillar3804]

Thumbs up for a strength test! 😁

[@joelkoonce8559]

You da Man !!! Someday I hope to be half as good of a fiberglass Man as You are.

[@tribologist]

Thanks Andy! Way more relaxing than going to the movies! Have not done any composite work since i fixed an old whaler a few years ago where your videos were of phenomenal help. Patreon done.

[@varad17]

great demo.....I just made a couple of fiberglass panels for my boat and couldn't figure out why I was having such a hard time wetting out the chop strand matting compared to your previous videos....and yes...I went through a ton of epoxy resin in the process....woven matting wetted out much easier..to the point i vowed to never use chopped strand stuff again....this video explained why....if only this was out 3 weeks ago! I did have that metal roller to push out the excess resist and air bubbles though...what a awesome tool! That was from seeing you use them in your videos btw......

[@jimbarker730]

It helped me a lot ,because i was used to working with Cars ,like Shelby's & Corvette 's ,I was more able to picture it & since I was doing floors patches at one or two of chopped mat 5" by 8" on wood and fiberglass floor sections I believe it worked out well for me since I mixed it to slow dry in a day or longer depending on cool weather I',m having in east Texas outside ,I move boat in warm 68 70 degrees temp and back under shed at night seems to be OK ,keep up the great videos . Jim.

[@zakaroonetwork777]

Glad I found this... I had forgot about the Styrene Binder and almost used Epoxy.

[@combackiddd]

Very informative as always Andy. The demo made it very easy to finally understand.

[@JOEGGGJOE]

I totally agree with you on epoxy & chopped strand just don’t mix. I wish it did. Mixing epoxy creates some many bubbles, especially if you don’t degas it.

[@mewii_decks]

Thank-you Andy this was the exact question I have been thinking about for months, I needed this answer for my next job!

[@okcpicker]

Good explanation on using CSM with poly or epoxy. I am about to glass the interior of a water ballast tank which means all of my glassing will be upside down on the underside of the boat's floor. I was going to use epoxy with CSM but since I will be fighting gravity, it seems poly would be the best choice for absorption. (US made CSM)

[@lancehenthorn17]

If you Vacuum bag the repair. You would have no issues.

[@feshfeshsailing]

If you are about to glass the inner sides of your water tank, you're better off using epoxy (for longevity). But if you have only powder bound CSM and are forced to use PE resin, then at least apply an epoxy barrier coat to your laid up glass, or a coat of good iso or NPG gelcoat.

[@bipedalhominid6815]

1/10th ratio of acetone in your epoxy with dissolve the styrene binder. Once I figured that out I use epoxy with CSM all the time.

[@RodrigoNascimentoMattos]

amazing. thanks for this video. i´ve asked about this once. I can see you read your coments sections. regards from brasil. I´ve learned a LOT with this channel.

[@PaulHarold]

Super useful and practical information about glass and resins, thanks.

[@schoonerkiva]

Great explanation! Thank you. Just learning how to do this and everyone said you are the #1 source for info. They were right!!

[@sonofneptunesailing917]

YES. You just answered all of my questions!

[@marcstephan7650]

I only use epoxy on cloth. Poly will shrink 10 % and epoxy will shrink 1 %. You can put an epoxy piece back in the mold but poly project has distorted to where it will not fit well back into the mold. I work mostly with fiberglass cloth and carbon composite, that is why I use mostly epoxy. Plus exoxy will stick to metals where poly doen't so well.

[@spudpud-T67]

I use epoxy and CSM with great results, complete transparency. I use the powder bound CSM rather than the emulsion bound CSM which is not for use with epoxy. Emulsion bound is non compatible and never intended to be used with epoxy. It maybe some of your issues with epoxy and CSM may be because your seem to use the emulsion bound CSM for both. The epoxy will not dissolve the emulsion binder and allow the strands to move and settle. Emulsion and epoxy is a little like water and wax. I finished watching the video and you did explain this. However you need to source some powder bound CSM as it does seem to be widely available. I'm in NZ.

[@davidgale8333]

Thank you Andy you’re videos have taught me lot

[@dejayrezme8617]

Thanks, great informative video! So basically you can use CSM with epoxy if you get the right one with the correct binder. I wish you had made a third test! :)

[@NA-xm7wj]

Ok couple things here but first I’m new to fiberglassing 1 why did you not mention using pva or the finishing resin when you used the polyester resin 2 I was told by total boat technical guy specifically to use 1 teaspoon of hardener with 6oz of resin. I think you were doing 8oz batch in this vid and only used 25cc which is for lack of argument 1/2 of a teaspoon. Now here’s the question and you can ask for a email to further this conversation because I really am just trying to learn and have questions. But how did you arrive at 25cc of hardener for 8oz of hardener and I was told a teaspoon with 6oz of hardener

[@sailingvesselreimagined9433]

That’s a really good video. I was wondering about the 1708 and the chopped strand backing. Thanks Andy

[@Deubler]

"but don't take my word for it" Why though you explained the concept perfectly

[@jima4656]

It was previously my understanding that the old type of CSM used a binder that was not dissolved by epoxy, but composites like 1708 & modern CSM had a binder that did dissolve in epoxy. I guess that I need to keep my eyes open when buying CSM

[@glennwehmeyer]

There are Chopped Strand Matting that has cornstarch as a binder. Those can be used with either epoxy or polyester resins. But good demo of using standard CSM with epoxy.

[@reloadncharge9907]

Good video....solved it.....1708 only with my Total Boat or West epoxy products! Thanks, Andrew

[@robertbosman5398]

how about the otherway around polyester resin on fiberglas cloth what we usely use with epoxy ?

[@feshfeshsailing]

OK to use PE resin with CSM binded with all types of binders. But epoxy resin can only be used with powder binder CSM.

[@s7ev0]

I am in the UK and emulsion bound chop strand is the most common but you can easily get powder bound chop strand for use with epoxy. If you need the extra adhesion strength epoxy brings you would be stupid not to use woven for the strength as well.

[@przemyslawkrata3819]

Good job as always. Thanks Andy for sharing your knowledge and experience. I have one remark and one question. R) If you are willing to make a strength tests, please ensure you compare samples of the same weight. There is no point to test whether epoxy sample having the same amount of glass (as the poly sample) and an extra portion of the resin is stronger or weaker. Even homemade test might be valuable if carried out with physical basics taken into account. Q) I have heard many times about a sort of “osmosis” after a couple of years in case of laminating over wood with polyester resin. Only epoxy is usually found suitable for covering over wood. What do you think about it? What is your experience? Have you ever seen delamination of glass laid over wood with the poly resin?

[@kevinwegner7230]

I like this comparison. I've asked this question before, but never got a good answer. The visual is great with the Poly, which means it's probably lighter and stronger and costs less to do. Thanks!

[@marinoldus]

Thanks, I have to fix a big hole in my S2 8.0 sailboat hull. The hole was there for the OMC saildrive to stick out. Replacing it with a new 4 strole 9.8 outboard.

[@erynthegrey]

Andy, Acetone "melts" styrene. Can't you thin epoxy with a percentage of acetone to help melt the binder and increase saturation and bindability? (not a word, but you know what I mean.) Thanks!

[@nathanbutler8240]

If you mix acetone with it might not cure properly

[@markfrick6244]

Good point; however since it is recommended to use acetone to "clean" epoxy resin off of tools I would be concerned how it is breaking down the epoxy? Adding one chemical variable to a mix will change the compound? Since acetone "breaks" down the epoxy mix off of tools, not sure I would go that route? Then again I am NO expert 😀, but have to agree acetone will eat styrene!

[@feshfeshsailing]

Acetone is not to be used as an epoxy resin thinner. No, no, no Heck, you're not even supposed to use acetone to clean a surface before before laying up epoxy on it. Acetone leaves a thin film after drying that will reduce the quality of the bond between the surface and the laid up epoxy.

[@erynthegrey]

Fesh Fesh Sailing and yet, everyone does it. Even Andy. He has stated several times that is is an excellent degreaser it just evaporates too fast. Unless I am getting confused with some other chemical...

[@Rainman9753]

Thanks for the lessons Andy! Keep up the good work you do

[@redwood1957]

I would like to see the samples sliced then put on under a micro scope. I agree the appearance to the eye was more consistent with the poly. That said when using fast and slow set hardener it's also different to the eye. If I fill a hole and 2 weeks after I have no flexibility on the patch only time will tell. Thank you

[@brianjohnson5910]

So, I’m guessing that using regular epoxy could have been the bigger issue with my mat bridging on bends/corners? I had no clue I needed polyester resin until now. It’s been frustrating with the bridging. I’ve got some polyester now, so I’m going to see if that makes the difference. Hopefully I won’t be scrapping another attempted mold!

[@dheujsnrhfydhehehshshhdggsd]

Always prefer show don't tell. Thanks!

[@mickcoomer9714]

I’ve never done it that way round but I have used CF with a poly resin, not as anything requiring strength but just off cuts when mould making. Seems to work OK.

[@needlemiejer143]

im ordering resin for occasional auto repair fillin holes...im buying a gallon and the shelf life of poly is way shorter than epoxy...if epoxy WILL work im wondering if the tradeoff using strand is worth it considering not having to throw it away because of the longer shelf life

[@dennisdavidek6694]

1708 and epoxy is labor intense and time consuming. Said combination has caused me angst more than once.

[@sailingtheworld2021]

Thanks so much ... I have a rudder repair from running a ground with my prop chewing a bit of my rudder... I have no idea as I never fiber glassed a boat before. So I think, not putting words in your mouth if I stay with poly I should be okay. I was wondering if I need to paint over the epoxy when I am done or will just any foul do? Andy I truly appreciate you and your channel.. I am new to the boating thing, and have a lot to learn. thanks so much for your kindness and sharing your knowledge! John form sailing with mizz fitz

[@Cameron-ur2tk]

99.9% chance your boat is made using polyester or vinylester resin. There will be zero issues adhering to it, If there were already fixes done in epoxy on your rudder you may want to use epoxy. Step 1 Grind/ cut out any bad glass that is cracked, broken, and or delaminated from your rudder. Grind / sand edges where glass is going to overlap so you have nice fresh (paint free) surface for the new glass to adhere too. Once glassing and faring is done, you can either use an epoxy barrier coat to prevent osmosis then regular ablative paint, or just use ablative over the fresh repair. If your boat comes in and out of the water often there are numerous bottom paints like modified ablatives that are better suited. Talk with your local boat yard for opinions avout paint. 1 thing to note, epoxy work time can be much longer than polyester, easier for beginners to get a good layup. Poly can kick extremely fast if your not careful, dont work in the sun but rather the shade, if the repair area is large, layup 1 layer at a time, You dont want to be half way done with your glass layup and have it kick.

[@moviezaftermidnight6348]

You can use a light touch with a blowtorch to get rid of some air bubbles...

[@kylekragenbring1932]

Great info. How about with chop strand from a gun? I don't believe it would have any PE binder. Can you confirm?

[@mfournier12]

Depends on which CSM you use or which epoxy resin you use. You can use powder bonded CSM a which is compatible with expoxy west systems epoxy. The key is not use a CSM that is bonded together with a binder that requires a solvent poly resins have a solvent that breaks down the binder in CSM and allows a bond of the individual fibers when you wet up. BUT MOST epoxy resins do not. Powder bonded CSM (will be label as compatible with epoxy resin). Is a Mechanical bond that breaks down as you roll it in to the epoxy resin and will bond just fine. Works well in a layup alternating CSM and woven mat in the layup.

[@kevinmorris9712]

Why not just do all layers of 1708 in different angles?

[@rockcg22]

Thanks for the video. I learned tons. Question... I have a truck bed camper shell. The interior is that random chopped fiberglass. It looks like it may have been lightly painted white by the manufacturer., can't quite tell. As expected it has any number of glass threads sticking out. What should I use to seal that all in? Paint (if so what kind), resin (if so what kind). Thanks for your time. ~ Mike

[@soundsnvisions]

I really enjoy these videos. I do have a question: Do you have a video on how you gauge how much resin you will use on a project? It seems you nail the quantity pretty close in the videos I've watched. Unless.... You are ALSO a great video editor!! :) Keep up the great work. Not sure if we're sharing with you our latest snow storm down here in Eau Claire.

[@robertcain3426]

The ratio of resin to glass is 2/1 for chop strand layup. You can work it out yourself using maths.

[@robmill54]

Terrific information, can 1708 be used with epoxy? Thanks!

[@chroniclesofstuntbucket3522]

I need to repair a 15 inch gash on the bottom edge of a modern sunfish. How do I know whether to use polyester or epoxy to get the best adhesion to whatever my sunfish is made of? Does it matter? I think it is a medium stress area, not high structural stress because it is a curved edge. Am I correct that GelCoat is polyester?

[@TheDecguy]

That answers a few questions all in one episode.

[@limeyfynn]

So can you get the powdered csm in usa. ? Thanks, great channel. 😊

[@melissawey2104]

Thank you. This video answered some questions I was having 👍

[@ThatOldMan2112]

In the U.S. it doesn't work that well. But in Europe and Australia the CSM is powder bound rather than emulsion bound. The powder bound is compatible with epoxy - it comes apart just like the emulsion bound does with styrene. I don't know why they don't sell it here in the U.S., but I've been searching for a U.S. supplier for a month and can't find one.

[@kevinmorris9712]

US Composites

[@slawosze]

Hi, I really enjoy your videos. In UK you can buy CSM with different binder, for both types of resin.

[@sailinglaststraw5123]

Thanks for all the great info! I am not sure if the chop strand I get up here has styrene binder, packaging says for use with poly or epoxy? I have used both and like you showed it wets out best with poly. I just find the epoxy nicer to work with in terms of smell and also that it is a bit more predictable to manage as far as set up. 1/3 the price for poly needs mentioning too, especially if you end up with more epoxy resin wasted to fill the glass.

[@sailingbrewer]

Have you ever sprayed the csm once its in place ith acetone or some other solvent to dissolve the styrene? As a diyer I don't want to keep two glues on hand

[@JS-rp7qb]

Two glues isnt a bad way to do it. I recently epoxied the outside and deck of a flats skiff (Captive 14) and poly-ed the interior. The quick cure time of poly is a HUGE time saver and you still get the epoxy benefits on the outer hull.

[@larrybrevelle]

Can you try a small amount of acetone in the epoxy to slightly thin it. I find that the acetone breaks the styrene down allowing the epoxy to penetrate easier. Just a thought. Thanks for the video.

[@SPCSummer]

Thank you for the demonstration!

[@mboyer68]

I counted almost 40 separate movements with the steel roller on the poly going in both x and y directions. Maybe 12 fin roller motions with the epoxy, making it almost seem like....?

[@nickg7205]

What about adding some styrene to the epoxy (it'll happen to act as a thinner also) to help break down the styrene-based binder on the fiberglass fibers?

[@peterthomas1670]

Hi, I'm putting in a new ply floor in my boat, I want to go up the inside by 100mm up the sides an transom once prept, is it OK to use polyester over epoxy . Cheers Pete