How to Make A Fiberglass Mold from a Plug - Part 2

Knowing how to make a mold from a plug is handy for so many projects. Stephan is making a seat for his motorcycle but his technique can be used to make just about anything.
Follow along in Part 2 of this series as he coats the shape with TotalBoat 5:1 Epoxy and fiberglass. Stephan gives some great tips for fitting the fiberglass to the plug and for glassing the plug, too.

[@sarahpritchard3954]

when you finish shaping the foam plug to perfection ,spray a couple of coats of exterior acrylic paint on the plug and leave well to dry . Doing this will allow normal filler to be applied with no reaction ! make sure the exterior paint tin says "ALKYD'

[@handyallaround5776]

yes, great idea,,,,,,as far as polyester, you can spray pva mold release on the foam and it will not melt, be sure to let pva dry really well

[@the10thleper]

bent rodguy I didn't know PVA would protect foam from polyester resin. Nice. I have plenty of PVA. I had to cover my foam with bake potato aluminum foil sheets, using Elmer s glue to tack it down. It's easy to make a mess so be careful. I will have to try the PVA. Thanks I didn't know epoxy wouldn't melt the foam either. To expensive but nice to know for smaller projects.

[@giovannijoseph9580]

@@the10thleper , LOL! LOL, LOL

[@pangrac1]

Another mistake, learn from surfboard shapers. If you make perfect shape you will get perfect glassing. Mix some epoxy with microballs and fill all the holes and imperfections and sand them clean.

[@GaryL3803]

I would coat the foam with a thinned bonding epoxy to seal it and use polyester resin with fiberglass mat. Much cheaper for larger plugs and the mat can be shaped around compound curves, especially concave curves, much better than cloth. If you use epoxy over mat you must use unsized mat since the epoxy will not wet out sized mat properly. There is the problem with VOCs from polyester so you would need to use a respirator.

[@MrChris9830]

Try mixing cabo sil with the resin before adding your hardner, that will make a paste you can use for your hard to lay surfaces and get rid of your airbubbles(don't forget to add hardner to your paste) also you a lighter weight glass for your first layup, it will help with the air bubbles.

[@DIYAudioGuy]

You make it look easy.

[@internetttroll1908]

I would recommend you tape the plug/foam before you put the resin on it. thi sway, if you screw it up, you still have the foam intact. nice job :)

[@tommyt9519]

Use lightweight spackle to fill the low spots. Sands very easily.

[@aztecwarrior6284]

great informnation. learned a lot!

[@d.c7464]

You can you plaster-pairs to coat the foam when using polyester or other foam eating resins.

[@htpservices1863]

Is this the same process for carbon fiber. I like the foam idea and want to use it for CF projects

[@farookm.m.4208]

HTP Services I ' m going to mark hose door

[@markhamze154]

I coat the foam with five coats of house paint. Then I can use cheap risen and chop mesh.

[@An_Urban_monk]

Any particulars on the sanding method? e.g. did you use plain old sheets of sandpaper and if so what grit(s)? Power sander? Foam sanding blocks?

[@tommyt9519]

Use crowsfoot weave cloth instead of plain weave for compound surfaces.

[@MartinMasakowski]

I guess I don’t understand. What’s the point of making a fiberglass plug vs just a bare foam plug? It’s easy to shape the foam at get it perfect. couldn’t you then paint it with epoxy primer (545 as in his next video), finish fairing if needed, then buff and wax the primer for a gel coat that will be the mold? Seems like a lot of work to get a perfect shape and then fiberglass it and then reshape it.. thoughts? Am I missing something?

[@jacobkoshy9018]

How did you not burn the foam with the resin when it starts to cook???

[@readyxxi]

that was great

[@shivamtractors6003]

This sheet material?

[@mirceaandreighinea]

did you use the fiberglass scraps you show/talk about in the beginning (at 1:00)? if so where did you placed it? thank you! great videos you have ;-)

[@sand2698]

What material is that you hold with shape?

[@TheDcrocks1]

Why not csm as the base? Preference? ( chopped strand matting)

[@divyanshbhatnagar8784]

wht type of fiber you are using in this video pls tell me......................

[@davidhefner5668]

I would like to try this method to make a fishing kayak. I always thought this stuff would melt when in contact with resin. Oh.....your using epoxy....not cost effective. Anyway....what about some sort of barrier material. Kitchen plastic wrap maybe? A thin layer of troweled plaster? There has got to be something.

[@TotalBoat]

TotalBoat epoxy is cost effective! Check it out! www.jamestowndistributors.com/userportal/show_product.do?pid=64343

[@6h471]

Paint the plug with Elmers carpenters glue. Then you can use polyester resin and it won't melt the foam. I used this method many times. No need for pink foam either, I use plain old white bead board.

[@PushparajAmeen]

Any technical name for resin ?

[@ben_tang]

So could use this for gunwals on the boat?

[@M3_86]

Did you use the scraps too?

[@DarienCharlton]

Will using an orbital sander be too much to shape it or is using sand paper by hand a better option?

[@Gichanasa]

Surform blades are quite effective on foam. Orbital sander mostly melts the foam.

[@GasserGlass]

should be using chopped mat, not cloth

[@MrChris9830]

GasserGlass not for his first layer

[@GasserGlass]

FIRST LAYER FOR ANY MOLD OR PART should be chopped mat to insure no Print Thru!!!!!!!!! .... Its the FIRST RULE in fiberglass!

[@rickworthington3062]

even with epoxy? I believe hes making a part from the male mold and not a mold so would that perspective apply in that scenario?

[@kirkmartin2223]

Hes making a plug...not a mold. That plug will have multiple layers of glass added to it. Then fairing compound of some sort.... then some type of seal coat of epoxy primer or similar.......then wax....then PVA..........and then he will have a PLUG in which he will use to make a MOLD.... then he will build the actual final part. But if he was using a mold the 4th layer of laminate should be CSM with wax and PVA and resin or gelcoat coming before it.

[@danialasyraf2439]

Hi thank you for the useful tips , can i know what are the epoxy material and fabric cloth for making the fibreglass .

[@danialasyraf2439]

And what kind of epoxy should i buy ?

[@peterpham1782]

What methods did you use to shave the foam so perfectly round right after you cut the generic shape? I'd assume the foam is too soft to sand?

[@dejayrezme8617]

It's rigid foam, not soft. Afaik you can cut or sand it even with other foam pieces.

[@CAR-AUDIO-PRO]

What did you do to keep fiberglass resin from melting the foam?

[@tikitime]

He used epoxy instead of polyester resin. Epoxy does not attack foam.

[@swarovski333]

part 3 ??

[@ChristianRB89]

How is the epoxy not eating the foam?

[@Uberaroundtheworld530]

ChristianRB it’s not polyester it’s epoxy

[@chrisstanford3652]

🤗🤗

[@TotalBoat]

😎

[@ramongarciano569]

didnt mention anything about gel time or working time

[@devilrocks1406]

how much time will the epoxy take to cure??

[@steliosasmargianakis5188]

it depends the hardener. There are fast and slow hardeners.

[@onjofilms]

how you gonna get that foam out now.

[@tenders]

That's a "plug," a male mold. He doesn't need to get the foam out.

[@onjofilms]

Oh.

[@Gichanasa]

Use a combination of the hot knife and the heat gun.

[@giovannijoseph9580]

...but...why wouldn't he pull out? I mean, when he's done, she's done, right? So pull out; and do again, and again... and agin...! Right? Who would want all that weight, from a HARD mold added to their cafè racer? That's a cafè style seat part - where the seat fits! He did not make a filler, as mentioned, to fill in low spots, and did not spray on mold wax, as mentioned; so, he'll have to pull the walls of the part wide, then pry like hell! 50 to one, it will break, first try? 100 to 1 it will break in any number of tries? - tries, to pull the foam core out... unless he put mold release wax on it, off camera...? JK, not a beating fool! By the way, that's why the mold is several layers of rigid foam board. It's easy to cut and sand, then each section pulls out from the center, easily - once the bottom is pulled/cut off, holding it together. The outer slices then are easier to take out. BUT, whea du wax? LOL ;^D Giovanni Joseph

[@robertcain3426]

@@giovannijoseph9580 Giovanni, I think you're a little confused. He's making a plug, not a mould. He'll make the mould off this plug.

[@rcstuff7718]

I tried doing it on a foam mold like the guy in the video did but my foam just started melting right away when I put the resin on and all of my hard work of carving the foam just disappeared

[@tenders]

He mentioned this. Polyester resin dissolves foam, epoxy resin does not.

[@kirkmartin2223]

@@tenders epoxy resin CAN melt pink panther foam. I've melted it using epoxy resin in the shade when it was 95° outside. It was my mistake and had the air temp not been so hot it wouldn't have happened I think

[@dooo679]

guarantee i would end up with 5 times as much hardener as i needed. 5 to one is 5 pumps to 1 pump

[@dooo679]

er 1/5 as much see i messed it up wit yer crazy pump system

[@TotalBoat]

our crazy EASY Pump system!!! If you can read (the directions included!) then you can do it! 1 pump to 1 pump. Delivering the right mixture every time!

[@tenders]

Everybody makes that mistake, but only once. Without the pumps, you have the opportunity to make that mistake on every batch.

[@chandrabhanprasad6882]

Mai v to bannata.hoo

[@elmonociclista]

what grit is recommended for sanding this?

[@giovannijoseph9580]

If it's really a bumpy mess like his will be, start with an angle grinder, 80 grit, then 120, 240, then wet sand with 400, 600, 1000, 1500, 2000, 3000, and finally buffing, with 4000 or 4500. It can be hard to find. I would put your gel coat on when tacky, after water washing the wax produced from drying, then increase the wet emory cloth each layer, and clear coat layer, with a final buff! Ooop, no clear coat, for non-composite non-gel-coat parts! Apologies... also depends on, if you will be walking on it - decking. It will need a bit of roughness, so you don't slip into the ocean, and get sucked into the abyss, disappear, and drown! With a female mold, you can super fine sand the mold, and start with wax, then gel coat, and layup glass. It pulls pull ready to de-wax, and use - usually. LOL DOH! What?

[@TheModryperak]

super

[@nicholasvangreat260]

Only one layer of glass and then faring? Well, that was a waste of a plug and a project.

[@combojerman28]

DAMN! TERRIBLE SYMMETRY DUDE!