Advice on fiberglass molding

[Greg Johnson]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?

Thanks,

Greg

 

[SayMikey]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?
Thanks,

Greg

I assume your using epoxy. Taking your time works best. Also if the bubbles apear at the edges try some ground glass in that area. I lay up parts using a small brush. I use mostly west 105-206 slow set helps also a good prep with wax and pva to release. Practice and patience along with a good look at the finished part and trying new things to cure problem areas..............

 

[Greg Johnson]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?
Thanks,

Greg

I assume your using epoxy. Taking your time works best. Also if the bubbles apear at the edges try some ground glass in that area. I lay up parts using a small brush. I use mostly west 105-206 slow set helps also a good prep with wax and pva to release. Practice and patience along with a good look at the finished part and trying new things to cure problem areas..............

Yes, I'm using West System 105 with 205 hardner. I've been brushing the epoxy on the mold then laying in the cloth dry then pouring in additional epoxy and brushing it into the cloth.

I'm not pleased with the interior surface as it is not at all smooth doing it this way. I see other parts molded in fiberglass and they have a smooth surface on both sides of the part. Not sure I'm using the correct technique???

 

[TERMINATOR]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?
Thanks,

Greg

I assume your using epoxy. Taking your time works best. Also if the bubbles apear at the edges try some ground glass in that area. I lay up parts using a small brush. I use mostly west 105-206 slow set helps also a good prep with wax and pva to release. Practice and patience along with a good look at the finished part and trying new things to cure problem areas..............

Yes, I'm using West System 105 with 205 hardner. I've been brushing the epoxy on the mold then laying in the cloth dry then pouring in additional epoxy and brushing it into the cloth.

I'm not pleased with the interior surface as it is not at all smooth doing it this way. I see other parts molded in fiberglass and they have a smooth surface on both sides of the part. Not sure I'm using the correct technique???

alot of guys use a vaccum bagging technique. i use lead shot and a layer of saran wrap.. it make a nice finish on the inside and makes a smooth outside as well, and kills the little airbubbles too. and it is addicting too, i find i make molds all the time. it is fun

terry

 

[Mark Poole ModVP]

Greg,

Are you brushing in a coat of Epoxy, letting that dry (as a skin) and then laying up the cloth? Laying in the cloth without a dried skin coat will result in many surface imperfections.

Also, instead of laying the cloth in and then pouring resin over it, try bushing in a nice wet coat of resin then laying the glass in. Wets out faster this way with less dry areas.

 

[Mike Hughes]

What size cloth are you using for your first layer? 6oz. does not work as well as a 2oz. It tends to draw up the epoxy into the cloth and you gety bubbles. I use the 2 oz and then 2 layers of 6oz for most of my applications.

Mike

 

[SCOTT WITHERELL]

EXP,:when I make a cowl)just an Idea I came up with? ,I spray PVA and let dry really well, then I do 2 layers of 20 min epoxy, the 2cd layer I put on 1/2 hr after the 1st layer gels up. then I use 1hr epoxy for the 3rd coat ,1/2 hr after the 2cd coat has gelled up and then I put on the 3rd coat and wet it all out. then I put on the cloth 2 layers back to back. then it's time to vacuum the cowl while the 1hr is still wet,I use low temperature release film,then breather bleader materal, on top of the cloth,Now the fun part, Seeing that my cowl is 4inch wide and 27 inch long I use a food saver bags and bagging machine to vacuum the cowls down. (works great)some places for infomation. www.fibreglast.com ,I use there stuff ,

 

[SayMikey]

EXP,:when I make a cowl)just an Idea I came up with? ,I spray PVA and let dry really well, then I do 2 layers of 20 min epoxy, the 2cd layer I put on 1/2 hr after the 1st layer gels up. then I use 1hr epoxy for the 3rd coat ,1/2 hr after the 2cd coat has gelled up and then I put on the 3rd coat and wet it all out. then I put on the cloth 2 layers back to back. then it's time to vacuum the cowl while the 1hr is still wet,I use low temperature release film,then breather bleader materal, on top of the cloth,Now the fun part, Seeing that my cowl is 4inch wide and 27 inch long I use a food saver bags and bagging machine to vacuum the cowls down. (works great)some places for infomation. www.fibreglast.com ,I use there stuff ,

205 flashes off too fast you need 206 for a better finished product

 

[Terry Keeley]

EXP,:when I make a cowl)just an Idea I came up with? ,I spray PVA and let dry really well, then I do 2 layers of 20 min epoxy, the 2cd layer I put on 1/2 hr after the 1st layer gels up. then I use 1hr epoxy for the 3rd coat ,1/2 hr after the 2cd coat has gelled up and then I put on the 3rd coat and wet it all out. then I put on the cloth 2 layers back to back. then it's time to vacuum the cowl while the 1hr is still wet,I use low temperature release film,then breather bleader materal, on top of the cloth,Now the fun part, Seeing that my cowl is 4inch wide and 27 inch long I use a food saver bags and bagging machine to vacuum the cowls down. (works great)some places for infomation. www.fibreglast.com ,I use there stuff ,

That's kewl using a Foodsaver, boater's gotta be the most inventive modellers on the planet!

 

[Terry Keeley]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?
Thanks,

Greg

I assume your using epoxy. Taking your time works best. Also if the bubbles apear at the edges try some ground glass in that area. I lay up parts using a small brush. I use mostly west 105-206 slow set helps also a good prep with wax and pva to release. Practice and patience along with a good look at the finished part and trying new things to cure problem areas..............

Yes, I'm using West System 105 with 205 hardner. I've been brushing the epoxy on the mold then laying in the cloth dry then pouring in additional epoxy and brushing it into the cloth.

I'm not pleased with the interior surface as it is not at all smooth doing it this way. I see other parts molded in fiberglass and they have a smooth surface on both sides of the part. Not sure I'm using the correct technique???

To get both really smooth I think you need a 2 part mold and squeeze them together, but why? :huh:

 

[MEAN GREEN]

EXP,:when I make a cowl)just an Idea I came up with? ,I spray PVA and let dry really well, then I do 2 layers of 20 min epoxy, the 2cd layer I put on 1/2 hr after the 1st layer gels up. then I use 1hr epoxy for the 3rd coat ,1/2 hr after the 2cd coat has gelled up and then I put on the 3rd coat and wet it all out. then I put on the cloth 2 layers back to back. then it's time to vacuum the cowl while the 1hr is still wet,I use low temperature release film,then breather bleader materal, on top of the cloth,Now the fun part, Seeing that my cowl is 4inch wide and 27 inch long I use a food saver bags and bagging machine to vacuum the cowls down. (works great)some places for infomation. www.fibreglast.com ,I use there stuff ,

That's kewl using a Foodsaver, boater's gotta be the most inventive modellers on the planet!

every boater knows that we are the sickest people out there we are the only ones that take house hold items and use them for fun :lol: :lol: :lol:

 

[Greg Johnson]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?
Thanks,

Greg

I assume your using epoxy. Taking your time works best. Also if the bubbles apear at the edges try some ground glass in that area. I lay up parts using a small brush. I use mostly west 105-206 slow set helps also a good prep with wax and pva to release. Practice and patience along with a good look at the finished part and trying new things to cure problem areas..............

Yes, I'm using West System 105 with 205 hardner. I've been brushing the epoxy on the mold then laying in the cloth dry then pouring in additional epoxy and brushing it into the cloth.

I'm not pleased with the interior surface as it is not at all smooth doing it this way. I see other parts molded in fiberglass and they have a smooth surface on both sides of the part. Not sure I'm using the correct technique???

To get both really smooth I think you need a 2 part mold and squeeze them together, but why? :huh:

 

[Greg Johnson]

I'm looking for some pointers on eliminating the small bubbles in the surface of parts when hand laying them up in a fiberglass mold. Is vacuum bagging the way to eliminate these imperfections?
Thanks,

Greg

I assume your using epoxy. Taking your time works best. Also if the bubbles apear at the edges try some ground glass in that area. I lay up parts using a small brush. I use mostly west 105-206 slow set helps also a good prep with wax and pva to release. Practice and patience along with a good look at the finished part and trying new things to cure problem areas..............

Yes, I'm using West System 105 with 205 hardner. I've been brushing the epoxy on the mold then laying in the cloth dry then pouring in additional epoxy and brushing it into the cloth.

I'm not pleased with the interior surface as it is not at all smooth doing it this way. I see other parts molded in fiberglass and they have a smooth surface on both sides of the part. Not sure I'm using the correct technique???

To get both really smooth I think you need a 2 part mold and squeeze them together, but why? :huh:

Terry,

It's just that the inside is so lumpy that it make a poor surface for mounting. I'm making a tunnel cowl and it's just too lumpy. I don't need a finished surface just something better than I'm doing now.

There have been some great suggestions that I will try.

Thanks to all that have helped me out.

Greg