Final layer of mold plug?

OK guys I am back, working on another plug since the previous one worked well. I ended up making a second mold so can sandwich the two molds to make the part I need. Making that plug was easy because it was pretty much a flat piece...now I am working on another plug that is more complex and having more questions

So I used blue form and spakle to shape the plug, I put two thin layers of EPOXY fiberglass over it to stiffen it. (darkened the resin for a uniform color) The problem is: the fiberglass weave is showing through the epoxy over pretty much the whole piece.

What should be my next step to smooth it out and get this puppy ready for tooling gel coat??? Obviously sanding but I dont think I can get a perfectly smooth finish.

 

fairing compound ... epoxy, microballoons and some cabosil then sand that down to perfectly smooth. ... what did you tint or paint with? Not sure if you can fair over that. Might have to use high build sanding primer

 

Never worked with fairing compound, is it easy to use and sand?

I tinted the epoxy with pigment drops I bought from fiberglasssupplydepot.com

I have used sanding primer before but the tooling gell rips it off

 

Fairing is a pain when your doing an entire boat but for a little part like that it's a breeze and yes very easy to sand. Mix 4 parts microballoons to about one part cabosil. The cabosil makes it hard so when you sand it doesn't clog the paper. Add that to epoxy till you get your desired consistency. Fill the weave and then sand away. You often have to do more than one coat, just wash it down and recoat. Since you tinted the epoxy I am pretty sure you can fair right over it. EDIT .. Start with about 120 Grit, you can go all the way to 320 and get it glassy smooth.

 

Should I buy an epoxy compound or make my own? I already have the 403 404 405 west system, just not the cabosil

Yes what I am worried about is how to get the whole like look like a mirror and be shiny. If areas are really rough now if I eventually work up to 1000-1500 wet, will the epoxy get very smooth?

 

So I looked at the filler chart and I notice 407 and 410 are the FAIRING FILLERS, I tried a quick sample of 403 and it didn't fair out easily (based on the chart you cannot use an adhesive filler to fair).

I did spread some of the thickened 403 around the piece and wiped it off with a towel. It made the piece somewhat shiny and filled in the mini scratches. I think I am getting somewhere. I just ordered the 410 and will give that a try.

 

West 410 is an easy sanding filler aditive, makes a very smooth and creamy mix that comes off a broadknife well.
Pretty sure it wont buff to a shine though, once sanded very "chalky" in surface texture, I've always thought of it as very expensive, I will use it for some fine screed at the end of a fairing job but do the bulk work with Q cells.

What I'm seeing on your current job there is very much like surfboard work,,, like glass... fill caot... gloss coat(maybe one step too many), I would tend to give the fabric finish a quick sand all over & especially at the overlap to feather it then I would just brush on 3-4 coats of epoxy with a wet on tack approach then when it's all nice and hard just work through the grits(wet sand) until it's silky smooth & hamonious all over, if you hit the fabric that's too far but will be ok... you might buff it a bit but epoxy gets soft with heat so just hand buff then some couple or few coats of pva compatible wax & shoot/spray or lay on some pva with a dampened scrap of foam, with pva the release agent is the finish.... so spray can be good, it's possible with multiple coats and patience(make a cup of tea & drink between hits) to build quite a "juicy" shiny coating, if you muff it just wash off & have another go..

Jeff

 

You've made things hard for yourself using epoxy, in polyester you could have used all the polyester based auto products, faster and cheaper, anyways from what i am seeing a high build primer would put a finish on that.

 

True,
in poly that could be ready on the first day.
Jeff.

 

So I used the 410 and it makes the epoxy similar to thined gel coat, very easy to work with. I ended up foam brushing a thin layer on but now I see what a fair is. Gravity makes it smooth and even WITHOUT DRIPPING. Wish I knew about this stuff sooner. I think I can shine it up pretty good with sandpaper- but you are right, the PVA is going to give it the best shine

I have to do things a little bit differently because I don't have spray equipment and the weather is getting very cool right now...the only option I have is to use the basement...would prefer to stink up the house the few nights I use the tooling gelcoat only, not during the several weeks it takes to build the plug

I have trouble using epoxy on a piece like this because if I dont add the 410 is drips all over. I'll let you know how the 410 works went sanding...

 

So, since you were just filling the weave that probably worked okay, you will find out when you start sanding. Fairing compound usually doesn't run, it's more like drywall joint compound, it's supposed to fill low spots and not level out on it's own.

Then you would sand with a long board or in your case a short flexible one to get it fair. I think it will work what you did though.

 

I feel to fill the weave and with all the curves I had to make the fairing compound somewhat thin. Seemed like it worked well, but we will see when I start sanding. If it was any thicker it would have been tough to get around all the curves. I can see how thicker mix would work on a flat surface

 

A place I worked at used the 410 in a sloppyish mix as a "flow bog" for cabin tops and decks to small launches(over dynel), seemed to work pretty well with an easy sanding "crust" on top & a higher density left behind, was applied with a broadknife & was semi self leveling, once cured a RO sander or planetary sander made short work of smoothing out in prep for paint.

Jeff.

 

The 410 mix sanded excellent. This is the exact product I have been looking for for a while. It's amazing to me that even after waiting 24 hours to sand- the paper does not get gummy at all. It's very easy to sand!!

It dries shiny and extremely hard so after I fill all the gaps I might brush on a very light coat and start sanding with 1000 after it dries. That will give me a head start to possibly 2000 grit and then it is ready to pull a mold off

 

So I tinted the epoxy black (dark gray), mixed hardener and added the 410 after. It is very easy to brush on with foam brush but can set up quick enough on you if you don't work fast.

I coated the whole outside with a thin layer which didn't drip or run and faired out flat. Overall very smooth and shiny but there were some rough areas, areas of roughness. This being the second coat helped- first coat was sanded to 150....I waited two days and sanded with 1000 wet. The whole piece is mold worthy already after a light sanding. Once I wax and put on the PVA it's going to be a great setup

No I just have to fill the 3 small pin holes left over