ahoy matey .. first fiberglass plug and i have a concern

hi .. i be yer first mate leroy in tennesse

i'm new to the forum and new to composites .. and as i keep searching relevant forums for info yours keeps coming up .. so ther must be some smart skippers here ..

i am also into boats .. i'm nearly finished with my 59' lone star restoration .. a 15+ fiberglass runabout .. though i'm here about another question ..

i have designed a plug for an auto part .. i am a body / paint guy .. so that's to be expected .. i used what materials i have laying around the shop .. welded some steel .. spread some 'bondo' .. glaze .. 2k .. then topped off with black ppg mtk acrylic urethane ..

and now i'm researching how to transform this here plug into a mold .. and i'm quiet alarmed at a post i found where a feller says auto paint is a big no no when it comes to making a plug !!? what the heck ?

something about styrene reacting and acting as a solvent to the paint ..

isn't pva provide a sufficient barrier ?

i don't want to lose these plugs i've worked hard on them for months and they're perfect ..

another forum i found someone says he paterns parts on auto parts painted with urethane no problem?

be there truth to the tale that me plug be doomed to davey jones' locker?

can i seal it somehow if so ? what about a spray down with shellac prior to waxing ? maybe this seals it ? someone mentioned a product called crystal clear .. is this a sealer and would it keep a dangerous reaction from occuring ?

what if i just scuffed it and hit it with a topcoat of 2k primer ? would this be more likely to succeed ?

what if i layer up 10 coats of pva? likely to provide adequate barrier protection ?

maybe it's nothing at all .. maybe it's a disaster .. what be your thinking on the subject master mold makers ? what do i do ? or should i wax up .. pva up and stop worrying ?

i don't wanna end up shipwrecked !!

 

Do a test panel. I've made a large plug with bondo over fiberglass and then primed and then one coat regular 1 part auto enamel. After 4 or 5 coats of wax and one of pva, the mold (2 part split mold) came off with no problem. That was with polyester resin.

I've never used any 2 part stuff, or urethanes, maybe someone else can comment on that.

Try a test panel, using the same paint, something rounded a little and not just a flat surface. Maybe use a couple square feet of the side of a metal barrel and include some of that small ridge they have .

I assume you know about "draft" and not making a mold that is unremovable from the plug because of the shape...?

 

I have sprayed plugs with linear polyurethane, and it worked fine. Probably your best bet is to call the paint manufacturer and ask what the paint is chemically resistant to.

 

thanks for the replies Sam & Gonzo ..

that is a bit reassuring that you've done it before with no prob over auto enamel ..

i generally consiter mtk urethane tough stuff that flows even and easy that's why i use it as my go to ss paint ..

when i read on the internet 'paint problem' it could be real .. but there's 1,000 kinds of automotive paint .. and i can't be sure the guy that had the prob even catalized and thined it correctly in the first place ..

i'm headed out to grab the last things for layup .. johnsons paste wax .. and formica ..

gonna do final sanding and setup the flange for gelcoat application and layup tomorow mornin'

i think (i hope) it'll be okay .. not gonna call em' because if it acts as a paint stripper anyway i'm screwed and then the stripped paint would just give me a head start on stripping it all off anyway .. i really really really hope this works!

just gonna spray plenty of pva and attempt to seal all edge voids with play doh and leave a wet wipe of wax over the edge and use a lot of pva .. this .. in my hopes will keep the two apart .. i hope ..

it might not be a prob even .. i do have some oversprayed wooden planks that i had layed the pieces on when i painted them .. so i will do a test for reactivity .. with pva & without pva to the gelcoat to see ..

thanks guys i know it's one of those questions that's hard to say about unknown material and i appreciate your replies ..

ohh also yep the draft is appropriate .. the parts were difficult to design with the draft thats why i'm so concerned about bungling the mold on some reaction .. there's some leeway .. but they're still not straight pieces and i don't wanna stick ..

i will update ..

 

I have used car paint many times and the only times I had problems were when it hadn't had time for the solvents to disperse.If you give it a few days or bake it to complete the cure,there should be no problem.PVA is a bit traditional these days there are alternatives which seal the surface and you can then use wax to guarantee a clean release.

 

ahhoy

thanks very much wet feet .. boy am i glad to hear that

it's cured i baked it in the hot sun and it's painted black .. so they got quite hot indeed ..

i have returned from my quest for wax and formica .. i got a bunch of FREE (rrr .. i am a pirate)samples and a for sale sign to cut up and reinforce with superglue to make plastic flanges ..

hehe .. the toughest part was finding a wet film thickness gauge .. i had to sail to 3 sherwin williams stores till i found er' .. TY SW!

i understand these are critical for proper application of tool gelcoat ..

question rrr // how many mills should i be laying down ?

i read several desc. stating 15-20 and some saying 20-25 mills and some outliers also .. what's the golden standard ?

also i have been reading all i can about gelcoat application .. most suggest spraying from between 1 to 2 feet away ? at 90 psi ? these peramiters are much different from paint .. where i spray 10 inches +-2 inches at the lowest psi i can achieve good atomization and pattern ..

so i opened up the can i have hear .. and indeed it be a much different animal .. it be no porpuse or whale .. she's a mermaid ?! very strange indeed .. so thick it looks the consistancy of between ketsup and mayonaise ..

it hadn't even flowed out in the can ! it still had chop and waves of a good swell ! what am i gonna do with that ? i can't imagine this will even flow through one of my guns ??!

i know everyone uses a dump gun for gel .. but i was thinking .. 'rrr i can do it .. i can wet some spray down on any poop deck' but rrr this looks like dangerous duty !

can this be thinned with acetone or lacquer thinner? i have read yes .. and no .. most say use duratech to thin it 30-50% .. though i have none at this moment ..

i was talking to a supplier about putting me in contact with another local jobber whom i can parle with on attaining small amounts of materials should the need arise .. and he put me in touch with another lad not far from me and they make ford truck accsessories also .. so that's great i will probably go there in the morning and hopefully he has some little bit of duratech he will sell me ..

how many gold coins should i offer for a pint of duratech ??

if he hasn't got some of this misterious duratech what sould my plan B be ?

i don't want to get a dump gun .. i be limited in both time and money ..

i understand in europe brushing gel is still the norm ? exactly what technique should i employ should i need to take this voyage ?

what is typical for kick time of gelcoat .. and what are the syptoms that it's almost time .. and from there how long till it becomes critical ..

for instance .. the bondo i use usually gets 3 minutes till it kicks .. it begins to pull and get some chunks .. i can finish the current wipe with more pressure .. and then i cannot apply even 1 more wipe .. it's done .. wipe off the spreader immediatly within 20 seconds on a dry paper towel .. trim off excess bondo on the piece or vehicle with a razor or knife immediatly before it fully hardens to save effort .. .. repeat

i read on a thread here .. one brush full .. six wipes back n forth .. dip brush again six wipes back n forth .. in one direction .. then a second coat after about 2hrs on a roller in the opposing direction .. that is probably entirely wrong so please if you know advise me on brushing gelcoat ..

sorry i'm writing alot ..

umm rrr

it seems like painting .. composite work is a dark art .. there is alot of under information .. mis information .. and imcomplete information out on the net ..

i know 98% of what i read on painting in not correct so i always keep that in mind and look for 100 articles and refrences to find the 2 that are accurate ..

here is .. seemingly the most complete instructions i could find on making the molds ..

http://www.sceadu.com/support_fiberglass.html

i printed up a copy on decent paper at office max rrr so i can refrence it while i work and not have to contaminate me laptop ..

the descriptions here seem to cover the main points well while sailing past the details .. i thought it was funny to see a rubber sanding block
but i definetly like the steel frame ..

he mentions not sanding out to 2k or super fine or the gel may lift off the plug in what he terms 'the dreaded pre-release'

so i'm glad i read this because i sure like to sand things all the way to 3k ..

where should i go to on the plug ? 1k .. 1,200 .. 1,500 ??

and then sand and buff the mold i suppose ..

also .. can i do this all outside ? my boy likes to run around barefoot like everywhere .. so i was thinking of taking a few tables and chairs out to a remote corner of the woods here where he's not gonna trample .. setting a few fans on me and doing it outdoors .. is this a problem with sunlight ? dust ? or bugs .. if i get a bug just tweezer it out while whet rite ?

i can do it in a little old crummy office space indoors if i have too because jackson wont be walking in there ... eventually i'm gonna staple plastic up in there and make it my little production area anyway eventually .. then get a shed or build a little lean to eventually .. just wondering for now can/should i work outside?

again i appologize for the long post and going on and on ..

what's a good technique for waxing ?.. should i let it haze up 3-5 minutes before buffing out or just run it out wet ..

what rags should i use for application and rubbing out ? i read many places to use microfibre towel because they won't scratch like a cotton rag will ..but in the ^^^ article he says to use cotton rags ?? what sayy ye ?

i have a breathable tyvec suit .. saftey glasses ... respirator gloves .. .

he ^^ made his mold 12 layers thick .. i read else where alot of different suggestions for thickness the guy at the fiberglass supplier said only 3 layers to 4.5 oz total .. though i don't know that he understands that i am serious and intend to make a real production mold to pull hundreds of parts from ..
what's a good thickness and what benifets be got from a nice thick 12 layer mold ? strength .. straighness .. longevity?

there are 5+ ways it seems to do everything .. and that's why i'm asking advice from the pros before i get in deep and rough ..

what is he missing .. or doing wrong .. or can be improved upon in from the feller is doing in step by step ..

also i made up a catalyst chart for my use while working so i wouldn't have to stop and make out figures .. pleas confirm my calculations are appropriate ..

i understand standard mekp ratio for tool gel / resin is 1.5 percent .. correct ?

i found a resource that says 4 oz resin (9.2lb) gets 1/16 oz cat ..
so .. 1oz being 28.35g that would get .443g for a weightout of 28.79g on my mini scale correct?

i extrapolated this out for each ounce out to 12 for easy measuring ..

so 9oz resin or gelcoat on the scale should read 255.15 then i weigh up to 259.137 for a catalyst of 3.99g

sorry again for going ON and ON .. this is probably the longest post in history ..

but the real quest is getting inside of the chest .. unsheathen your weapons to find gold coins n gleaming jewels ..

if your not tired of reading my question s maybe you can help me plunder my booty by answering me this riddle ..

the composite saler gave me some resin .. i think it's tooling resin but i don't know for sure .. the brand is polynt and it is 970g353c-qm pirogue green / material# 924071 ..

i don't know what this is any ideas ? it says "contains: DIETHYLENE GLYCOL, TITANIUM DIOXIDE" is that some hint as to it's purpose? maybe a blended poly resin or whatnot ?? i suppose it still kicks with mekp .. and i may have to call and ask them because i can't find any literature on it at all ..

if this stuff is some nice fancy tooling resin .. can i use it for the first layup and the next 2 or 3 layers .. then switch to the bondo resin to finish ? are most resins like this compatable ? would doing so be detrimental or defeat the purpose of using tooling resin ? reason i ask is that it's a 2.032 lb pail and i'm thinking it won't do all my plugs if i make them nice and thick ..


thank you for reading me long tale ..
please show me the map that i can quest fer the treasure ... rrr

 

A lot of this stuff has been covered here before. Scroll down to the bottom of the page to "Similar Threads" and you'll find links to other threads. On each link there will be more links at the bottom of the page.

 

I've done exactly what you're doing, many times. Built many plugs, molds, for motorcycle and auto parts. I coat the plugs with auto wax and leave it on fairly thick, then lay the glass over it and use an airhose to seperate them when cured. Then the same thing to build the part.

 

If you're going to make hundreds of parts from the mold, the plug should be finished to the same finish as you want on the finished part. You shouldn't need to do any more than a light buffing on the mold, after removing it from the plug. After de-molding the finished part/product, if you have to sand and/or even buff it to get it the way you want it, it is a repetitive waste of time.

 

thanks 4the replies Sam + Freddy

yep i see that much is discussed already in other threads .. i do search and read them ... ALOT of reading .. after reading what other people have said on much of this i'm now forming some ideas ..

nothing is worse than basing conclusions on mistaken ideas on the precept .. so that's why i'm kinda looking for maybe a 'proofread' of my concepts that i have drawn out to point out my mistakes .. because i'm 100% sure i'll make some if i don't ask ..

--
thanks i will wipe on a hefty coat of wax on there .. i have cut the orange peel off this morning .. just a bit left to do now ..

i don't sand off orange peel .. i use a razor perpendicular at 90* or behind and drag it over the surface back n' forth in long even strokes to cut off the high spots .. change razors as frequently as paper .. nothing worse than a dull razor .. this saves a tonne of time .. makes for literally 'razor sharp' flat paint and acually cuts less of the paint to get to the flat surface .. yes you can ruin a paint job if you don't practice but it's not hard .. and u never burn through like is possible with lower grit papers .. i go over every paint job first with a razor to cut peel then lightly wet sand out to finish 1200 1500 2k 3k and then compound with an egg crate foam bonnet then polish with a smooth bonnet .. just a tip from an auto body paint guy ..

after i get these finish sanded gonna glue the formica reinforce with glued paint sticks - play dough the seams .. and wax er' up good ..

will update .. rrr

^^ anyone please feel free to chime in on the questions queried in the 'giant' post .. thanks ..

 

the plugs be sanded rrr ..

they do look magnificent ..

i split the difference and polished the front visible pieces to a fine luster ..

and left the sides and non critical areas at 1,200 in hopes to acheive more grab .. and not have the gelcoat pull prematurely..

i red that thin gel aligator and thick will pull .. so i kept it a wee bit rougher with the idea in mind that if i do brush on the gel i can perhaps get away with a thicker application .. more closer to 25 mil .. as it would perhaps be difficult to hit it with precision on a brush .. and i don't wan't any gators er' crocks froating in these seas rrr ..

i'm starting to get excited with how these plugs look .. though i think perhaps me'd ben better off forming a large tapered hull to these little pieces .. they are going to make up an aftermarket automobile grille thats' why i ben working them to perfection .. any flaw is unacceptable ..

will update ..

 

Go slow in the layup. Don't over catalyze the resin and work in a moderate, regulated temperature. Apply the gelcoat and give it plenty of time to cure. Overnight is good. Then a resin rich layer of 3/4 ounce mat or veil, let that cure and cool down, then another. That's a day. Next a 1 1/2 oz layer, let it cure and cool down, then another. That's another day. Go slow and don't worry about pre-seperation. Use Isophthalic Polyester for the mold, http://www.fibreglast.com/product/Isophthalic_Polyester_Resin_just_resin_90/Polyester_Resins I just used it for everything, making the mold, parts, repair etc.

I've never had any luck brushing on gelcoat. You have to apply two layers then and the thin parts of the first always alligator, at least for me. Some people have no problem doing it. I always used a cheap cup/dump/slobber gun like this...

 

thanks 4 the tips ..

will take it slow as you suggest ..

i will get that resin in the future .. for now i have just what i have on hand ..

but the good news is .. i checked the pail of higher quality resin i have for weight and it's actually 4.5 lbs so a half gallon .. so i suppose i will make the molds with half that and half bondo resin ..

i know .. i know .. bondo brand sucks .. at least their filler .. so i'm sure the resin is also crap .. i still have the receipt and the jug is unopened ..

i may have to take it back and go get the real stuff ..

but at least i should be able to start it with real resin i have already

i'm going to avoid brushing at all costs unless i have no other choice ..

i picked up a el cheepo hvlp gun from horrible freight .. for spraying the pva ..

as i don't know if it would contaminate a paint gun .. so .. i was thinking about trying to push the gelcoat through that thin g .. if it won't flow at all .. i'll just break it down and clean it before it kicks .. and use it for pva only ..

my best choice will be to source some of this duratech .. i'm going to hunt it down if i can and shoot from a regular paint gun ..

brushing is the last option .. but not off the table .. i do really want to avoid the m gators though ..

..

rrr .. i made a discovery i thought i'd share .. it's pretty amazing actually .. perhaps this isn't new .. but i never heard of it before ..

using baking soda as a hardner for super glue !

instead of a 3 minute setup time it's instant .. i mean 3 seconds .. it gets hot too like 200*

how come i didn't know this !

also it fill voids whereas super glue just works by direct contact .. zero gap filling potential .. i was brushing baking soda into gaps between the plugs and formica and build up the gap with powder .. drop a drip of super glue every 1/8 inch and presto bamo .. stuff is done .. dry .. hard .. and now has real super strength .. like mechanical strenth propertyies ..

i sucsessfully bonded 3 seperate pieces of formica going different directions with high spring back pressure .. just butted up against each other .. no other glue could do this i don't think .. but i just sprinkled a dab of baking soda over the seams .. spread it flat with a razor and dropped super glue till wet out .. bam 5 seconds later .. done ! increadable .. i can use this stuff to easy fill 1/4 gaps now .. with great strength ..

if this is a new discovery i'm not gonna patent it .. but be it known .. it'll be named leroy glueing or pirate glue technique rrr

okay .. later .. i'm deleriously tired

will update ..

 

rrr .. an update

i got me flanges made up rite nice ..

an made some reel fine radius'd edges of play doh .. rrr

me boy took off with much of me material to play with ..

but it looks fine indeed .. i sealed the formica and doh edges .. so not to reopen it up with the also water based pva ..

waxed'r 10 times and sprayed pva ..

then had a minor disaster .. rrr .. we were making good wind with favorable seas when i decided to get creative and deviate off course ..

i used a 1/8 drill bit (3.1mm) to open the tip of that throw away harbor freight 'paint gun' btw it was a junker before i drilled'r out .. it barely made it through pva application .. and the needle was rough and not smooth .. the air continued 1/2 second after trigger release !/? well it was just a junker .. that 's why i didn't mind experimenting with a drill bit to see if i could push out some o' this gel .. rrr

nah it don't work .. i mixed up a cup of gel and watched as it bubbled in the cup .. never made it into the needle and transfer area .. the 1/3 inch hole in the bottom of the cup was the restriction !! like ice cream rr.

so .. i grabbed a brush and layed down a few strokes on some junk wood ... just to see how it be .. and left some in a mixing cup and put some at varying thicknesses on things .. just to get a feel of what it does and how it handles varying thicknesses .. porosity .. cracking .. gatoring .. ect .. at that point it was not going to happen so why waste the goop when i could do some experimenting ..

i cleaned the gun out in time .. and it's going back to harbor freight where i hope they send it back to china where it belongs.. ohh btw .. the hole i drilled worked .. and it sealed rite ... so just so you fyi .. you can drill out a cheap hf gun to push some thicker material .. say perhaps some filler primer out to 3mm .. so if you have some thick job that you need a 1x gun for maybe that'll do it .. just not this thick .. i think this gelcoat stuff needs a HUGE passageway to make it by ..

anyyway .. so i put up the gun .. and it started raining :/ and pva is water soluble .. so i had to wipe it all off and gonna start again with a fresh coat of pva tomorow AM .. then gonna try me luck at finding a pro with a cup gun somewhere nearby if a can or get some duratech .. and last but not least if all else fails then it'll be the brush rrr..

fortunately the stuff seamed to stay pretty well in shape where i brushed it and in the cup even it didn't' crack .. the only place that cracked was where i left a paint stick on top of a board .. so maybe this kind i have is somewhat forgiving .. though thick as mayonaise .. wheel see .. rrr

will update

 

ahoy ..

so .. i laid out the gelcoat today ..

i did it the wrong way .. so we'll see how it works out ..

here's what i did ..

first laid down about 25 coats of super light pva .. it's well encapuslated in hopes of preventing a reaction with the underlying plug .. also i figured out how to spray the stuff good now so there isn't a bit of orange peel or sag .. pva was perfect ..

so i went and did up the gel .. here's what i did .. i understand your not supposed to brush it on .. but i did .. wheel see how it turned out in a few days .. though if it gators up i'm prepared to repair the mould or sand the parts that come out .. i'm an autobody guy so fixing small things in a finish isn't a big deal .. of course i would like it to come out perfect the first shot .. but we'll see .. i don't know really still learning as i go ..

so rrr .. i pva'd that bad boy .. n' got out some brushes .. i picked out the 3 best ones i could find from me box o' 36 and set to cutting even the bristles ..

also readied my little throwaway foam roller tray and rollers ..

first .. i painted with the brushes .. making sure to go back and forthe over the surface to release the air encapsulated on the surface ..

second .. i got out the roller .. the second coat was rolled on to even it some though there was still a good bit of unevenness .. but it was better then b fore ..

3rd .. i got out an old spreader and mixed up some to hit the deeper brush marks and any open pores showing .. and evened it out some ..

i did it all at once .. hitting each step just as soon as the previous layer was firm enough to go on with more ..

the stuff reminds me of an awful smelling finish glaze .. the styrene it puts off is shore nasty even with a respirator .. body suit and glasses on it was uncomfortable to work with .. i did it in the paint booth so that i could keep dust off it this tyme and not worry about getting rained on ..

so far it looks good .. from what i understand .. the gatoring happens when the next vail coat of resin reactivates the thinner low brushed marked spots of gelcoat .. so here 's me plan ..

i don't know if this is rite .. but i'm still learning like i said .. from what i previousely known from body work .. is that filler is also just poly resin with diffrent additives and talc to add body and firmness .. indeed .. on a few occasions i have revived completly dried up dead 'bondo' by scraping the inside of a can for the hard leftovers and adding fresh fiberglass resin .. stirring vigerously .. adding hardner as normal .. and bam .. it's bondo again .. though it does remain a bit tack longer then normal .. it still works ..

you can also thin bondo with resin to make finish glaze .. but i use real finish glaze because sandpaper is expensive ..

but ./. anyway .. so because this stuff reminds me of my glaze puddy .. for the next phase tomorow .. i'm thinking this is the plan ..

to keep the next vail layer of resin from burning through my thin spots .. i will instead brush a thin wipe of straight resin .. then go over that immediatly with finish glaze mixed with resin and a touch of z-grip for firmness ..

my thinking is that this will prevent a real hot layer from getting on my less then perfect gelcoat .. and provide an additional layer should i accidently sand through my tool coat in time with alot of use .. instead of hitting glass and resin i would hit glaze .. which is not very porus also .. and has many of the same ingredients it seems and properties of the gel ..

though all fillers .. glaze included .. contains . talc .. whych is hydroscopic .. (why i use 2k sealer primer over filler .. because it will soak water and rust metal underneath and crack out bondo)

so because pva is waterbased and i may use water to aid in release i don't want to hit the tool gel with even glaze directly .. that's why i'm thinking a thin hot layer of resin .. immediatly hit with a thin leveling coat of glaze with a bit of 'filler' thickner .. this should somewhat protect the first layer from too much eneven heat .. i think .. this is all theory ... learning as i gooo .. like i said .. rrr

.... so anyway that's wats goin' on today .. gonna resin it to fill any porosity and prevent water intrusion then glaze it quickly even .. then hit my vail coat .. and bulk up ..

comments ?>>

it hopefully works rrr.

will update ..