Tooling gel coat application

Hi to all, I am building a 33 feet ( 10 meter) boat hull mold and will soon have to face the covering of the plug with tooling gel coat, So far our attempts to apply it by brush have been relatively successful, but we believe that it really really is something very difficult to do, since the first coat must be relatively thick (500 microns) and the material is what we call ( as the opposite of friendly) an hostile material which totally refuses to cooperate we never managed to achieve a relativeley uniform thickness ( despite there being videos in youtube showing how is done and looking easy).

We will buy an airless gelcoating machine ( glascraft ) next week but much to my surprise, despite there existing in the market several renowned brands that offer tooling gelcoat for spray application, it seems that almost nobody uses it, most of the users of tooling gelcoat favouring its application by brush.

For the size of our job and having found brushing to be an almost impossible way due to its inherent difficulties I wonder why is it that ( at least here in europe ) people does not use the tooling gelcoats formulated to be sprayed instead of the extremely difficult and inconsistent method of brushing it.

This is what we are making: ............

 

From the pix, that doesn't look ready for tooling gelcoat. Maybe we use different terms for things? I'm thinking at the point you are, I'd be spraying something like Duratec on there to sand through the grits a final finish.

Ever heard of a dump gun? They are crude & cheap but way better than brushing. They use an disposable paper ice cream cup for holding your gelcoat. Real easy clean up as well.

Link : Dump gun link

-jim lee

 

Yes Jim, we will be applying some Duratec first but when the plug is ready to tooling gelcoat I need to have solved any doubts and taken decisions about what to do with a certain amount of time in advance, thank you for trying to avoid us a costly mistake

 

In regards to the dump gun, we believe that for the size of our hull and other pieces we have no way to escape from buying a proper gelcoat dispense airless spray system, primarily for the application of the boats and pieces gelcoat but having the machine we would like to use the system for the application of the tooling gelcoat as well instead of brushing it over our male plug, bear in mind the large surfaces to be covered .........

 

I never had any success with brushing gelcoat. First coats would be streaky thick/thin, second coats would usually alligator the thin streaks of the first coat. Rolling was more successful. The dump guns are fast, uncomplicated and very cheap. It would be a lot of cup changes and gelcoat/ hardener mixing on that large of a project though. I just looked and see they have an external mix model.

The "proper" system is the way to go for production. One of the limitations of the dump gun was, being gravity fed, it more or less had to be spraying horizontally or down, spraying up doesn't work.

 

Hi Sam, we bought a Glascraft gelcoat dispensing and spraying machine internal mix today, we will recieve it in a couple of weeks, what amazes me is that I know shops that despite having several spray machines they apply the mould tooling gelcoat by brush, and completely agree with you with waht happened to you when applying the stuff by brush ..........

 

Before you start take you cell phone out and away from the work area .

Ah brushing tooling gel !! Now thats something a havent done for a long long time !
You know why people still brush ??
Lets get back to the absolute basics of gel coat and what takes place when you mix the catalyst and gel coat together !!
what happens to it ??
what takes place ????
any one want a guess?? :?:
willcome back at the end of this !!

Ok tooling gel you need everything perfect for the time you apply it , temprature , humidity, the right Catalyst , and the correct ratio !! and very important a wet film thickness gauge !!
Once you ull the trigger and start you dont stop for any reason at all even if a naked girl walks by you dont stop!!! .
If you are using a gel coat gun make sure theres room to move the gun from one side to the other with out any time delays so you keep getting wet on wet spray , always dry run the moving of the gun, the placement of the hoses ,make sure the airlines and all the right length with spare and theres a really good water trap to get 100% dri air to the gun check the accumilater tank at the compressor end and drain any water out all before you start!!, check all the hose conections to the gun !!.
School up your assitant to check the gelcoat drum level as it being used and keep it topped up and the pump never sucks any air ever !!! he also needs constantly check the gun catalyst pump sight glass to make sure it pumps the same amount every stroke .
Lots to remember ah !!
The gun is just a machine and machines break down so be prepaired !!
.Do you have a plan B ??
Do you own a pressure pot you can carry on with if the gun stops and wont go again ?? Remember you dont want to stop for any reason more than a few minutes or you could have major problems !!! .
The pressure pot nneeds a trial run as well so all will work instantly . Got you catalyst measure sorted and containers for the pressure pot plus a stirer sorted . Dont want to have to go looking for anthing at all for any reason .

Ok back to the brushing gel coat story = Gel coat begins to gas the instant the catalyst is poured into a container , The gas forms bubbles and the gel coat is a semi liquid and has a bubble release chemical built in BUT if the gel coat thikness is to great and it starts to gel the gas is trapped , giving you porosity !!
Brushing is a way of squashing the entrapped gas out if the gel coat as you move the brush back and forth across the wet get . The best shineyest old moulds i have ever seen in my life were all hand brushed . its all we ever did years ago . Porosty was never heard of and i never knew what it was till more and more things were sprayed with a gun not only tooling but top coats as well . always second coated when we brushed !!but used a paint roller for the second coat !.
We always brushed the applied gell 6 time back and forth and then another brush full went on ,6 strokes and the more gel and so on and so on till the job was finished . At the end of a big job your arm felt like it didnt belong to you and was going to drop off .

I am sure there will be lots more added stories than just mine !!

 

Just to add to whats already been written about !!
Spraying at a even thickness is not a impossible task , it just take persistance and care ! constantly checking with a wet film thickness gauge as you go . What you have to constantly look at is the finished spray pattern !,what does it look like !! thin is stippled , thick is smoothed out a little , just right is somewhere in between , always carry the thickness gauge with you all the time checking as you go !!,dont have a wide fan !! ,some times the fan will cover up to 2 feet wide in one pass but the thickness is very thin and the thickness across the fan is never consistant from side to side, also dont be tempted to get up to close to the surface as the force of the gel coat coming out of the gun splatters the coat you just sprayed and can cause craters to form !! with a gun it needs to be about 700 mm away from the mould surface with a spray about 500 mm wide !!,each pass you need to overlap about 50%of the last pass with the next spray so in reality you are only covering 250mm wide as you go but its getting two coats !!. adjust the speed of each pass as well !,to quick thin !!! to slow thick !!
Calculate the moulds surface area = how much gel per sqr mtr do you need , then as you are working you can calculate usage to mtrs used to quickly check how much you require and how much you have used . to much means thick !!to little thin !!!. Use your gauge !!
A good gel coater deserves top dollars becasue its a art !! its not just a job !!, anyone can pick up a gun and pull a trigger ! some people never learn and will never pick it up how to spray properly , some are naturals and you are very lucky if you can find one because he is the person you need to cultivate and keep no mater what !! and some are just a pain in the backside and cause more problems than i care to write about .
I could write a 100 pages on what to do and what not to do it a waste of time . learn and find out things for yourself .
I been traveling and teaching glassing and gel coating etc etc in quite a few places and have done it for years . I am in the process of showing and training some chinese guys just that .Was in Korea before and they wernt any better but they were all professional fibreglass laminaters and done there job for ages and were of the opinion they were the best BUT havent go a clue !!
its all up hill every day . its just a job to them , there is no wanting to be better or improve ,next day they are right back where they were the day before and have to show the same things over and over again just never sinks in !!
Do i get pissed off ? never !! because i love the asian women and are streets ahead of the males and they always want to learn !!!

 

Hi Tunnels, thank you very much for your tips, very much appreciated, we will try to do as you say, ( including finding a lovely asian woman who is always willing to learn new techiques )

 

Keep me posted use the private answer if you want i am on holiday at the moment for another few days . then back to a 48 foot deck we left half finished a week ago .
No one will remember what they were doing so like starting all over from scratch again .

You using dura tech for the paint job on the plug ?? I would use a bright coloured hi build undercoat as a first coat so when you are sanding with long boards etc you dont rub through into the wood and have to respray again to many plases again . . !! what do you use to spray with ??
While in Korea i made 2 complete presure pot spray units and thats what we uses to paint with and to gel coat as well . Just a few basic things and a pot system can do almost any job including spraying high gloss 2 pot paints and varnishs etc etc and many other things as well

 

mold and plug building

hello i have made lots of molds over the years and found that for making the plug we used epoxy for this as its a one time use and can be easily sprayed to a good thickens the Les wet sanding you can get away forum is best as this in its self is going make the work somewhat more on the long run and the need for pva mold release spay aside forum the release waxing as a rule only 1 cote of wax shooed be put on a day for a min of 5 cotes on a plug the last thing you need is for it to get stuck on the plug this i have had happen and is not much fun trying to separate them with out damage to the new mold molds don't like to be sanded a small flaw in the mold is going to translate to every part you pull forum it same for the glassing of the plug never use roveings in the first steps the heat of the reasons gelling will draw on the fiber lines and leave a transfer print on the mold this is a bit hard to remove after and keep that nice shine finish you worked so hard for the only time i use a tooling gellcote is for doing fix work on a damaged mold i found spaying a good dark green or black epoxy with a good sprayer is best on the long run now on the plug if you do need to do sanding allows do with good clean water and don't use a hard wood block as a backing i like to use good hard fome you get no hard egad and it holds a bit of water to this is good. if you not all so good using a good sprayer try ti find a car body guy for this part of the job as they have lots experiences with spaying fine paints you can even go as far as doing more then 1 cote with a wet sanding between them just rember just use a degrees-er cleaner before the next cote. what you see on the plug is going show up on the mold and as for support framework of the mold after i never place the frames agenst the mold serfes in a shot time this is going to make draw makes showing the outline of the frames on the outside of it what you do is sup[ort the frames over the mold then lay tabbing of glass forum it to the mold if you intend to make a few boats forum this mold its good to spend the time now and do things right then end up fixing every part after a good mold build for me is to have at lest 5 layers of mat on first 1 layer at a time over a few day time in as long sections as can work with in the gelling time span i allwis use a 1/5 OZ mat for the first layer as that's the most inportint one you need role it out so all you see if the color behind it the glass fibers shooed look like is disaperd in the wet reasons even a we small air bubble can make a problum for you as this will exspand in the tempitor change of the day to night and can crack the molds cellcoteing the other thing you need look at is the humity level of the shop when your doing the first layers of glassing if its to humid this is going to inter fer with the resins curing time because of how its mixed you shop you buy this forum shooed have a data sheet on it and the working temp to be best and doing your mane layup on the mold shooed be for a good one at lest 5 layers of mate let to stand for at lest a good 2 weeks before you start doing structural work then i wood only use 18 oz rovein do like this lay a 3 ox mat then a 18 ox rovein then let sit a day to cure then do this agen 2 times then you have a good stable base that not going give you transfer of things to your boats for atching the support frames this you can go to using 24 oz and stay with the 3 oz mats this going cut down lots time aplying the glass tabs to the frame frum the mold you need do this in as long as pice you can handle working with a good way speeding this up is using a resin resistant fluffy roller the fiberglass shop have this and i personally like the Teflon air rollers in 1/5 and 3/4 inch for the glassing on the big open space you can use the 3 by 10 inch inch aluminum rollers the thicker you make the mold the longer its going to hold the shape hope this gives you some help as i have worked in this for some 30 years building every thing forum 200 mph race boats to 50 foot fishing boats in fiberglass.. now for gelling for the mold this is a bit different its most inportint not be to thin this levees you no working room for fixing things down the road all the best mold i have made and ones i have seen all are done in black for a few different reasons for me the mane thing is seeing what your doing when you go to build a boat and pant the well waxed mold in time the waxing of it starts to get a build up that needs to be cut pallishd off i like using magwiers fine cut for this its fast easy to use and water wash it off after you use it for the re waxing but for now lets just say is a one off i like to treat then all same as is i plan to make 500 out of it the mold release wax is the most inportint thing if you plan on not having it stick other trick is to flote the boat loos of the mold when your done making it this is going do 2 things for you help protect the mold and free the boat with out all the pulling and pounding the mold i try not to use a grinder on the top egd of my molds i dont like cuting in to them i try to time my glassing so i can use a long blade razer knife to cut the eases off but you need be cearful doing this as to not drag the glass most time if ime going have a roveing finishd layer ile lay a 2 inch wide stip of 1 1/5 oz mat along it makes for a better cutting
thears good mold gells for spraying to build a mold with

 

Hi Tunnels, we will be sprayin duratec surfacing primer and as a last coat some more primer but in this case mixed 15% with some duratecs polyester high gloss coating.

We just purchased a Glascraft gel coat dispensing and airless spraying system internal mix, and we would like to do all the resinous coatings of our plug with it, we hope that with a samll enough spray gun tip we will get a nice atomization in order to avoid as much as possible getting a strong orange peel.

We are right now applying some polyester shop made fairing filler putty but when we finish the surafce treatments on the plug, hopefully in around 20 days time, we will be in need to spray with our new spraying machine some tooling gelcoat, we will also use it to dispense de tooling resing to the "lamination crew" as we have not used one of those machines before we are a bit "worried" ............

Thank you for your expertise and help, wish you where closer ..........

 

about Glasser´s tips, I found difficult to understand his message maybe becuase english not being my native language, I still understand he was trying to help with his long tips list, thank you anyway.

 

Ok i understand your concern if you have never used one of those types of guns before . How old ?? new of second hand ?? any spare nozzels with it ?? .
The one i have at work at present is a venus but a older unit with a inline heater unit which we need when it gets cold ! , they are all simular just differant . The width of the fan is in the nozzel you use and usually the pressure to the pump also changes the flow rate so the fan will change a little as well but not a lot !. .
The differance when spraying resin is keep the pump pressure down a little and the nozzle you will need is not the same as the gel coat nozzle possibly the same degrees of spray angle but a slightly bigger hole to pump more resin onto the glass, When you start to spray resin measure the square meters of your glass and work out how much resin you will need and with a set of good scales you can put on the right amount of resin to the amount of glass you have its all good practice for when you start to build your boats . It is so easy to add a bit here and a bit there and another bit some where else and befoe you know it 50 kgs of resin has gone on the job and when it comes to the final weigh in there could be some red faces and questions being asked why is it si heavy ???
When i had my own department building 100% to a survey standard we had scales for the resin ! scales for the catalyst !! and weighed the glass that had been precut . Our QA person would hand me a piece of paper and say thats whats needed to wet out that amount of glass !!. 99 time out of 100 i always managed to come in just a few grams less resin than he has specified . Just takes practice and persistance continually from all the staff all the time !!!.
Can you post some pictures of the gun head assembly and also the main pump and pressure gauges and catayst unit we must be able to sort it for you !. they really are quite simple and pretty basic .
Just as a matter of interest what size is the compressor you have how many cubic feet of air does it pump ? Minimum for a gun would be 28 cubic feet and if possible always use 1/2 inch air hoses or bigger to the gun from the wall fitting , all the way to the gun .
Makes a big differance to the operation of the machine and also stops iceing up becasue the air moves slower along the lines . all the hose i use are 19mm inside with 1/2 couplers but our comressor is a long way away for us

Yes i have written a lot of information here for you !!,read it slowly and if theres things you dont completely understand tell me !!I want to help you and give you as much as i can with the limitations of writing !! i work every day with non english speaking workers but i am a hands on person and i am able to show and use a interpriter lady to get my message across at work !!. So lets take it slowly and ask quetions .
I have over the last 12 months written a complete service manual and operators manual plus compiled and list of trouble shooting problems and a million possible solutions to solve any problem that could possibly arise in a whole life time when working with and using any of the guns we have !! 2 gel coats and 3 resin guns with choppers , each one is slightly differant from the other .
For the real tricky stuff thats just about impossible to put on paper and is completely impossible to transllate into another language specialy Chinese !!, we compiled a serious of short video clips titled and with Chinese voice over .
My translation lady gets a pair of overalls on and a mask and stands with me when i am working . She is a gem !, always before i get to involded with something completely new i always walk her through everything in fine detail so nothing is left out or can be misunderstood !!.
Difficult !!! you should try it sometime with a bunch of deaf people ,because thats what its like .

 

That's too bad as there is a lot of good information there. It is hard to read though.