Glass fibre & gel repair process.

[J44EAG]

Not much if any glassfibre on our cars, but here for your interest, a repair which I an currently undertaking.

Images show the damage sustained to a yacht in Portsmouth Harbour during the storms in February 2014. This vessel broke a mooring line which caused it to smash itself against the harbour wall. No worries though because I can fix this type of thing in a jiffy or two.

The first action was to degrease the damaged area with acetone which also had a secondary effect of removing transferred scrapes of antifouling paint from the white gel coat. Following that, I cleaned and polished the area around the damage removing salt, grot and a few microns of discoloured top surface gel coat. This brought yellowed gelcoat back to a shiny bright surface finish. Can`t stick anything to muck and what one is aiming for is an existing gel that is bright white which will aid the blending of new material into old.

Believe it or not, this damage looks far nastier than these images would leave you to believe. Whilst looking ragged and unsightly, no structural damage has been sustained. It just looks a right old mess with a few inches of gel and laminate ripped from the hull molding.

The next stage was to clean out minor scapes and stress cracks in the gel with a Dremel type hand held tool fitted with a 1/8 drill bit. One feels like a dentist grubbing out distressed material and chasing cracks down to the base laminate ready for repacking with two part polyester gel filler paste.

That done, I removed delaminated material with an angle grinder fitted with a P36 sanding disc. Great care is required sanding way material. Loose concentration or becoming distracted can cause an unnecessary amount of material to be removed or grinder "smiles" to accidentally be caused to surrounding areas!. The secret is to remove the minimum of material whist ensuring all delamination has been removed and that what you are left with is good solid glass work. One has to realise that the more material that is removed, the more work there is to put it back again!. Outside edges of the damage are sanded back at an angle which makes blending of new material into old far less noticeable but also stops future cracking from occurring at a later date.

This next image shows the damage after working with the grinder and sanding disc. Note the blending out of the damage back to solid material.

Having reached that point, the whole repair area is dusted down with a soft paint brush to remove debris which if left on the ground out areas would make it difficult to create a good adhesion base for new fibreglass material. Scrupulous attention to avoidance of contamination is essential.

That is as far as I got today. The heavens opened so I went off and wired up a radar on another boat! If at first your don`t succeed, give up and go and do something else!

Hopefully the weather will have cleared tomorrow and I can start rebuilding the glass work prior to gelling up the repair.

Total time taken to date on this repair? Less than an hour. I spent more time getting the tools and materials together.

More pics in due course.

Mike

[J44EAG]

Back on the job today with a nice warm climate to help cure new repair material.

The first thing I did was to check over my cleaning out work carried out yesterday. Final blending of edges into the substrate before mixing up polyester resin and fibre mix used to level up areas where I had ground out damaged material or abrasion damage had occured.

Once again the area was dusted off and a leveling mix of polyester and fibre applied in low areas.

Given a couple of hours to set up and harden, I leveled areas with the sanding grinder to just below gel coat level with the angle grinder and sanding disc.

Once leveled I applied a couple of layers of white gel coat filler as a starting base. This is just the start of the filling and flatting of the gel coat process prior to scratch removal and final polishing.

I envisage 5 to 6 applications of gel will be required to achieve a decent profile to the job and to also fill defects which inevitably occur. The techniques employed are very similar to filling dents in car panels. The gel coat I use is a white premixed paste to which a small amount of hardener is added. The product comes in large tooth paste type tubes, is manufactured by Locktite and is better recognized as part of the Plastic Padding range of job specific materials. Cost, around £12 a tube. One tube is all that is required to do this job.

Time taken today. About two hours.

Tomorrow will see me using an electric dual action sander to achieve a roughed out repair, after which more gelcoat paste will be applied until I am happy with the result. Then micro scratches are flatted out and machine polishing brings up the final mirror finish.

Mike

[Brakebuster]

lookin good Mike

i had to do a similar repair to the body kit for the XJS , tricky stuff to work with , but the correct aproach and patience will turn in a good result, and shows this info is usefull for car repairs to

BB

[J44EAG]

Indeed, Vince.

My fake Arden radiator surround was produced using epoxy filler to blend the badge into a surplus grill using similar techniques as described above.

SDC18703 - Copy - Copy.JPG (86.31KiB)Viewed 4979 times

Rained off on Friday which was most frustrating. Not to worry because this gave the gel coat I had applied on Thursday an extra 24hrs to harden up and become easier to sand rather than remaining slightly sticky.

So back on the case again today with sanding grinder and dual action sander with P180 abrasive disc on the drive pad. Cristalic gel coat is the devil to work. Whilst being by its very nature rather hydroscopic, it is also very hard stuff to machine. It is amazing how quickly even course grades of wet and dry production paper become worn when wet sanding gel. This is one of the reasons I try hard not to remove any more material than I have to when cleaning out damage because I then have to replace material and machine it to profile. You know all about it if you have been sanding gel for a couple of hours!

The rear most face of the repair was not too difficult to rough out. The vertical hull side running down to the waterline was a different matter. my sander weighs 1.8kg and working it from a vertical to inverted near horizonal plane is not easy. Firstly the weight of the unit is tiring especially when one has the thing upside down and all the sanding fall out is dropping in your eyes. Every move you make with the sander has an effect. Stay too long in one place and too much gel can be sanded away. Then you have to put some more back in again!

Having roughed the first gel session material to as near a good shape as possible, a round over profile between vertical and horizontal surfaces has to be hand crafted to a matching profile of the other side of the boat. Quite time consuming. Once achieved the sanding dust is removed with a soft paint brush and an acetone soaked cloth used to remove smaller particles. I attempted some photography of the job at this stage but taking pictures of white fibreglass in bright sunlight proved less than satisfactory.

After that clean up, I mixed more gel coat to fill low spots,void and minor imperfections. Not an easy material to apply working off two stacked pontoon floats some three metres off the ground. My duff leg means i have to be extremely careful with footing whilst obtaining the best physical angles to apply the runny gel filler material. It certainly is not that easy to get a smooth application under those working conditions especially as the repair still had voids of differing depths to try to fill with less than a co-operative material.

Here is a view of the second stage fill session taken this evening when lighting was more suitable. Ignore the roughness of application. that all gets sanded down again. A further three fill and sand sessions will be needed before the gel is ready for final P1200/P1500 wet sanding prior to polishing.

Another sand and fill session again of Monday with a view to having the job finished by Wednesday, weather dependent. No power available in the yard on Sunday which suits me fine so I`m off to Lyndhurst for lunch with Portsmouth Region and that has got to be better than gel coat bashing.....I`m being collected as well so look forward to a couple or more good pints.

Mike

[Martec]

Nice to see your 'back' in harness again Mike

Brian

[SteveKK]

Mike,

You not the only one who has been messing around with fibre glass. I've been working with the Quantum Owners Club to restore the original Quantum Sports Car demonstrator. This car required a new nose as the current one had sustained accident damage and delaminated.

The club own another car that we used as a buck to take a mould from. This buck had lots of pin holes and larger bubbles between the gel coat and resin layers which we repaired before making a sectional mould.



Once the mould had cured we had to separate it from the car. Initially screwdrivers were used before hardwodd wedges were hammered in.



Proving the strength of fibre glass the final section was reluctant to release, even though it was being pulled upwards by an engine crane.



This section was being lifted by 2 small wooden batons that had been added to the mould purely to stop flexing, as this is a single use mould. The were only glassed in using 2 rough layers of 300g matting. They were never intended to lift any weight, but were easily supporting over 300kg, being the car, me (100kg!) and 2 other people jumping up and down. It did eventually pop off.



The red car on the left is the one requiring the new nose and the light grey car was our buck.



This is the section of the old nose that we cut off, as it needed replacing due to delamination.



Here is the new nose that was made from our mould. From the initial offering up it looked to be a good fix.



Small plastic blocks were used to screw the 2 parts in place, while they were fully glassed back in place.



We are not flatting back all the joins to prepare the car for spraying.

Regards,
Steve

[J44EAG]

Wonderful work, Steve and thanks for showing us, I bet your neighbours love you!

Release from a mold can indeed be difficult despite copious applications of release agent.

I worked for a few brief weeks for a company as a research engineer developing molds and tooling for wind turbine blades. These were constructed as two half molds with a main spar running down the length of the blade which could be up to 50m in length. The complete half blade as i recall weighed in at around two and a half tons.

Although, thankfully, not involved with the production of those glassfibre, ply, balsa and Kevlar composite units, it was a regular occurrence to hear a blade half was stuck in the mold. Similar techniques to the ones you describe were employed and much hard physical graft could be employed before the blade half finally let go. It was not uncommon for the epoxy gel to part company with the finished product and the blade once joined to its partner shell with internal structure within, would be transferred to a finishing shop for gel repairs to be carried out. Not an easy task. regular mold repair was also a common requirement as sometimes a chunk of mold surface would come out with a half blade. More tears before bedtime.

Somewhere within my emporium I have some pics of a repair I carried out to a fibreglass boat which T-boned a pontoon and sustained damage which once cleaned out was large enough in area to be able to crawl through. I`ll try to find those images and post here for interest. I rebuilt the damaged bow of that boat by laminating an old glass fibre section into the bow stem, then drum skinning two sheets of cloth to the hull either side of the bow to create a membrane on which I could then laminate a new structure. All done and dusted in a week using nearly five gallons of polyester resin and buttering up the final skin with three kilos of bulked out gel coat! Pleased to say even I couldn`t see the repair at the end of the job. Got me loads of work, that job did. Quite suprised myself with the result. Things we get involved with.

Mike

[oldtimer]

Hi Mike,
I'm amazed at what people get up to - and surprised at the excellent quality achieved.

Just imagine what could be achieved if all those "go getters" could be dragged together under one roof

Oh Well dream on

Oldtimer

PS I'll know where to come if I need a caravan repair !!

[J44EAG]

If we all got together, there would be a massive punch up. Too much skill in one place is bound to end in tears!

I`ll repair anything in glass fibre as long as its white. Colours are a no no. I hate colour matching with a passion. It rarely comes out the same as the job you are working on. I turn coloured repairs away. Too much grief.

Glad you are back on the circuit, Phil.

Mike

[SteveKK]

Mike,
You're right, there was a 'little' bit of dust involved. I vacuumed the drive way a couple of times!

Thankfully I have great neighbours, including one who will wander down to check on progress.

Regards,
Steve

[J44EAG]

After around twenty five hours work and nine gel building and flating sessions, The job is jobbed.

The shape finally achieved, the gel was wet flatted with P800,1000,1200 and the 1500 production paper. The scratches and minor blemishes then down to a flat surface, the new gel and surrounding areas were machine polished with a 3m Fast Cut Plus rubbing compound. Washed down with clean water and then acetone to remove all compound traces, the repair is as good as it gets.

So from this...

To this....

Mike

[poprivet]

Its always enjoyable to see what others get up to. Great work Mike and far more involved then what many would expect.