SMC crack advise wanted
05-04-2017, 02:31 PM
#1
SMC crack advise wanted
not a Corvette part but maybe can advise on Olds guy with an SMC problem.
Attached is a photo of my cracked front end stripped to bare SMC.
Can someone advise the best technigue to fix this?
Also the brand names of products used for this.
Thanks
Fred
Attached is a photo of my cracked front end stripped to bare SMC.
Can someone advise the best technigue to fix this?
Also the brand names of products used for this.
Thanks
Fred
05-04-2017, 06:34 PM
#2
Race Director
It would be helpful if you can post more photos ...including the backside of this panel due to it is not a Corvette part.... so I am totally oblivious to what it looks like...where it is mounted on the car.
Cracks In SMC usually crack laterally and not just straight through like the old press molded polyester fiberglass. So making sure it is prepped correctly and ground down to GOOD solid SMC is a must.
Other than that..I would laminate it up with the WEST SYSTEMS epoxy resin (part number 105) and the hardener (part number 206)
Obviously I am only going off what I can see in the one photo..so my comments may change due not being able to see the severity of the cracks and if they completely broke though...other than the holes I see....and if any structural integrity of the part has been lessened due to weakened SMC that I can not see.
DUB
Cracks In SMC usually crack laterally and not just straight through like the old press molded polyester fiberglass. So making sure it is prepped correctly and ground down to GOOD solid SMC is a must.
Other than that..I would laminate it up with the WEST SYSTEMS epoxy resin (part number 105) and the hardener (part number 206)
Obviously I am only going off what I can see in the one photo..so my comments may change due not being able to see the severity of the cracks and if they completely broke though...other than the holes I see....and if any structural integrity of the part has been lessened due to weakened SMC that I can not see.
DUB
05-05-2017, 11:00 AM
#3
Dub
Thanks for the reply.
Here are some additional photos of the part and the backside.
I've never fixed something like this before so ideally I'd like a step by step procedure, something a 6th grader could follow
Fred
Thanks for the reply.
Here are some additional photos of the part and the backside.
I've never fixed something like this before so ideally I'd like a step by step procedure, something a 6th grader could follow
Fred
05-05-2017, 05:39 PM
#4
Race Director
If you want a step by step. Then you need to break this thread up in two separate areas...but still keep this thread the same.
I MUST have very very good photos of the backside of either one of the two areas you need repaired. Your photo above is kinda OK but I am having a hard time actually being able to tell where the damage area is. Either point to it or have a colored piece of paper that will show up in the photo so I can see how the inside of this header panel is made.
As I wrote in the last paragraph of POST#2. If you do not add what you see that does not photograph well and how flimsy or weakened the part it and where fine cracks appear when you twist the part, etc. Then I am wasting my time here....because I do not want any surprises and you come back and say "OH yeah..I forget to mention...."...and then what you just did may need to be cut all back out and do it again.....unless you want to do this repair several times ...just for fun.
The reasons that the photos and how it looks from the backside is SO IMPORTANT is that is where I would perform my laminating...so...the better I can see what you have going on and know what is going on will better aid me in advising you in what to do.
DUB
I MUST have very very good photos of the backside of either one of the two areas you need repaired. Your photo above is kinda OK but I am having a hard time actually being able to tell where the damage area is. Either point to it or have a colored piece of paper that will show up in the photo so I can see how the inside of this header panel is made.
As I wrote in the last paragraph of POST#2. If you do not add what you see that does not photograph well and how flimsy or weakened the part it and where fine cracks appear when you twist the part, etc. Then I am wasting my time here....because I do not want any surprises and you come back and say "OH yeah..I forget to mention...."...and then what you just did may need to be cut all back out and do it again.....unless you want to do this repair several times ...just for fun.
The reasons that the photos and how it looks from the backside is SO IMPORTANT is that is where I would perform my laminating...so...the better I can see what you have going on and know what is going on will better aid me in advising you in what to do.
DUB
05-07-2017, 05:49 PM
#5
OK I labled each crack with a number "F" for Front" "B" for back of same number
Probably still difficult to figure out from photos.
Photos 2 to 5 are near where the header meets the corner openings for the grills. Photo 1 is all the way through but not a corner.
Seems the structure is not strong enough to keep it from cracking? or the stucture is causing it to flex and stress crack?????
Let me know if you need further info.
Fred
Probably still difficult to figure out from photos.
Photos 2 to 5 are near where the header meets the corner openings for the grills. Photo 1 is all the way through but not a corner.
Seems the structure is not strong enough to keep it from cracking? or the stucture is causing it to flex and stress crack?????
Let me know if you need further info.
Fred
Last edited by FStanley; 05-07-2017 at 05:52 PM.
05-08-2017, 05:22 PM
#6
Race Director
OK.
Attempting to do a majority of this from the back. I would use some WEST SYSTEMS epoxy resin and hardener and fiberglass mat. Resin part # is 105.....the hardener part# is 206.
You generally can find this at any major boating place like WEST MARINE.
Making sure it is really cleaned and prepped well on the back side...and you can apply masking tape over any of your open cracks to keep the resin form running out on the front side.
Keep in mind that SMC like to split laterally and generally not straight through the panel...so you might see that when you are prepping it...the area actually gets much larger than what it seemed to be. It can go as much as 3/4" on each side of the crack.
Also....common sense would tell you that if you are pepping an area and it is getting weak and wanting to fall part....STOP.... and do some laminating and then go back the next day and prep more of it.
In your areas where you have pockets. You might find that you might need to cut your fiberglass mat into small pieces and get the strands from if and use them to fill in a hard to get pocket area. It may take a bit longer...but at least you will not be having an air pocket. ADn then....if needed...whenteh pocket is filed in oyumight find that you now can applya alyer of mat over it.
Also...do not think that the resin is good by itself or with minimal fiberglass mat. Really thick application of the resin with minimal may cause for problems. The idea is to get as much fiberglass mat as you can in where you need....about 3 layers of ounce and a half of mat and then ONLY have enough resin to keep it wet. So pouring your resin on it and having is sopping wet is NOT good...but do it if you want to.
we will deal with the front side repairs when you are done with the backside repairs.
DUB
Attempting to do a majority of this from the back. I would use some WEST SYSTEMS epoxy resin and hardener and fiberglass mat. Resin part # is 105.....the hardener part# is 206.
You generally can find this at any major boating place like WEST MARINE.
Making sure it is really cleaned and prepped well on the back side...and you can apply masking tape over any of your open cracks to keep the resin form running out on the front side.
Keep in mind that SMC like to split laterally and generally not straight through the panel...so you might see that when you are prepping it...the area actually gets much larger than what it seemed to be. It can go as much as 3/4" on each side of the crack.
Also....common sense would tell you that if you are pepping an area and it is getting weak and wanting to fall part....STOP.... and do some laminating and then go back the next day and prep more of it.
In your areas where you have pockets. You might find that you might need to cut your fiberglass mat into small pieces and get the strands from if and use them to fill in a hard to get pocket area. It may take a bit longer...but at least you will not be having an air pocket. ADn then....if needed...whenteh pocket is filed in oyumight find that you now can applya alyer of mat over it.
Also...do not think that the resin is good by itself or with minimal fiberglass mat. Really thick application of the resin with minimal may cause for problems. The idea is to get as much fiberglass mat as you can in where you need....about 3 layers of ounce and a half of mat and then ONLY have enough resin to keep it wet. So pouring your resin on it and having is sopping wet is NOT good...but do it if you want to.
we will deal with the front side repairs when you are done with the backside repairs.
DUB
05-09-2017, 01:16 PM
#7
OK.
Attempting to do a majority of this from the back. I would use some WEST SYSTEMS epoxy resin and hardener and fiberglass mat. Resin part # is 105.....the hardener part# is 206.
You generally can find this at any major boating place like WEST MARINE.
Making sure it is really cleaned and prepped well on the back side...and you can apply masking tape over any of your open cracks to keep the resin form running out on the front side.
Keep in mind that SMC like to split laterally and generally not straight through the panel...so you might see that when you are prepping it...the area actually gets much larger than what it seemed to be. It can go as much as 3/4" on each side of the crack.
Also....common sense would tell you that if you are pepping an area and it is getting weak and wanting to fall part....STOP.... and do some laminating and then go back the next day and prep more of it.
In your areas where you have pockets. You might find that you might need to cut your fiberglass mat into small pieces and get the strands from if and use them to fill in a hard to get pocket area. It may take a bit longer...but at least you will not be having an air pocket. ADn then....if needed...whenteh pocket is filed in oyumight find that you now can applya alyer of mat over it.
Also...do not think that the resin is good by itself or with minimal fiberglass mat. Really thick application of the resin with minimal may cause for problems. The idea is to get as much fiberglass mat as you can in where you need....about 3 layers of ounce and a half of mat and then ONLY have enough resin to keep it wet. So pouring your resin on it and having is sopping wet is NOT good...but do it if you want to.
we will deal with the front side repairs when you are done with the backside repairs.
DUB
Attempting to do a majority of this from the back. I would use some WEST SYSTEMS epoxy resin and hardener and fiberglass mat. Resin part # is 105.....the hardener part# is 206.
You generally can find this at any major boating place like WEST MARINE.
Making sure it is really cleaned and prepped well on the back side...and you can apply masking tape over any of your open cracks to keep the resin form running out on the front side.
Keep in mind that SMC like to split laterally and generally not straight through the panel...so you might see that when you are prepping it...the area actually gets much larger than what it seemed to be. It can go as much as 3/4" on each side of the crack.
Also....common sense would tell you that if you are pepping an area and it is getting weak and wanting to fall part....STOP.... and do some laminating and then go back the next day and prep more of it.
In your areas where you have pockets. You might find that you might need to cut your fiberglass mat into small pieces and get the strands from if and use them to fill in a hard to get pocket area. It may take a bit longer...but at least you will not be having an air pocket. ADn then....if needed...whenteh pocket is filed in oyumight find that you now can applya alyer of mat over it.
Also...do not think that the resin is good by itself or with minimal fiberglass mat. Really thick application of the resin with minimal may cause for problems. The idea is to get as much fiberglass mat as you can in where you need....about 3 layers of ounce and a half of mat and then ONLY have enough resin to keep it wet. So pouring your resin on it and having is sopping wet is NOT good...but do it if you want to.
we will deal with the front side repairs when you are done with the backside repairs.
DUB
Fred
05-09-2017, 06:46 PM
#8
Race Director
Apply up to three layer as in one lamination session. this is also depending on you being careful to not allow the area to get super wet and pooling with the resin.
Mix small batches of the resin due to if you try to put a lot in your container and you 'dilly-dally' while laminating...the resin will cure really fast due to the internal heat it builds up within itself....but yet....what you are applying will still be wet.
IF you find that you have areas that are really hard for the fiberglass mat to take shape to due to the 'starchiness' of the mat. You can 'filet' it by pinching it with your thumb and index fingers and separating the mat. That way...it will lay down easier...and thus...means that IF you filet your mat...you can apply 6 layers due to they are so thin and you are not using that much resin to get them saturated.
DUB
Mix small batches of the resin due to if you try to put a lot in your container and you 'dilly-dally' while laminating...the resin will cure really fast due to the internal heat it builds up within itself....but yet....what you are applying will still be wet.
IF you find that you have areas that are really hard for the fiberglass mat to take shape to due to the 'starchiness' of the mat. You can 'filet' it by pinching it with your thumb and index fingers and separating the mat. That way...it will lay down easier...and thus...means that IF you filet your mat...you can apply 6 layers due to they are so thin and you are not using that much resin to get them saturated.
DUB
The following users liked this post:
FStanley (05-11-2017)
05-19-2017, 02:30 PM
#9
Ok here are some photos of the backside repairs as well was what it looks like now from the outside. Yeah I know pretty messy but 1st time I've done this..
I 1st cleaned the part with soap and hot water, then Wax and Grease remover, let it dry for a month in the sun.
Then, ground out all questionable SMC and roughed up the areas were fiberglass mat will layout on.
Blew clean with 150 psi clean compressed air.
Cut 1.5 oz. fiberglass mat to fit as good as possible, and cut out 3 mat layers for each repair area.
Used a small paint brush with cut off brisles to brush on epoxy resin.
Found laying out the each mat layer smoothed out best by dribbling the mixed resin onto the mat from a small plastic cup and then moving the resin around and pressing down each mat layer by hand using nitrile gloves.
Very impressed with the holding capability of the West System epoxy resin.
OK What are my next steps for fixing the remaining repair and finishing the outside? Would like techniques and specific products that have worked long term for SMC repairs.
Thanks
Fred
I 1st cleaned the part with soap and hot water, then Wax and Grease remover, let it dry for a month in the sun.
Then, ground out all questionable SMC and roughed up the areas were fiberglass mat will layout on.
Blew clean with 150 psi clean compressed air.
Cut 1.5 oz. fiberglass mat to fit as good as possible, and cut out 3 mat layers for each repair area.
Used a small paint brush with cut off brisles to brush on epoxy resin.
Found laying out the each mat layer smoothed out best by dribbling the mixed resin onto the mat from a small plastic cup and then moving the resin around and pressing down each mat layer by hand using nitrile gloves.
Very impressed with the holding capability of the West System epoxy resin.
OK What are my next steps for fixing the remaining repair and finishing the outside? Would like techniques and specific products that have worked long term for SMC repairs.
Thanks
Fred
Last edited by FStanley; 05-20-2017 at 08:08 PM.
05-19-2017, 05:22 PM
#10
Race Director
IF you did a vast majority of the repairs on the backside...and they are STOUT...and you know they they are STOUT...then on your exterior areas...you can lightly sand down the repair areas and fill them with Vette Panel Adhesive made by Evercoat.
BUT I am not theee to see what the exterior areas will look like when you prep them for the VPA so I can not 100% guarantee that you might need to grind down the exterior a little bit and THEN add more West System mat and resin....and then when that cures...grind that back a little bit and cover that area withe skim coat of VPA.
UNLESS very careful attention was given to when the first layer of mat was applied on the backside...and how it was prepped...there is a chance that an air pocket can be there and may show up when you prep the outside.
DO NOT wash it or use wax and grease remover when doing the outside. If anything is applied to the raw SMC to clean it ...would be acetone. I am a firm believer to not get the fiberglass/SMC wet with water and using any solvent that can leave a residue behind. But...use what you want.
DUB
BUT I am not theee to see what the exterior areas will look like when you prep them for the VPA so I can not 100% guarantee that you might need to grind down the exterior a little bit and THEN add more West System mat and resin....and then when that cures...grind that back a little bit and cover that area withe skim coat of VPA.
UNLESS very careful attention was given to when the first layer of mat was applied on the backside...and how it was prepped...there is a chance that an air pocket can be there and may show up when you prep the outside.
DO NOT wash it or use wax and grease remover when doing the outside. If anything is applied to the raw SMC to clean it ...would be acetone. I am a firm believer to not get the fiberglass/SMC wet with water and using any solvent that can leave a residue behind. But...use what you want.
DUB
Last edited by DUB; 05-19-2017 at 05:24 PM.
The following users liked this post:
FStanley (05-31-2017)
05-31-2017, 12:24 AM
#11
OK did the Evercoat Vette Panel on the front. works great, wow the best of everything , adheres well, decent working time, sets up great and easy to sand and blends into original SMC well. See photos...
Next step advice
do I just final filler finish with Vette Panel?, do I need to do a glaze to finish the filler work before primer?????
Speaking of primer...
I have some SPI epoxy primer and Evercoat Slick sand and some PPG Urethane primer.
Looking for a great finish. effort no object..
what should I do for final prep for the topcoat? which will be a PPG Urethane top coat.
Next step advice
do I just final filler finish with Vette Panel?, do I need to do a glaze to finish the filler work before primer?????
Speaking of primer...
I have some SPI epoxy primer and Evercoat Slick sand and some PPG Urethane primer.
Looking for a great finish. effort no object..
what should I do for final prep for the topcoat? which will be a PPG Urethane top coat.
05-31-2017, 05:27 PM
#12
Race Director
I do ALL of my body work in the VPA..so I do not use any of the fancy glazing putties due to they would get hard in the can before I used all of it up.
I do not use SPI products so i do not know their capabilities as well as 'porchdog' here on the forum knows.
I am aware of the Slicksand and I would use it but I would apply PPG epoxy primer first and that is only because I know about it and i can get it locally instead of like the SPI products that I would have to get shipped in.
Contact 'porchdog'...and I am sure you can use the SPI primer...but ask him to just make sure.
DUB
I do not use SPI products so i do not know their capabilities as well as 'porchdog' here on the forum knows.
I am aware of the Slicksand and I would use it but I would apply PPG epoxy primer first and that is only because I know about it and i can get it locally instead of like the SPI products that I would have to get shipped in.
Contact 'porchdog'...and I am sure you can use the SPI primer...but ask him to just make sure.
DUB
