Bleach clean interior GRP gel coat - need to thicken it up

superheat6k

superheat6k

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Whilst my engine is removed I want to get rid of some staining in the gel coat in the area beneath the engine, so two questions for the chemists ...

1 Any reason not to use neat household bleach on GRP gel coat ? I intend to leave it on the surface for at least a day possibly two.

2 Is there something I can add to the bleach to thicken it up so it doesn't run off the surface whilst doing its job, but that I can easily rinse off when I'm done e.g. edible flour, wall paper paste, etc ?

Thanks
 
I've used bleach on grp with no noticeable side-effect, although I recently used oxalic acid and it worked way better on exterior hull staining. Might be worth a try anyway.

Thickening oxalic with wallpaper paste seems to be the norm, no idea what bleach might do to it though.
 
Let us know if bleach works as I have tried oxalic acid which didnt make much difference.You can buy thick bleach in supermarket.
 
pvb said:
Don't think there's any reason not to use bleach. One of the best bleach-based products I've found is HG Mould Spray - it's bleach and sodium hydroxide (caustic soda) in a spray bottle, Very effective stuff. Sold in B&Q and lots of other places.

HG Mould remover, 0.5L | DIY at B&Q
Click to expand...
Thanks. Annoyingly I was in B&Q about 2 hours ago. However I have some caustic soda.
Does mixing bleach with CS cause a chlorine release ?
 
Watch out for the fumes!! Bleach in a confined area can be very overpowering and cause eye stinging and runny nose if inhaled. Prolonged exposure could get into your lungs so wouldn't be beneficial to you (unless your name is Mr D Trump, in which case, inhale away it, will stop CV19 apparently!)
Use a decent mask if staying in the area and gloves/eveshields.
 
superheat6k said:
Thanks. Annoyingly I was in B&Q about 2 hours ago. However I have some caustic soda.
Does mixing bleach with CS cause a chlorine release ?
Click to expand...

No but bleach is already pretty strongly alkaline.

It's mixing bleach with acids or any acidic cleaning compound which is dangerous ... Do not be tempted to mix bleach with oxalic acid or any descaling chemical.
 
I use straight bleach on the flow coat inside my boat. Gets rid of mould nicely. I would never use a spray applicator just too much aerosoles in the air for your own comfort. Put bleach on a rag and apply to surface. I don't think it needs to stay on for long. Perhaps soak a rag and hold it to the area for longer soaking.
Caustic soda is vicious stuff and very dangerous. It does sometimes soften paint and grease. Won't touch antifouling paint but rips the paint off my trailer quick time. I certainly would not mix it with anything but water. It just gobbles up animal hair brushes. Use gloves.
I would try kerosene then acetone for grease.
Oxalic acid seems better for organic type stains. Try by all means but only after cleaning off other cleaners. ol'will
 
I dont think the op wants to get rid of grease or mould its the yellow staining and wants to whiten the gel coat,I have the same yellowing around the engine and have tried various cleaners without effect.
 
pvb said:
Don't think there's any reason not to use bleach. One of the best bleach-based products I've found is HG Mould Spray - it's bleach and sodium hydroxide (caustic soda) in a spray bottle, Very effective stuff. Sold in B&Q and lots of other places.

HG Mould remover, 0.5L | DIY at B&Q
Click to expand...
It works fine on things like headlining - but DON'T drop it on anything you care about as it will bleach any fabric, wood or whatever. My wife and I both have a collection of clothing with white streaks resulting from small splashes of the stuff.
As others have noted, it releases chlorine, which in a confined space isn't good for you, despite Mr Trump's ideas! So good ventilation is essential. A mask won't stop it, at least, not reliably unless it's a positive pressure system.
 
superheat6k said:
Whilst my engine is removed I want to get rid of some staining in the gel coat in the area beneath the engine, so two questions for the chemists ...

1 Any reason not to use neat household bleach on GRP gel coat ? I intend to leave it on the surface for at least a day possibly two.

2 Is there something I can add to the bleach to thicken it up so it doesn't run off the surface whilst doing its job, but that I can easily rinse off when I'm done e.g. edible flour, wall paper paste, etc ?

Thanks
Click to expand...
would it be easier to deploy some danbolines? Paint over the stains, which may be hard/impossible to remove.

Sure to be quicker...and you'll have enough to do your gas locker at the same time.
 
RJJ said:
would it be easier to deploy some danbolines? Paint over the stains, which may be hard/impossible to remove.

Sure to be quicker...and you'll have enough to do your gas locker at the same time.
Click to expand...
Absolutely no way I am putting paint on the gel coat, but thanks.
 
Mix bleach and washing up liquid... leave to soak and wash/agitate with a brush...

You could try some degreaser on the heavy spots in advance...

I will be doing the same but mine is mainly rust so I'll be using oxcalic acid mixed in washing-up liquid followed by the powerwasher
 
superheat6k said:
Absolutely no way I am putting paint on the gel coat, but thanks.
Click to expand...

I've used bleach or oxalic acid in various places, with varying degrees of success. Bleach is good on deck for getting rid of green growth, not so good on your trousers though. Oxalic acid is great at removing rust stains and cleans foam backed vinyl really well. Neither seem to be at all good with grease or oil, so you'll have to thoroughly degrease the engine bay (suspect you already have). I also suspect that neither will remove the yellow staining you mentioned.

If you really want to restore the colour you might have to resort to wet & dry. If that's not successful, a couple of coats of gel/flowcoat wouldn't be the end of the World.
 
pvb said:
Don't think there's any reason not to use bleach. One of the best bleach-based products I've found is HG Mould Spray - it's bleach and sodium hydroxide (caustic soda) in a spray bottle, Very effective stuff. Sold in B&Q and lots of other places.

HG Mould remover, 0.5L | DIY at B&Q
Click to expand...
Went into B&Q again today, but was surprised by the range of HG products available, but one of those I picked up was the mould spray which I wil be trying tomorrow, along with some very strong parazone bleach with surface cleaner (I will try these separately !).
 
there is also a product that which contains bleach and a mild grit like jiff with bleach or something ( I think jiff is called something else now)... like that in a purple squeezy bottle that is really good on some stains with a green scrubber...
 
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