Glue, Mrs C need help

[chunkolini]

Hi Guys
Mrs C has been getting into making mosaics lately and is having problems with bits falling off.
So far she has used superglue from the hardware store to glue the bits back on.
She is using a base of concrete with a mix of pebbles, ceramic shards and glass and bits of My brazing rods. A complex mix of materials.

See example.
The bits that fall off are typically ta few of the ceramic or glass bits and the metal components.
Can anybody recommend a glue that will deal with this reliably.
Below is another example.

Many thanks from
the Chunkolini's.

 

[brightspark]

araldite rapid or silicone sealant. bonds to concrete glass and metal

 

[blacksmithstris]

Hi Chunko,
My partner who's business is boats- he sells them but is involved with people who make sails and who fix them, everything from big boats and little fibreglass or composite racing ones, has introduced me to an adhesive called "sika flex" It is used to build and fix boats with so you can imagine the stresses that it has to withstand for that. It comes in black, brown and white.
The stuff is amazing, when it dries it is slightly rubbery, in that there is some give to it. I use it to glue bits of metal to wood for trophies. It is incredible how strong it is. It is very thick and sticks to everything that you apply it with so it takes some careful handling and it is a bit pricey, but might be worth a try anyway!

I love the flowery one, i like the lion too, I did some mosaic work with my daughters class and it was good fun, since then made a mirror frame with beach pebbles and we have a big concrete retaining wall in the back of my house and been meaning to do some mosaic bits on that, still collecting the materials!!!

 

[Sean]

Worked making mosaics and running mosaic courses for years I'm in some of Martin Cheeks books

what's the support- the board? MDF is terrible as it moves about too much with changes in moisture and sheds the applied material.

2 part epoxy but not the 5min stuff as you need a longer open time

PVA works surprisingly well on most ceramics as long as the backs arent too textured.

some of the 2 part cement adhesives are good my favourite is Mapei adisilex gauged with latex plus, super sticky! used it to stick stainless disks on to concrete sculpture.

edit OOh concrete - is she casting the concrete over the mosaic or sticking the material to the concrete? for the latter go for a cement based polymer modified tile adhesive a big bag should cost less than £25 - topps and the like will charge upwards of £50 Again dont go for the rapid set as she needs the "open time".

its all about technique - PM me with your mosaic specific questions with particular attention to the correct materials for the correct method.
Sean

 

[gordon stephenson]

After making the cement base would it work to give it a coat of PVA on the surface before pressing in the pattern work?

 

[chunkolini]

As usual quick answers.
She is not using MDF as backing.
The construction is done face down, she lays out the components on a bed of sand then tips the concrete on the back to make a slab.
Some mug was bribed to make a few metal frames to hold them in shape, these are unbolted to release the mosaic thingy.
Glue needs to be invisible when used, sticky and preferably easy to handle.
I can see these being properties that are probably not very compatible with each other. Also ideally fairly quick to cure.
I reckon probably a two part epoxy but they are a pain when you only need tiny amounts.

 

[brightspark]

araldite rapid

http://www.tlc-direct.co.uk/Technical/DataSheets/Laybond/FXARS.pdf

 

[Sean]

After making the cement base would it work to give it a coat of PVA on the surface before pressing in the pattern work?

no PVA goes "live" again when in contact with moisture and will create a weak bond prone to spalling or flaking off

if casting then it needs to be a "monolithic" so that the decorative material becomes incorporated into the matrix -see "Maggie Howarth"

make the design in a bed of sand at the base of the mould then pour in the concrete and leave to cure - trouble is you cant see the finished surface and small stuff like the braizing rod will be overwhelmed

pressing in to the surface of a poured slab is un reliable as the concrete mix can begin to dry before it cures and you get the material falling out as its weakly bonded also when working the material you can get the water coming to the surface again forming a weak bond especially if the material is smooth.

 

[dickie bell]

Reckon silicone sealer would do the job ,they look great btw I really like the lion.

 

[chunkolini]

Sean says
'if casting then it needs to be a "monolithic" so that the decorative material becomes incorporated into the matrix -see "Maggie Howarth"

make the design in a bed of sand at the base of the mould then pour in the concrete and leave to cure - trouble is you cant see the finished surface and small stuff like the braizing rod will be overwhelmed'
That is exactly what is being done.
The problem is when she turns it back over and before the matrix has completely cured some of the small pieces are dropping off.
Main query from Mrs C, if she uses superglue and it seems to hold will it fail long term?

 

[Lawnmowerboy]

I would have thoght polyurethane glue mastic stuff like tiger seal would work well. Seems to like the concrete in the garage and the tiles in the kitchen- Mother wasn't happy!

 

[Sean]

nope anything that has a high viscosity or any sort of body wont work as well because it holds the piece out of the hole from which it fell, you need something that doesnt interfere with the tiny gap Pu sealants like tiger seal or the silicone stuff do stick very well but they will hold the piece proud of the surface.

 

[Lawnmowerboy]

Mosaics are fairly well textured anyway?

Sorry to state the obvious but what about ceramic tile cement?

 

[KemppiFrog]

The recommendation above for Sika Flex would be my +1, I use the 11FC type, comes in white, brown and maybe some other colours. As a PU, it doesn't mind a bit of damp. Sticks like the proverbial to just about anything, and is aimed at ceramics and concrete. Comes in 300ML tubes, if carefully sealed, can be used over time in little dabs. Also thin enough to squeeze behind those loose bits without raising them.
KF

 

[Keith 66]

As a boatbuilder i use a lot of different glues, Sikaflex is good stuff but is expensive & has a high "goo factor" ie it tends to string & get everywhere.
It is a one part polyurethane sealant adhesive and there are plenty of cheaper versions of the same stuff about, PU40, Soudal etc, often half the price of Sikaflex & just as good. In my experience sealing tubes doesnt work very well & you usually end up throwing half the tube away as its gone off.
I think for sticking odd bits back on one of the thickened Cyanoacrylate superglues is probably best plus you can use Zip kicker for an instant cure.

 

[pedrobedro]

PU would do it but once you start a tube you have to use it, there is no way to keep it from setting in the tube. Something like the no-nails look alikes available would do it for a lot less money but you could do them in a bed of fix and grout and they should hold themselves in.

 

[DrNik]

car filler, can be slightly thinned with thinners,mixed with hardner and poured/spead over the back, once it sticks and goes hard its like $**t to a blanket

 

[chunkolini]

We will go with super glues and zap kicker, had forgotten about that stuff.
She is anxious to keep things loking unrepaired re colour etc
Yet again quality advice on a completely non welding subject.

 

[Lawnmowerboy]

Tigerseal is the same thing as sikaflex as far as i can see. But about £3 cheaper.

 

[KemppiFrog]

Sika 11FC is about £5 a tube. How does that compare with the UK? And, being a tight bars--ward, I can seal the tubes to last a few weeks....
KF