Epoxy glue, how much to put on ?

[simonfraser]

I have two flat surfaces, porous / wood, so should stick like ...

How much to mix up per sq cm / foot so it does not squidge out all over the place ?

Many tnx.

 

[DownWest]

Depends how level the joint is. What is important is that you get a bit of squeeze out all round so as to confirm the joint is not starved. Unless it is rapid curing (temp?) just mix a guess, then mix a bit more to finish.
I always have a few filleting corners ready to use up the extra scraped off.
DW

 

[Boathook]

Depends how level the joint is. What is important is that you get a bit of squeeze out all round so as to confirm the joint is not starved. Unless it is rapid curing (temp?) just mix a guess, then mix a bit more to finish.

DW

+1 I prefer to mix too much just to ensure the joint is wet. With epoxy though you do normally have time to put in place and remove to see whether contact is made all over.

 

[maxi77]

Some also suggest the use of micro fibres in the mix to prevent glue starvation

 

[oldsaltoz]

Some also suggest the use of micro fibres in the mix to prevent glue starvation

I would say esential,

Make sure the timber is dry, fully coat with epoxy resin (5 coats) and let it cure overnight in a warm ventilated area.

Sant the area to be clued and wipe with Acetone, also wipe the area you plan to glue to after sanding it.

Mix resin and hardener then add Micro-fibres, mix to peanut past consistency and spread over the area to be glued, making sure you have a minimum depth of 3 to 4 mm and slight dome in the centre to avoid air entrapment.

You can add 3 packers (Match sticks or other) to control the depth of resin. Slowly lower the item and use a bit of dowel or other round object to remove the excess resin, this will leave a neat coving around the edge adding strength and making it easier to keep clean or glass over if required.

Hope this helps.

Good luck and fair winds.

 

[William_H]

Resin thickness

Hi salt Oz you seem to suggest using match sticks to ensure a quite thick resin layer. I would have imagined painting both surfaces then clamping them together to get squeeze out all round would give the strongest joint. Is there a reason or technique I am not aware of?
Of course the resin will usually prove stronger than the resin to wood bond on destructive testing of samples but why more resin?
regards olewill

 

[oldsaltoz]

Hi salt Oz you seem to suggest using match sticks to ensure a quite thick resin layer. I would have imagined painting both surfaces then clamping them together to get squeeze out all round would give the strongest joint. Is there a reason or technique I am not aware of?
Of course the resin will usually prove stronger than the resin to wood bond on destructive testing of samples but why more resin?
regards olewill

Hi Will,

Still well above 30c for the month I see.

In testing to destruction I have observed that method is actually stronger than just resin and the it's the timber that fails and not the glued surface. This applies to sheer and pull/separation testing, I suspect the extra layer of fibres provides stiffening within the joint.

Hop this helps and also hope it cools down a bit over your way.

Good luck and fair winds.

 

[DownWest]

Forgot the fibres bit, I use Resoltech resins which have the thickener already in the glue.

 

[oldsaltoz]

Forgot the fibres bit, I use Resoltech resins which have the thickener already in the glue.

There is a huge difference between filler and Micro-Fibre. I am not familiar with the product you are using, can you tell me what the thickener is, is it a chemical additive or some other material?

 

[DownWest]

Hi OSOZ,
http://www.resoltech.com/IMG/pdf/DS-2040G.pdf is the info. But does not indicate which. IIRR from chatting to the sales director, it is a fibrous filler, the resin is an opaque white. I did a series of tests of the type of joints in my boats. Mostly lap, scarf and T, and the results were very good. Precoating with the 1010 resin does improve the result, but only by a bit. It was always wood failure.
DW

 

[srp]

To give a more specific answer to the op regarding quantities, I glued up a tiller blank yesterday from 5 laminates ( so 4 glue lines). Each laminate was 75 x 900 mm, so the total area was 0.27 sq m. I used 85g of mixed resin, so 70 g resin and 14 g hardener (SP106). I also added microfibres, probably around 1.5 dessert spoons. As others have pointed out, you really have to plan for some squeeze-out to be absolutely sure that the joint is not starved.
Unless I am deliberately filling gaps or building up a fillet, I aim for a thin glue line. While epoxy is fine with gap filling, there is no necessity to have a thick glue line.